Opening schools.

Science article.

Bolding mine.

Update? So far, weeks later, no new surges in countries that have opened schools.

There is also this Science article from Tuesday: “Why do some COVID-19 patients infect many others, whereas most don’t spread the virus as all?”

  • Most of the discussion around the spread of SARS-CoV-2 has concentrated on the average number of new infections caused by each patient. Without social distancing, this reproduction number ® is about three. But in real life, some people infect many others and others don’t spread the disease at all. In fact, the latter is the norm, Lloyd-Smith says: “The consistent pattern is that the most common number is zero. Most people do not transmit.”

That’s why in addition to R, scientists use a value called the dispersion factor (k), which describes how much a disease clusters. The lower k is, the more transmission comes from a small number of people. In a seminal 2005 Nature paper, Lloyd-Smith and co-authors estimated that SARS—in which superspreading played a major role—had a k of 0.16. The estimated k for MERS, which emerged in 2012, is about 0.25. In the flu pandemic of 1918, in contrast, the value was about one, indicating that clusters played less of a role.

Estimates of k for SARS-CoV-2 vary. In January, Julien Riou and Christian Althaus at the University of Bern simulated the epidemic in China for different combinations of R and k and compared the outcomes with what had actually taken place. They concluded that k for COVID-19 is somewhat higher than for SARS and MERS. That seems about right, says Gabriel Leung, a modeler at the University of Hong Kong. “I don’t think this is quite like SARS or MERS, where we observed very large superspreading clusters,” Leung says. “But we are certainly seeing a lot of concentrated clusters where a small proportion of people are responsible for a large proportion of infections.” But in a recent preprint, Adam Kucharski of LSHTM estimated that k for COVID-19 is as low as 0.1. “Probably about 10% of cases lead to 80% of the spread,” Kucharski says.

That could explain some puzzling aspects of this pandemic, including why the virus did not take off around the world sooner after it emerged in China, and why some very early cases elsewhere—such as one in France in late December 2019, reported on 3 May—apparently failed to ignite a wider outbreak. If k is really 0.1, then most chains of infection die out by themselves and SARS-CoV-2 needs to be introduced undetected into a new country at least four times to have an even chance of establishing itself, Kucharski says. If the Chinese epidemic was a big fire that sent sparks flying around the world, most of the sparks simply fizzled out.*

There is a persuasive case for opening up primary and secondary schools anyway even if students are infectious; we can’t keep students at home indefinitely without impacting their development, parents who are working at home need the time and space to be able to do their jobs, and for many students school lunches are their one hot and reasonably nutritious meal as well as the support school may provide to students with bad domestic environments. And short of a vaccine, we are going to have to facilitate controlled contagion so that people in low vulnerability cohorts can be exposed and hopefully return to work and other activities with assurance of low risk. Allowing parents the option to send their children to school and then monitoring for signs and symptoms (and even periodic antigen test sampling) would give a way to control and track exposures.


Oh wow, thank you for this DSeid and Stranger. It is definitely great news that there have been no new surges due to opening schools!

I’m also very intrigued by the idea that many/most people don’t transmit. (Enough that it might be worth putting in its own thread?) It sounds like we might have lucked out in a lot of ways with COVID-19.

There will definitely be an increase in cases with any relaxation; that is inevitable. The point is being able to monitor and make reasonable predictions of the effects of of such relaxations. Short of a vaccine, we’re going to have to accept spread of contagion and a certain marginal level of mortality; the point of “flattening the curve” is to prevent cases from exceeding the capability of the health system and get a handle on the epidemiology and pathology of the virus so we can better control and treat it.


As noted previously, the evidence for closing schools have always been rather ambiguous, and it does not appear that the decision to close them was based on solid science.

Speaking as a public school teacher - Closing schools was the right thing to do. The students are disease-ridden plague-monkeys in the best of times. Now…

This link is archived and updated pages provide more information on school closures and the steps needed to re-open. They are no longer expressing any indication that closing schools was unnecessary. They really didn’t in the first place, only saying it didn’t seem to help in Hong Kong. How old IS that link anyway? There’s no date listed.

Closing the schools was never the right thing to do. The damage this virus can do is strictly short-term. A few years from now, it’ll be history. But the damage done by closing the schools will still be haunting us decades from now.

Gov. DeWine of Ohio has already “reassured” parents that schools will not be doing anything to make up for lost time, because remote learning has been just as good as open schools, for all students everywhere in the state. Which is of course patently false; many students haven’t had any remote schooling at all, for various reasons (including that many schools followed DeWine’s advice).


Buying a smoke detector is never the right thing to do. The damage from a house fire is strictly short-term.

I think I first saw that source a couple of months ago. (It predates NYC closing schools, since I first saw it in that context.)

All I took from that link was that the evidence was always ambiguous. The OP of this thread seemed to be suggesting that emerging evidence may point to closing schools as having minimal impact, and my point was that it doesn’t appear that actual evidence ever pointed to closing schools to begin with.

That CDC guidance was that there’s a role for closing schools where the healthcare system is being overwhelmed or mass absences among the school staff and such, but otherwise pointed to evidence that there was no difference, based on the approaches of different countries.

Closing the schools was always the right thing to do. Because with the dearth of solid information we had early in this pandemic, it was better to be safe than sorry.

They are, but- they arent practicing social distancing or wearing masks anyway.

Just on a short walk yesterday I saw two groups of teen/tween kids, ten playing basketball, eight doing skateboarding. No masks, no social distancing, no parents.

unclear if students or teachers and by timing seem to not be from school transmissions.

EU consensus is so far so good.

“Schools reopening has not triggered rise in Covid-19 cases, EU ministers told”

Assuming that this bug would behave like influenza was reasonable. Erring to caution even as it became clear it does not was defendable. But the harms have been very large and at this point the burden of proof is on the need to keep imposing the harms upon the children.

Moderator Note

Keep it civil in this forum. No warning issued, but refrain from remarks like this directed at other posters.

QZ Moderator

At the time that various states made the decision to close primary schools (and many colleges and universities elected to send students home) we had little direct epidemiological knowledge of the SARS-CoV-2 virus except for what was being reported by the WHO based upon data provided by China on the Wuhan outbreak, the catastrophic epidemic being observed in real time in Italy and Spain (and mass graves being dug in Iran as seen from satellite images) and the unexpectedly rapid spread in North America and Europe, which gave disparate statistics that had led some people to hypothesize that we were actually experiencing a more virulent strain of the SARS-CoV-2 virus than the one responsible for the epidemic in Wuhan. This, combined with a lack of available testing even in countries with advanced health care systems and robust epidemic response infrastructures, created a lot of uncertainty about how the virus was being spread and who was spreading it. We now know that that was largely a result of inaccurate information and a high asymptomatic or pre-symptomatic infection rate but at the time official sources were quoting the R[SUB]0[/SUB] as 1.6 to 2.3 whereas even a fairly naive model that I cooked up over the course of a weekend in early March showed an R[SUB]0[/SUB] of at least 4 and potentially greater than 6 (and there is no way that professional epidemiologists weren’t coming to the same conclusions and just not voicing them). The current estimate is now 3.8 to 8.9 with a mean of 5.7, which means the virus is a lot more transmissible than the then-official statistics indicated, and estimates of case fatality rate were ranging from a fraction of a percent all the way up to 5% depending on whose country’s stats you looked at.

It is easy to say now that “damage this virus can do is strictly short-term” and “the damage done by closing the schools will still be haunting us decades from now” (I’m not sure I fully agree with either statement) but that can be readily turned around to say, “Students can make up for lost time but the virus kills forever”; and the calculation between loss of development time versus loss of life is not a simple or easy one to make. Dr. Birx, who was an early advocate of isolation measures (presumably including school closures) has had personal experience with this; her then-11-year-old grandmother brought home the H1N1 ‘Spanish Flu’ strain that killed her Birx’ great-grandmother and carried guilt about this with her for the rest of her life. If children were found to be effective carriers of the SARS-CoV-2 virus and infected adults en masse after passing it around in the unsanitary confines of schools, that could result in a mass epidemic outbreak that could easily overwhelm the health system. That it now seems that this is unlikely gives good confidence that opening schools will not result in uncontrollable contagion, and although children are not as ‘immune’ as once thought, the morbidity and mortality rates are sufficiently low that it isn’t a greater risk than exposure to influenza or other common viruses that affect children.

And I feel compelled to point out again that the response to this pandemic shouldn’t just be about “getting back to normal” as quickly as possible, but using this event as a learning experience for the next and potentially more virulent pandemic, which includes altering our educational, medical, and social systems to be able to cope with isolation measures and establish a more robust epidemiological surveillance system. People (myself included) keep using the term “unprecedented” to describe this pandemic, which is true in the context of modern history, but it is really modern history that is unprecedented in that we haven’t had a really unconfined highly transmissible epidemic since polio (except for HIV/AIDS, which people conveniently forget about because it is relatively easy to avoid in developed nations). The history of the world is rife with infectious epidemics sweeping through whole regions and decimating (or worse) the population. Smallpox swept through Eurasia innumerable times with casualty rates often exceeding 25%, and when it was transferred to the Americas as a novel virus the population there had never experienced, it cut through the native peoples killing so many we don’t even know what the fatality rate was other than that it was likely greater than 90%. We need to think not about what we can do to get back to work, school, and play next week, but what we can do to make sure the next infectious pandemic can be controlled without such massive disruption.


This is poor reasoning unimproved by any evidence whatsoever.

We know children are less affected by the virus. But there’s no solid evidence that they don’t spread the virus. And schools are not hermetically sealed capsules; school activity generates a lot of secondary travel and contact for both kids and adults that could lead to more spreading. Dropoff and pickup, extracurricular activities, fieldtrips, shopping, deliveries, increased socialization all create additional social mingling and points of contact.

There may come a time when we conclude that opening schools is the best of bad choices. But in the early days of a mystery pandemic with details still emerging, of course closing schools is the right thing to do. Even in hindsight we haven’t determined that it was the wrong thing to do.

My wife is an elementary school teacher, so she is keenly interested in this. We’ve been following developments in California, and all I can say is it’s going to be a mess.

Ideas being bandied about include: No recess. School only on alternate days for students (though teachers have to go every day). Students sit in the same seat all day, including for lunch. No prep periods (specialty teachers like PE, music, and science).

It should also be noted that while the majority of teachers are under the age of 65, there are some who may still be in vulnerable cohorts, as may be other staff and volunteers, notwithstanding the sheer number of people between 20 and 65 with no underlying conditions who have nonetheless presented severe cases of COVID-19. Keeping schools open for in-person classrooms is tantamount to forcing these people to remain exposed while other businesses are allowed or encouraged to allow workers to work remotely even there is no way that teachers and students can follow distancing guidelines. Teaching is already a financially undesirable occupation with many teachers leaving for other fields because of inadequate salaries or benefits, and forcing them to remain on-post in the middle of an epidemic is just going to exacerbate that exodus.

There is no question that online education is not the same as classroom instruction even for classes without a lab or physical interaction component and many students lack the facilities for online schooling but without testing and monitoring schools are natural nodes for contagion. Closing schools along with hair salons, barbers, restaurants and bars, concert venues, et cetera is an obvious and nearly obligatory first step in dealing with any wide scale outbreak until the epidemiology is better understood and there is good confidence in being able to monitor and control outbreaks.