Monday, July 20, 2020

Opening Elementary Schools Might Make Sense In Covid Time

The original post is this note from Dr. Hoeg.  Her reasoning, while sound at the time, might be faulty, in that the New York Times reports that children have been now shown to harbor large loads of the virus in their nasal mucosa - see here

From Tracy Hoeg MD PHD: (UC Davis)

I wanted to give an update on the research regarding COVID in children. 

I should back up briefly and state that I am a physician with a PhD in Epidemiology who became very interested in this topic when a colleague and friend of mine, Jennifer Kasten, MD MSc, wrote a systematic review of COVID epidemiology in children ( and found kids 12 and under *might be viral "dead ends", meaning they can get COVID but can't transmit to anyone else. This really captured my interest because this would make COVID very different from most respiratory viruses we know. Then in a physician's group dedicated to school opening, a physician researcher published a document for the group in which said she could identify 0 (zero) cases of certain transmission from children under 12 in the scientific literature and since that time Dr. Rutherford, UCSF Epidemiologist, has also been public about elementary-aged children being a "one way street" for infection - they get it but don't appear to transmit it, much, if at all. (UCSF Grand Rounds lectures are now available on YouTube for those interested in hearing him).

Last month, I did my own summary of the data ( and found evidence of the following:

*Very limited transmission if any from children ages 12 and under to either other children or adults

*Children appeared to be at least 10 times more likely to die of influenza than Covid and are more likely to be struck by lightning (I rechecked the CDC website today 7/13 and they are still reporting 3 deaths in children under 18 due to confirmed COVID; for comparison, there have been 185 deaths due to influenza in this population in the 2019/2020 season. If anyone has an updated death count in the pediatric population due to COVID, please share).

*Countries that reopened elementary schools as a first step in their country's reopening did not see an uptick in cases (these include numerous European and Asian countries, some of which are displayed in Figure 4. Reopenings not causing and uptick in cases is consistent with children not being a major vector for the disease. Figure 3 shows age of the source of the cases of COVID in Holland, with none ages 18 and under in their study, as just an example of these data. 

What have we learned in the last month?

1. We now have a generally accepted mechanism for younger children getting milder disease and transmitting significantly less than adults, which is paucity of ACE2 receptors in the respiratory tract compared with adults (this is the receptor SARS COV2 uses to enter the cells of the body). This could explain why children get COVID less, have milder disease (lower viral load) and are less contagious (if contagious at all). Yet another way COVID is unlike typical influenza!
(Figure 2)
2. Consistent with this was the study showing lower viral load (lower amount of the virus) in children up to age 18. (Figure 1). The original non-peer reviewed print of this article from Drosten et al was reanalyzed as per UCSF Grand Rounds and does indeed show significantly lower viral load in children as seen in image 1. 

3. This is great news for teachers and children, because not only are children significantly less likely to transmit COVID, but IF they do, the dose of the "inoculum" will be expected to be lower and there is mounting evidence (though inconclusive at this point) that the lower the dose of the virus you get, the less severe your disease will be if you even get symptoms at all ( This may be why Denmark and Norway were able to reopen elementary schools without any mask wearing in children (or adults for that matter!). Now if there IS mask wearing in the US by either children, adults or both, that would make both transmission even less likely and possibly the severity of the disease will be less if it does occur (interesting non peer-reviewed study showing inverse correlation between mask-wearing and mortality rate:

4. I am sensing many of your are STILL skeptical we can safely open elementary schools in the US. Well, thankfully we have really good data from the YMCA childcare for essential workers in the US, which has been providing childcare throughout the pandemic (our kids go there) and was even open in NYC at the height of the outbreak and they have had 0/>40,000 kids (ages 14 and under) contract COVID. They have also not had any outbreaks, though a few staff at different sites tested positive (presumably contracted from another adult per the above data) and quarantined so no more than 1 positive case a just a limited number of sites. Adults wear masks, kids don't, temperature checks at the door, each kid has a small "cohort" of kids they do everything with. More details can be seen in this article, but it shows that WE CAN DO THIS SAFELY in the US - even in areas hit severely by the virus and with truly minimal resources. 

Edit: The small cohorts in children may actually not be necessary and the data I am using to support this is guidelines for return to school in Holland in quotes below and from their Ministry of Health Website ( This model has worked for them:

"Children up to and including 12 years of age do not have to keep 1.5 metres apart from each other and from adults. This also applies to childcare and primary education.
Young people aged 13 until 18 years old (i.e. 17 years old and younger) do not have to stay 1.5 metres apart from each other. In secondary schools, this applies to all pupils, regardless of their age."

--I also want to briefly address the many "clickbaity" articles in the popular press lately about school and day care outbreaks. Specifically I will mention the school outbreaks in Israel where there were some infections in high school aged children but the "outbreaks" in the elementary schools were among adults only. Also, if you carefully look at the reports of day care outbreaks in our country, most appear to be involving staff that infect each other and, if kids are affected they are infected by the adults and are asymptomatic/have mild disease. I challenge you all to look at the articles coming from the popular press with the above data in mind and you will be surprised in the elementary age group that the adults appear to be the ones responsible for the outbreaks (though it is hard to get all of the info from those articles) and the ones who are severely affected by the disease.

--What are the bottom lines?

1. Kids 13-14 and below (likely around puberty) do not appear to be driving the spread of COVID. They rarely (one can never say never) transmit the disease. Tracing the source case with 100% certainty can be very challenging, but the data overall indicate pediatric transmission to be quite rare compared with adults.

2. Kids up to 18 years of age tend to get mild disease if any symptoms and death in this age group is less likely than getting hit by lightning. 

3. In school settings, adults can and will give to adults and kids, so teachers need to be socially distancing while at work. Adults also should be wearing masks and getting tested and staying home if they have symptoms. 

4. Data and guidelines from Holland suggest distancing among children <19 and="" as="" be="" been="" children="" countries="" div="" economy.="" even="" first="" has="" in="" it="" masks.="" may="" necessary.="" not="" of="" opened="" out="" pointed="" reopening="" scandinavia="" schools="" should="" step="" successful="" that="" the="" their="" these="" wearing="" without="">

5. I have previously discussed the many downsides of not having kids in school in person this fall: further entrenching socioeconomic disparities, job loss for parents who can't afford childcare worsening poverty and neglect, abuse of children (which will be underreported), lack of support for children with special needs, anxiety, depression and lack of physical activity and peer relationships in children. The list goes on and on. But I want this post to focus more on the science of the disease so it can inform our public policy decisions.

6. I hope the above data are reassuring. The more we know, the better we can tackle and live with this disease.

Edit: Now that this post has been shared hundreds of times (never imagined this), I want to say first of all, that I in no way am intending to detract from the seriousness of COVID-19. It is imperative our country get this disease under control -by social distancing, closing indoor businesses which are not essential, wearing masks, etc, but the above data at least suggest to me that children are not driving the pandemic; adults are. And I also want to say that a lot of what I shared above was recently discussed in the UCSF combined Medicine and Pediatric Grand Rounds lecture (an inspiration for me to write this to get this scientific info to the public). I encourage anyone interested in the above data to watch this recording of the Grand Rounds :

And this article about the above UCSF physicians' stances on reopening schools and transmission in children:

I welcome any data or questions you have. The science about COVID in pediatrics is evolving and we don't have all the answers (far from it), but I hope people can use the above data to help them make informed decisions about children's activities and school openings. 

Now in my OPINION- elementary school is an essential service of a country. All other first world countries prioritized opening their elementary schools BEFORE their economies. When one considers the number of couples or single parents who are essential workers, or now working again in the US, with kids too young to watch themselves - I ask you- where will they go if not to school? And will the alternative be better?  These children with either be 1. in school, 2. in a day care (IF their parents are privileged enough to afford this) or 3. neglected/potentially left alone at home and not learning and without their usual resources. It is our job together as American people to figure out what is in the best interest of all our children (regardless of socioeconomic status) - they are truly the future of our country and figuring how to open schools safely is infinitely more important than reopening Disney World (WHY is this open??). I hope we can use the above data and strategies of other countries (as well as our own YMCA daycares!) that have successfully managed this pandemic to guide us. Having NO plan for how to most safely open our elementary schools is not an acceptable modus operandi for our country.


Edit to add new data:

7/16: In Germany, a study of over 2,000 children: "Scientists from Dresden Technical University said they believe children may act as a “brake” on chains of infection."

7/16: Study performed by the Swedish and Finish Ministries of Health "closure or not of schools had no measurable direct impact on the number of laboratory confirmed cases in school-aged children in Finland or Sweden. The negative effects of closing schools must be weighed against the positive indirect effects it might have on the mitigation of the covid-19 pandemic."

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