The New England Journal’s Disappointing Decision to Publish the Boston School Mask Study


This week, the New England Journal of Medicine published an observational study claiming that lifting mask mandates in schools in Massachusetts was associated with increased COVID-19 rates.

First, even if these results were true, they have no applicability in the present. Seroprevalence has rocketed past 90%. Most kids have already had COVID. Ergo, they no longer need protection from COVID (which they will get again, eventually). Whether mask mandates avert RSV or other viruses is speculation, and contradicted by a mountain of pre-pandemic data.

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Second, these results aren’t true— they are unreliable, as detailed in this post by Tracy Beth Hoeg. She is going to walk you through the technical issues, including the crux of the matter: difference in difference analysis cannot handle time-varying confounders, and time-varying confounders are guaranteed when mask mandates fall. 

Third, observational data will never settle mask debates. In recent years, a number of groups have asked what happens if the same dataset is approached with different analytic plans. What happens if you give the same data to multiple research teams, or if you simulate many analytic plans. These studies show observational studies can give a range of results, in many cases, they can conclude an intervention is harmful or helpful depending on the plan.

Masking kids is a divisive issue. Our friends across the pond do not do it. They do not like doing it to kids under 12. And they will never do it to kids under five. Our country is full of pro-mask zealots. They love masking kids. In this case, some of the authors of the NEJM paper have repeatedly advocated for the policy of masking kids in school. 

What am I to think? When you give someone a question that has tons of analytic flexibility, and they have already said they vehemently support the policy. Their analysis delivers what they promised.

Is this science? 

Fourth, the discussion of the NEJM paper says, “structural racism is embedded in public policies and that policy decisions have the potential to rectify or reproduce health inequities”. They authors frame masks as a tool to lower structural racism.

Whether masking kids slows respiratory viruses is a scientific question, and it is a dangerous to turn this into a proxy for political debates. I believe it is a mistake to weaponize structural racism to support masking kids.

If masks slow COVID19 and improve long term outcomes, then they might help minority kids more than the majority kids. But if masks don’t actually improve long term outcomes– because all kids get COVID anyway, or because masks don’t slow spread— then masking kids disproportionately hurts poor minority kids. This study actually shows American society was happy to mask minority kids longer.

During the pandemic, poor people had to mask more than rich people. I mask on the public bus, but not when I drive my car. Workers mask when they serve you at a restaurant, while you enjoy life unmasked.

Let’s not convert a scientific question about whether masks slow viral spread into a referendum about who cares more about structural racism or socioeconomic disparities. Evoking this rhetoric is inappropriate for the New England Journal of Medicine. It is a shame editors allowed it. 

I suspect there is a reason why masking proponents want to tie their policy to structural racism. It allows them to claim their opponents aren’t just scientists who questions their methods, they are bad people. We cannot turn masking kids, and COVID-19 into a proxy war for political issues. We can’t make a scientific question a moral one just to shut down debate.

Dr. Vinay Prasad MD MPH

The New England Journal’s Disappointing Decision to Publish the Boston School Mask Study

By Tracy Beth Høeg, MD, PhD

I was surprised to see an observational study on school mask mandates, which was problematic as preprint, published in the New England Journal of Medicine.

Why did the NEJM publish this paper, which has many issues I will discuss below, when it runs counter to randomized data, and a nicely done regression discontinuity study from Spain? It also runs counter to a huge body of pre-pandemic randomized data finding limited to no effectiveness of cloth, surgical or N95 masks against influenza. 

Proponents of the study, “Lifting Universal Masking in Schools — Covid-19 Incidence among Students and Staff” believe the authors can infer causation (of mask mandates being effective against COVID-19 cases) because they used the Difference in Difference technique. I am going to explain why I don’t think the necessary assumptions are met to infer causality and why observational studies of school interventions have been so challenging in general. 

The study

This was a study of 72 public k-12 school districts in the greater Boston area during the 2021-2022 academic year including 294,084 students and 46,530 staff. They used a difference in difference analysis for staggered policy implementation to compare the COVID-19 incidence among districts that lifted or sustained mask mandates. 70 of these districts dropped their mask mandates, in a staggered by week shown below in the blue colors and 2 didn’t (shown in black).

The districts that dropped their mask mandates (n=70), did so in a staggered fashion by week in Feb-March shown below in the blue colors and, those that didn’t (n=2) are shown in black.

The first thing that jumped out at me when I read the study was Figure 1, which curiously shows the case rates started to increase in the blue (unmasking) districts independent of when they dropped the mask mandate. This suggests there is at least one factor independent of masking leading to the rise in cases in the unmasking districts. The second thing that stood out from this figure was the district that dropped the mandates at the second time point had higher case rates post lifting of the mask mandate than the district that dropped them first despite these districts having indistinguishable case rates prior to lifting the mandates. There is a lack of dose-response effect here.

These two points make a convincing case that the difference between masked and unmasked districts cannot alone be attributed to the masks.

The populations in the masked and unmasked districts are also different

The two districts that did not lift mask mandates were located in and around the metro area of Boston (black on this map) while the districts that lifted mandates were more suburban. As authors describe, “districts that chose to sustain masking requirements longer tended to have school buildings that were older and in worse condition and to have more students per classroom than districts that chose to lift masking requirements earlier. In addition, these districts had higher percentages of low-income students, students with disabilities, and students who were English-language learners, as well as higher percentages of Black and Latinx students and staff.”

There was also a pronounced difference in paediatric vaccination rates, with the district that unmasked second (& also had highest rates having the highest city/town paediatric vaccination rate and the district that never lifted mask mandates had the lowest paediatric vaccination rate.

The authors state, despite these differences, that causality can still be inferred from the masks because of their use of the Difference in Difference technique.

The difference in difference technique was originally used in econometrics as well and its usage dates back to the mid 19th century. It is also called the “controlled before and after study” and can be used to estimate the effectiveness of an intervention using observational data if certain assumptions are met.

One critical assumption is the parallel trend effect, which is shown below.

This means the difference between the control and treatment groups are constant over time prior to the treatment or intervention. It also assumes that only one thing changes at the time of the treatment that could affect the results – and that’s the treatment itself. Finally it assumes there are no other changes in behavior, policy or any other time varying differences between the groups that could falsely increase or decrease the appearance of effectiveness of the intervention (masks).

Just intuitively most people reading this will know that when schools change masking policies, other things are likely to change too. One of these things may be testing policies or reporting policies. Schools may also have changed masking policies or practices on their own during the study period (which I will get to in more detail below). Since these districts are spread out geographically, there will be changing differences in community case rates. There will also be differences in levels of immunity due to differing levels of vaccination and natural immunity.

Visual inspection is a useful way to see if the parallel trend effect is met. It also can affect your results by where you decide to start measuring the pre intervention period – shorter time period prior may be preferable for capturing recent deviations in the constant difference between groups. As you can see here, preceding the mask lifting, the difference between the mask lifters and controls is not stable. So this assumption is not met by looking at this particular time frame.

Second testing rates in the cities/towns were declining at different rates prior to the dropping of the mask mandates so this is a time varying confounder with inconsistent trend for the unmasked vs control group.

To get back to immunity levels, this will be varying and inconsistent across the control and mask lifting groups as the more highly vaccinated students (in the mask lifting group) would be expected to experience an early decrease in infection risk followed by decreased vaccine-related immunity, increasing their susceptibility to infection overtime. The masked group with lower vaccination rates may have had higher levels of seroprevalence which increased during the omicron wave. This may have provided the masked group with more durable protection going into spring. It would be fascinating to see the seroprevalence of these different areas of Boston over the course of the school year if anyone, and importantly, the seroprevalence rates were not included in this study.

Finally, to use the Diff in Diff technique to infer causation, there should not have been changes in masking policies or behaviors before or after the “treatment” time and it appears that at least one major change did occur that the authors I believe were unaware of (though I invite their comments!): a number of the schools who were stated to have lifted masking mandates in this study in the Feb-March period actually received a waiver and had already lifted their mask mandates prior to time 1, once they achieved an 80% vaccination rate. I understand a list is being compiled of the number of confirmed schools to which this applies.

Further, in the Boston study, the authors do not have information on testing rates, including at home testing, at the district level. This is a hugely important limitation and potential confounder- even with the diff in diff design. They state that in January 2022, the Massachusetts DESE strongly recommended replacing test to stay with rapid at home antigen testing. They state they do not know which programs the districts participated in – and this would not matter with the Diff in Diff design – if the policies or programs did not change over time– but we do know that though the MSESE had recommended discontinuing close contact testing in January, replacing those with at-home tests, the CDC continued to recommend testing of unmasked close contacts through the Spring of 2022 and we are not certain if any schools or districts may have continued to test unmasked close contacts either at school or at home. Further as at home testing became more heavily relied upon, the more affluent districts that dropped masked mandates may have been more likely to test.

For those who have spent time studying the epidemiology of COVID-19 cases in schools and children (I have; for example 1, 2), you will know there are many constantly moving parts that can lead to bias and changing biases and degrees if bias over time when evaluating the effect of a school intervention. My research group published a preprint of masking in two very similar districts in North Dakota (it is currently being revised after peer review and based on helpful outside feedback we received) and we discussed using the Diff in Diff method but I argued we could not assume there we no time varying confounders or other changes in policy or behavior that accompanied the mask policy changes and could affect the appearance of mask effectiveness… even if we could show a parallel trend prior to the change in policy.

As you can see, in our study, in two demographically very similar K-12 geographically adjacent districts in the same municipality in Fargo North Dakota, there was no difference in student case rates (y axis) while the districts had different mask policies (FPS, in blue, had a mask mandate prior to the vertical line at 1/17/2022 and WF in purple did not) or when they had the same lack of mask mandate after 1/17/2022.

Because student infection rates are so highly dependent on current community and prior immunity levels within the community, I would argue our findings of lack of major difference in mask vs no mask mandate districts is more convincing, yet still with many limitations due to being an observational study with many factors unique to the districts that can influence case rates.

But this also brings up the issue of publication bias, with many observational studies of school masking finding conflicting results. For example, in September of 2021, MMWR released a publication by Budzyn et al which found significantly lower increases in pediatric COVID-19 cases in counties with school mask mandates, but included only two weeks of in-school data from a limited subset of counties in the US. When my research group extended Budzyn et al’s analysis out to nine weeks and included 1832 counties, instead of the original 520, we failed to identify a significant correlation between school mask mandates and pediatric covid cases.

Interestingly our more robust analysis with the opposite conclusion was rejected by MMWR, but did go on to be published in the Journal of Infection. This points to the issue of some journals being more inclined to publish findings that align with their beliefs: another reason we really should not be using observational data to justify recommending or mandating masking, when we have some randomized data finding little to no effect of community masking, which is consistent with randomized data from influenza and there are obvious downsides of recommending or mandating especially children continue to mask.

Effect Size and Community Cases

In the Boston study, the identified masking effect size against cases that is implausibly high. They say the dropping of the mask mandates corresponded with an additional 11,901 cases, which was 33.4% of ALL cases in the unmasked districts. Among the staff they found 40.4% of the cases to be attributable to the lifting of the mask mandates.

This is unrealistic considering most cases come from the community into the school AND we have a randomized study from Bangladesh failing to find any effect of either community or cloth masking in anyone under 50 (and that signal was modest, at around 11% decrease rate with surgical masks, which was uncertain, and no significant decrease with cloth masks). We also have a regression discontinuity design study from Spain which takes advantage of the fact that 5-year-olds don’t mask and 6 year old do and there was no significant discontinuity from age 5-6 as compared with other ages to suggest an effect of masking on case rates.

Additionally, the authors of the Boston study made the difficult-to-understand choice of “consider[ing] community rates of COVID-19 as part of the causal effect of school masking policies rather than a source of bias” in other words they saw community case rates to be a result of school masking policies/school case rates rather than community case rates to be the major source of school cases. A large body of research has suggested the opposite finding COVID-19 in schools is up to 10-20x more likely to come from outside of the school than from within. This includes a study from the UKwhere children <12 were not masked.

But they did plot the results of school COVID cases vs community covid cases and, as you can see here:

School case rates had a similar relationship to city/town case positivity rates in all districts, with all school case rates similar in relation to that of the community, which speaks against any large impact of school masking. Further, it is unclear why cases would be presumed to be coming from the school to the community with the school peak lagging the community peak in two of the districts or why any difference seen in the masked district would be presumed to be due to masks when the March 17 and the did not lift groups appear so similar in the difference between school (black) and community  (orange) case rates. Looking overall at how much the mask district differs from the community compared with the unmasked districts, it’s clear the difference is modest— and of course may not be attributable to masks!

Even in light of the additional supplementary analyses and information (I am not presenting every single analysis and figure here!) my critique above still holds. I am trying to keep my explanation of the limitations of this study as simple and concise as possible Though I want to acknowledge all of the hard work and though the authors put into the analyses. Also, I welcome critique on critical points anyone feels I did not mention!

Discussion & Limitations

In the Discussion, the only limitations they list is the lack of information on district testing and that this was as study of mask mandates and not masks. While these are appropriate to mention, they did not spend time addressing the limitations above. Instead they spend time discussing structural racism and educational inequities, which are very important topic, but as this was not a study looking at addressing inequalities or structural racism and, for the reasons above mask policies could not be proven as causal in the decreased cases in the masked districts, let alone a solution to systemic racism stating, “ universal masking may be an important tool for mitigating the effects of structural racism in schools” struck me as a very odd conclusion for this study!

If we are considering structural racism and educational inequalities, they also failed to weigh the known downsides of continued making of children. Beyond the obvious fact that children seeing their friends smile and understanding them and as vectors of disease have value, research in this topic has already found children with hearing impairment to have impaired word recognition in settings with mask wearing. Even children without hearing impairment have been found to have reduced word identification particularly in a noisy environment when the speaker is masked.  Face masks also appear to impair recognition of emotions, trustworthiness and perceived closeness and may “undermine the success of our social interactions.”  These are drawbacks that need to be weighed… covid is for most children a small threat at this point and very far from the largest threats they face to their health and wellbeing.

So why was this study published in the NEJM with its limitations and implausibility when COVID-19 is a diminishing threat to children, and we have higher quality data that contradict their findings? I’ll leave that to the readers of Sensible Medicine to discuss.

Reposted from the Sensible Medicine Substack.

A Level-Headed Look at The Florida Vaccine Study


Last Friday October 7th, Dr. Joe Ladapo, Surgeon General of Florida, released a vaccine safety analysis along with updated guidance from the Florida Department of Health. The press release stated Dr. Ladapo “recommends against males aged 18 to 39 from receiving mRNA COVID-19 vaccines” has caused, predictably, quite the controversy. As full disclosure: I am someone who has been working as a consultant epidemiologist for the Florida Department of Health, who knows the Florida Epi team and is friends with Dr. Ladapo. At the same time, I was not one of the authors of the study, and I will be expressing my opinions.

Today, we released an analysis on COVID-19 mRNA vaccines the public needs to be aware of. This analysis showed an increased risk of cardiac-related death among men 18-39. FL will not be silent on the truth.


Press Release:

— Joseph A. Ladapo, MD, PhD (@FLSurgeonGen) October 7, 2022

Joe’s tweet, announcing the study results and new guidance now has over 90k likes and was accompanied by the additional information: Their “analysis found that there is an 84% increase in the relative incidence of cardiac-related death among males 18-39 years old within 28 days following mRNA vaccination. With a high level of global immunity to COVID-19, the benefit of vaccination is likely outweighed by this abnormally high risk of cardiac-related death among men in this age group. Non-mRNA vaccines were not found to have these increased risks”

First, let’s look at this study:

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An 84% increase definitely sounds scary. But 84% increase from what? Many assumed this was compared with unvaccinated controls, but actually this was compared with other 18–39-year-old males who had also received either one or two doses of mRNA vaccine and also died… but just died later than 28 days after the vaccine but no later than 25 weeks.

Both on Twitter and in the mainstream media, people were quick to try to criticize the study design for inappropriate controls or for lack of information on benefits of the vaccine. But the so-called “self-controlled case series (SCCS)” method has a very smart built-in control group of only people who have experienced the adverse event and is simply not designed to assess benefits.

The SCCS method was actually created to assess vaccine safety. It was first introducedby Paddy Farrington, Elizabeth Miller and team in The Lancet in 1995 as a way to look for association of the adverse events of febrile seizure and immune thrombocytopenia from DPT and MMR vaccines. 

It is a well-established epidemiologic method for evaluating safety and has been used numerous times already to evaluate the Covid-19 vaccines, in the UK (1,2), France and Nordic countries.

The idea of the SCCS is delightfully simple in that it assesses whether or not the risk of a certain adverse event (in the case of the Florida study “all cause mortality” or “cardiac-related mortality”) occurs more often than expected shortly after vaccination compared with baseline risk.

An unvaccinated control group was not necessary and the usual confounding variable of differences in health between vaccinated and unvaccinated disappears with this method. It’s a good alternative method to explore safety signals when you can’t get adequate information from randomized trials.

But what did the Florida study actually teach us?

It taught us there was a higher-than-expected rate of death in the first 28 days after their last dose of mRNA vaccine in 18–39-year-old males by 84% compared with weeks 4-25 post-vaccination. It did not prove this was due to the vaccine. 

It is noteworthy that this increased relative incidence in young males was not seen in other groups besides the >60-year-old males post-mRNA; this argues against this signal being due to people being sicker/hospitalized at the time of vaccination (though, the study may have lacked power to detect the signal in other groups and the authors could have provided more information on location of vaccination or provided other information to provide information on the underlying health of newly-vaccinated individuals, which I will discuss below).

Just using the unadjusted raw numbers, one can calculate the expected numbers of deaths in the 18-39 year old males post mRNA vaccine would have been 10 instead of 20 the first 28 days if risk were equal over the entire 25 weeks, so the signal we are talking about is 10 extra deaths total and an approximate doubling of expected number of cardiac-related deaths proximal to the vaccine (I spoke with Joe about the 84% reported and this was arrived at adjusting for seasonal variation in death rate). However, given the wide confidence intervals, this may have been just 1 or 2 deaths away from expected… so it’s a small number of deaths and a very uncertain signal.

The Florida study’s findings were inconsistent with a very similar UK preprint study. The UK analysis using Office of National Statistics data looked at young people ages 12-29 who all died post vaccination did not find a signal of increased risk of death in the first 6 weeks post-vaccination compared with the second 6 weeks.

The UK study did not look specifically  at the mRNA vaccines in young males. Also, the practice in the UK is to space the two vaccine doses by 12 weeks. The follow up period was shorter, which is important in a SCCS as the use of different risk and baseline periods can greatly alter the results. For example, what if the true vaccine risk period extends to three months post-vaccine and the UK study simply compared two periods of nearly equal risk? What if the risk period only lasts only a week and it was watered down?

On the other hand, confounders could also have been in play in the Florida study. What if some external factor unrelated to the vaccine decreased young males’ chances of dying due to CV disease in Florida during the baseline period?  For example, what if some of the young males actually had missing death registrations from the end of the 25 weeks? It would be nice to know if Florida ran tests to look for temporal biases and inconsistencies.

In a very nice, large Nordic SCCS of Covid-19 vaccine safety, they compared 28 days post vaccine with a pre-vaccination period. They did not specifically look at cardiac death and the included population was almost entirely over 50 years old.

They examined several outcomes, which appeared significantly increased post-vaccination. Relevant to cardiac risk, they found a borderline increase in corona artery disease (CAD) from Moderna only. One would not expect CAD to develop in a brief period after vaccination, but underlying disease could have been brought to attention due to new complaints of chest pain, palpitations, shortness of breath etc. 

(Getting back to the Florida study limitations, Dr. Panthagani made the good point that not all ICD-10 codes that cause cardiac death were included in the Florida study; specifically, ischemic heart disease was missing, though the explanation may have been as simple as ischemic heart disease is unlikely to develop shortly after vaccination due to the vaccine. So perhaps the exclusion of this particular code by the Florida team was appropriate.)

The Nordic study also identified a very strong signal for central venous sinus thrombosis (rate ratio of 12), which is a well-known safety signal by now, as well as other signals shown above related to the AZ vaccine. For the mRNA vaccines, the most notable signal was an increase in intracranial hemorrhage post Moderna vaccine (RR 2.19; adjusted p <0.001) in the 50 and older age group, which they say should be, among other potential findings, explored in future analyses. They highlighted the uncertainty around this finding as they found overall an elevated risk of hip fracture post vaccine in the mRNA vaccines with a rate ratio of around 2. While the authors conclude this elevated rate of hip fracture post-vaccine suggested poorer health around the date of vaccination, if patients were feeling unwell or dizzy post-vaccination, falls leading to hip fracture may have actually been due to the vaccination, so I am not sure this was the ideal way to detect confounding. But the potential of newly vaccinated to either be more or less healthy than the baseline period is an important potential confounder in SCCS studies.

Furthermore, the Nordic and Florida studies ran a large number of tests, and if a p value of <0.05 is used this would mean 5% would be significant just by chance. You can see above that the Nordic study corrected for this using a “false discovery rate adjusted p-value”. Florida could have considered such an adjustment for running tests in so many demographics but did not.

On the other hand, the opposite may be true. There may have been a true difference in outcomes in more groups in the Florida, but, because the number of total deaths were so small, the study may have failed to detect some true signals.

Finally there is the issue of a missed Covid diagnosis in the Florida study. The research team excluded people who they knew had COVID-19 through their medical records or death records but could not rule out undiagnosed Covid before or after the vaccine. This is a potentially important confounder. In other words, a young man could have gone out for a vaccine and caught Covid a couple days later and this may not have shown up in his death certificate or health record.

So, where does this leave us, the readers of Sensible Medicine?

We are left with a Florida study with a high degree of uncertainty that found 10 deaths (9 with their seasonal adjustment) above expected in the 28 days post mRNA vaccine among males 18-39. This is a signal which has not been found previously with the SCCS method in arguably better studies. A significant correlation with cardiac arrest calls and rollout of first and second doses of the Pfizer vaccine has been seen previously in Israel, in a study with small numbers.

And the demographic found to be at risk in the Florida analysis is known to have elevated risk of myocarditis post second dose as high as around 1/2000 range per Kaiser Permanente and as high as 1/1200 per Ontario data (when not spacing doses out and mixing Pfizer and Moderna). We know of deaths caused by vaccine-related myocarditis have been  reported in the peer reviewed literature, including in the NEJM.

The politicization of the topic can distract from the big question: Should young healthy people continue to get vaccinated/boosted against Covid? Or specifically, how many doses of mRNA vaccine should healthy 18–39-year-old males get and based on what? Should recommendations for previously infected be different?

My own research group found mRNA boosters carry at least 18x the risk of severe adverse event as hospitalizations from covid they prevent at a population level for people 18-29. For males one can expect on average 1.3-3 cases of post-booster myocarditis per covid-19 hospitalization prevented. A large Nordic study in JAMA Cardiology found post-vaccination myocarditis can occur up to 28x more frequently than post-Covid myocarditis in males 16-24 with the Pfizer-Moderna combination without increased interval between doses.

Denmark, Sweden and Norway have all stopped offering boosters to people <50 unless they are found to be at high risk from Covid. Last year, numerous countries recommended against using Moderna in males <30 due to increased cardiac risk.

The debate over Covid vaccine safety and benefits has been uniquely polarized in the United States, often involving personal attacks based on political affiliation. It is worth noting that the parallel debate has been largely civil in Scandinavia and that the recommendations to not continue to vaccinate young healthy people are largely accepted by most doctors and reseachers there. In Scandinavia, all along there has been open, transparent debate about pros and cons and side effects of vaccination types and number of doses in different demographics. There, because people remain trustful of public health authorities (with good reason), they are also less likely to jump to irrational fears about vaccine side effects.

Attacking physicians or scientists for spreading supposed “misinformation” is not the solution. Young scientists should not be fearful of reporting their results if they don’t fit with the current narrative or might be viewed as “political”. Or even worse, scientific journal editors should not avoid publishing certain findings for fear of online repercussions. If the public sees silencing and censorship, they fear an important truth is being hidden.

I hope we can get beyond the idea there are heroes and villains in the Covid pandemic and Covid vaccination story. We are setting a precedent now for how online scientific debate will happen in the future. So let us respectfully and openly discuss vaccine risks and benefits as if we were sitting in the same room together, all simply trying to solve a problem and give good individualized public health guidance.

In that vein, let’s debate! What did I get wrong in my analysis of the study and what do you have to add?

Reposted from the Sensible Medicine Substack

Sacrificing Children’s Health In The Name of Health


A look at the US’s Counterproductive Covid Policies and why Scandinavia did Better

Recently an article in the Swedish press by Johan Anderberg asked readers to imagine a scenario:

“We Swedes should play with the thought that it could have been us – that it could have been our kids that had had their schools closed, that it could have been our kids that for multiple quarters were forced to go to school with a mask… over the entire world, little children were forced to wear masks, eat their lunches outside in the cold and forced to take rapid tests.”

It is thought-provoking for us Americans to see someone from outside the US describe the harms inflicted upon our children during the COVID-19 pandemic.

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I added a picture frame to the photo from the article because I imagine one day, in the not-too-distant future, a photo like this will be on display in a museum of Covid-19 mistakes and absurdities. Historians, social scientists, ethicists, film-makers, lawyers, economists, great-grandparents and many others will look back on the pandemic and ask “How was it that Sweden, and to a great extent Denmark and Norway, were able to get it right with children?”


Sweden never closed primary schools and Denmark and Norway had brief, transient closures; they never masked children under 12 and free childcare was always available. Children always had a safe place to go throughout the pandemic. Disruptions to normalcy were minimized.

I suspect we will learn Scandinavia’s compassionate decisions about child policies during the pandemic had less to do with science than cultural commitment. It was clear early on that children were mildly affected by covid and were not primary driversof the pandemic. However, when Sweden chose to keep primary schools open and in Denmark and Norway reopened schools in April 2020, it was unclear exactly how well it would go.

Data from the Center for Global Development published June 12, 2020.

We then quickly learned from Europe’s experience in the Spring of 2020, “closure or not of schools had little if any impact on the number of laboratory confirmed SARS-CoV-2 cases in school-aged children”, and my own research and others showed this to also be the case in public and private schools in the US.

The below figure shows excess mortality (överdödligheten) in Europe in % by country in 2020 and 2021 with the country that dared never close schools, Sweden (Sverige), ending up near the bottom, above only Norway and Iceland.

The value of a normal childhood

In Scandinavia, the threshold for disrupting normal childhood seemed to be much higher than in the US and Canada.

In Sweden, it’s unconstitutional to close schools. They have a concept is called “skolplikt” where all children have the right to public schooling.  The head of the ministry of education, Anna Ekström, referred to this in the Swedish decision to not close schools: not only that all children have a right to go to school but moreover “school plays a very important role in children’s lives.” Denmark had a 6-week closure of primary schools but then famously opened outdoor theme parks, such as Tivoli Gardens, for outdoor classes in April of 2020. A society-wide effort was made to avoid, as much as possible, the pandemic interfering with children’s lives. Something similar could have been done in the United States. Outdoor sports and playgrounds could have remained open all along. In some fashion or another, schools could have re-opened in the Spring of 2020. Even in times of fear and uncertainty, should we not feel an obligation to be creative for our children?

Betrayal of the precautionary principle

Recall: school closures, sports closures, masking, asymptomatic testing, school-based vaccine requirements.  While some argued these were precautionary, the precaution was backwards. The harms from missing these events were not given due consideration.  I believe the burden of proof should have always been on showing that the benefits of these interventions outweighed the harms. None of the above passed any sort of rigorous or thoughtful risk benefit analysis in the US or elsewhere. The way we viewed public health in children strangely turned upside down during Covid-19; children have always been an ethically protected group. This means they should not be subjected to unnecessary harms without known benefits. But in the US, they inexplicably faced the harshest restrictions of any age group.

The last couple of years, I have been extensively involved in researching school mask mandates. Although ongoing research from SpainFinland and two studies I was senior author on failed to find benefit of student mask mandates, these mandates continued many places. This is despite the evident harms to communication and connectedness and learning. Many children will now also grow up with a distrust of public health because of being asked to mask for years for no evidence of benefit.

On September 10th, 2021, Denmark dropped all Covid-19 restrictions on society and Norway would soon follow suit. There was an article celebrating a return to normal school life and how important it was for children to thrive and have normal routines.

“It’s no longer about stopping the spread- children should thrive” read the Politiken headline on September 6th, 2021.

Vaccinating children

Scandinavia returned to normal schools without ever require children to be vaccinated to attend. Though a coronapas was temporarily adopted, Scandinavia now has now dropped all societal vaccine requirements. This decision was based on worldwide research that COVID-19 vaccines do not lower transmission risk and, at best, delay infections (by a matter of weeks to months).

The main benefit of vaccination is to reduce risk of severe disease. While the benefit seems clear in the average previously uninfected older adult, the benefits are much less clear in children. In fact, 1) we have no evidence that vaccination will lower the risk of severe disease in previously infected children and, 2)in healthy children without prior infection, the harm of the second vaccination dose from myocarditis alone may outweigh the benefits in healthy children. I want to acknowledge that the risks of myocarditis in younger kids <12 is lower than the risk to boys 12-28, for instance, but it is not zero, and a careful undertaking of risk benefit balance, particularly as kids have high prior immunity, as novel variants become de-coupled from mis-c, has not been undertaken.

Scandinavia more readily adapted policies that matched the evidence. Sweden never recommended mass vaccination of 5–11-year-olds. Norway has said prior infection should be considered equivalent to vaccination in children and always made child vaccination optional. The Director of the Danish National Health Institute (Sundedstyrelsen) in fact stated this June that vaccinating children under 16 was “a mistake.”

It is frustrating that the CDC and American media do not discuss Scandinavia’s differing policies for vaccinating children. Instead we are once again an international outlier in using highly uncertain data to recommend boosters in all children 5 and up and infant and toddler vaccines. This is another example of betrayal of the precautionary principle and there is no public health rationale to stifle discussion around weighing adverse vaccine effects vs benefits in children.

My experience as a dual citizen physician scientist mom

Through my personal lens as a physician epidemiologist extensively involved in researching many of the above topics: school transmission, sports closures, testingmasking of children and risks and benefits of mRNA vaccination in adolescents. With largely reassuring results about covid’s risk to children, or lack of effectiveness of school mitigations, the results of these studies have only been accepted very slowly in public health and academia. Perhaps it is my time living in Denmark that made me so incredulous our American society did not err on the side of allowing normalcy for children in the first place rather than waiting for conclusive evidence that it was okay to stop doing things to them.

It was likely a primitive mother instinct that prompted me to start sounding the alarm on the harm of school closures in the Spring and Summer of 2020. I witnessed Scandinavia successfully reopen their schools and simultaneously saw the way my own children and their friends lost so many things in life they loved including hope and a sense of what would come next. It was my background as a physician and scientist in Denmark that convinced me early on this was not just about the covid response but a much deeper issue in the way that America views and treats children.

My own experience as a young physician mom showed me first-hand the stark differences in the Scandinavian and American societies when it comes to policies around mothers and children. At age 28, I had matched into my first-choice ophthalmology residency program in the US but – 1 week before start – found out I was pregnant. My Danish boyfriend (future husband) had matched (before we had met) at a residency program in another state. I started my dream residency program, but having a child with only 15 days’ maternity leave, without family or help nearby was an incredibly overwhelming prospect. Someone in the program leadership suggested I have an abortion. I simply could not fathom this could be the best solution. I did what, to me, just one year earlier would have been unthinkable: I left the residency position, risking my entire medical career.

I was lucky because it worked out. I ended up moving to Denmark with my husband and was able to quickly start practicing medicine and went on to complete a PhD in epidemiology and public health, while having plenty of time to be a mom!

Mothers in Medicine

I wonder how many women physicians in the US give up their medical careers because of their children. Who are these mothers that never become practicing doctors or never even start training because they know how hard family life would be? I learned by moving to Denmark that medical training doesn’t have to be hard on new moms. You can have a respected career as a physician and scientist and only work around 37 hours a week and have 9+ months of maternity leave, free healthcare, 6 weeks of vacation, many holidays off and get paid to do a PhD on top of that (all you need to do is learn Danish and marry a Dane!). I think because of these options and support,physicians in Scandinavia have a more family- and community-centric way of looking at the world.

Though it may not be immediately obvious, this societal approach to supporting parents is tied to Scandinavia’s decisions about school closures. In most cases, it is in children’s best interest that their parents spend time with them when they are young. Further, remote school would mean a parent needing to stay home, but with around 80% of mothers working in Denmark for example, not having a place for children to go during the day was incompatible with both women’s and children’s rights and the entire Danish society. In the US, families with single or two working parents faced an incredibly tough decision during the pandemic: if their public school was closed and they could not afford an open private school, either a parent would stay home, a grandparent would be put at risk of covid, or the child would be at home alone. It’s not surprising in the US 45% of mothers were not working during the pandemic, which disproportionately affected women of color. Furthermore, children with parents who could not afford to stay home were less likely to be able to attend remote school. In Detroit, where Zoom school dominated for over a year, 70% of kids in public schools were chronically absent. School closures induced harm inequitably and for no clear benefit. The damage done to these children may persist for a generation or longer.

Encouraging scientific debate

Why did this happen? Debate was stifled and decisions were left in the hands of few. Those in charge may have been fearful of getting covid, unfamiliar with how to best manage this type of pandemic and faced political pressure to promote certain policies. Spreading a fearful message may have also resulted in more fame and attention. The entire news narrative was indeed more hopeful in Europe than the US. This was particularly striking to me in Danish news where fear mongering was nearly absent. This may have been a result of diverse voices of various political views being able to contribute to the conversation, while they were silenced in various ways in the US.

Unlike the recent trend in the US, debate is and was encouraged in medicine and the media. Recent debates in Danish newspapers have included pros and cons of vaccinating children for COVID-19 and whether or not the Swedish or Danishapproach to managing the pandemic was better. I would love to see debates like these in the New York Times and other mainstream media. In Scandinavia, physicians and scientists don’t risk losing their research funding or jobs for questioning the dominant narrative. Indeed, many American physicians have reached out to me and my friends about feeling forced to express certain opinions they don’t hold.

Physicians as servants of the people

In Scandinavia, physicians are respected but simultaneously are seen as entirely normal(consistent with the Scandinavian concept of janteloven). As a result, medicine is much less patriarchal and public health more a partnership with all society.

Along with this has come an accurate representation of Covid’s risks to children which includes reporting deaths and hospitalizations in children due to covid rather than simply with covid. Risks of long Covid to children have not been needlessly exaggerated.

We have all watched the US become increasingly fearful of disease and reliant on expensive, and, at times harmful, medical and scientific solutions to complex problems. Hyperfocus on the avoidance of disease leaves less time for play, sports, music, art, togetherness and the outdoors, all of which can make childhood healthy if nt magical. Testing, quarantines and masks needlessly interfere with these. People do count on us physicians to not forget what health actually is. One need look no further than children’s physical activity levels during the pandemic to see a striking example of how much of the world has failed. There was, on average, a 20% decrease in physical activity worldwide in children during the pandemic, while there was no such decrease among children in Sweden.    

The failed intervention of tying swings together would have been unthinkable in Scandinavia. It is the opposite of hygge or good public health. Photo by @politicalmath

In the end, much of the world unfortunately emulated the US and Canada’s school closure policies and attitudes towards children. As a result, 150 million additional children worldwide are now living in poverty and millions have not yet returned to school after many spent over a year not being allowed to leave their homes. Many more articles and books will be written on this topic: the unhealthy and inequitable actions imposed on children in the name of Health and Equity

It’s not over

California will likely soon be passing a bill into law which will require schools to continue covid testing in children. Estimated to cost $1.5 billion for just the first year, this law will keep children unnecessarily out of school, sports and time with friends for a third year.

Children 12 and older will be required to be fully vaccinated to attend school in Washington DC. Again, with only evidence of a brief possibility of reduction in transmission potential, and such a high rate of previous infection, why the choice for children to be vaccinated will not be an individual one. Some children will needlessly harmed by myocarditis or other side effects and others kept from school for not being vaccinated.

Children will still be required to mask in some districts again despite lack of good evidence of benefit. For some kids, there is no end in sight.

As Dr. Joseph Marine, Johns Hopkins Professor of Medicine, said : “Today I saw in my hospital lobby a woman struggling to put a useless cloth mask on a blind (resisting) 3 year old to comply with a Johns Hopkins mask policy. This policy has no rationale, no good evidence and no endpoint. A moment to be embarrassed for my profession.”

As this pandemic ends, doctors and public health officials should 1) speak out against ongoing policies that harm children more than help them in the ways that they can and 2) admit mistakes were made and be a part of defining what they were.

Norway, for example ,has found in their pandemic investigation that even the relatively brief school closures in their country did more harm than good, citing negative impact on children in terms of “less play, learning, attention and well-being”.

The Norwegian government interviewed children about how they felt about school closures and Live Sæther age 7 said the first day she went back was “probably the best day of [her] life”

If physicians and public health officials in the US remain silent and fail to admit past mistakes, harmful policies will persist or resurface in the next pandemic. Why wouldn’t they, without us defining what went wrong or creating an ethical framework to prevent the same mistakes?

I and other physicians and scientists are working to set an agenda for an investigation. Also, at Urgency of Normal, we are starting both a children’s rights group and a physician’s professional organization focusing on protecting children’s rights and well-being, free from political or special interest group influence. It will also be a place where we physicians see each other as allies, who are allowed, even encouraged, to disagree.

It is not the full answer to the complex problems above, but as Lao Tzu says, “a journey of 1,000 miles begins with a single step” and we owe it to our children to start with them.

Reposted via The Author’s Substack