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Reopening Schools? The trickiest balance between denial and alarmism, and Israel's experience.

Updated: Jul 30, 2020

This article describes Israels' experience with the pandemic, in which sudden and apparently careless opening of schools seems to have directly produced a second surge of COVID-19 that makes Israel one of the fastest surging countries the world after having it almost completely defeated in mid-May before school openings.


As of May 10, Israel had crushed the curve, dropping from a peak of just over 500 cases per day in early April down to just 10 cases a day in a country of >9 million people. They had the pandemic licked.


Rather than slowly opening schools with limited grades or reduced capacity, they quickly opened all of the schools, and look at what happened:



They now have experienced a second surge with daily counts >3x what they were in the first surge, and the exponential increase is continuing. Looking at test positivity rate, it is clear that this infectious surge is real, not an artifact of testing, and deaths are also now steeply increasing. The article highlights that somewhere around 50% of cases are spreading through schools, so that clearly seems to be a major factor.


If this is what happens with careless school openings when having 10 cases/day in a country of 9 million, what will happen in Harris County, that currently is experiencing 1000-1500 cases/day in a population of just over 4.7 million, or Brazoria County, that is currently experiencing upwards of 100 cases/day in a population of just over 370k, or Miami-Dade county with upwards of 4000 cases/day in a population of just over 2.7 million, if schools are carelessly opened?


Honestly, there is no precedent for this. During this entire pandemic, almost no place in the world has surged like Houston and Miami-Dade have been surging, and certainly no place has opened schools under those conditions, putting together groups of children from around the county together in rooms of 15-25, walking around hallways together, hopefully wearing masks but who knows with how much compliance, and in air conditioned buildings that hopefully have adequate ventilation and outside air flow, but who knows.


Schools have some of the factors that can contribute to rapid spread, including large groups of people spending lots of time together indoors in enclosed areas, perhaps inadequate social distancing, perhaps poor ventilation in some schools. A recent study in Korea found that while children 10 or under were much less likely to spread the virus than adults, they could still spread it, while children 10-18 seemed able to spread it as efficiently as adults. This raises concerns about viral spread around schools. This is alarming and raises questions about how we can possibly open schools safely.


This study counters discussion from others that suggest that maybe children don't spread the virus like adults do, including a commentary in Science here, or my previous post about a May review article here, and this Washington Post article that suggested that reopening did not produce surges. It is clear that keeping kids out of school is damaging to them in multiple facets, educationally, socially, psychologically, and for some kids school is a reprieve from an unhealthy home environment where they can experience good nutrition and safety. If it was safe as some of these reports suggest, clearly it would be better for children to return to school.


This excellent article from Science earlier this month reviewed reopening in many places around the world and talked about many different factors, as well as places that never closed schools. They were encouraged by the results, seeing that places that kept student groups small and requiring masks and some social distancing seemed to keep schools and communities safe, and that younger children seemed to rarely spread the virus to one another or bring it home. But the experts emphasize that success was not just about these steps, but also about how much virus was circulating in the community. Given a high virus level like in surging locations in the USA, opening schools will undoubtedly lead to school-based outbreaks. Even if the children tend to have good outcomes from infection themselves, if this contributes to an out of control surge in their community, it will invariably lead to greater infections in more vulnerable populations and potentially tax the medical system and lead to unnecessary deaths. This article also talked about several studies that suggested that children under age 18 are 1/3 to 1/2 as likely to contract the virus, and this disparity is even greater for younger children. Some impressions from those studies were that children younger than 11 or 12 probably don't transmit very much, but middle school and high school students may tend to have asymptomatic and mild disease but are still contagious and transmit as efficiently as adults, The article also discusses masks in school and what to do about testing -- it is a great read.


So what do we do in this country? It would be much easier if I would just pick a side -- to be a denier and say that kids won't spread it as much, and if they get it they will likely only have mild disease, and the cost of what they'd miss by not going to school is too great so they just need to go back. Or to be an alarmist and say that "no one should go to school until the county has 0 cases for 14 days" or some other unrealistic condition that will never be met, and suggest kids should just stay home until coronavirus is gone. It is so hard to try to find the happy middle between the two extremes! And in this case it is harder than with other settings.


What is clear to me is that there is no way that schools can safely open in surging counties. The viral level is too high. If a hybrid model with smaller numbers of students per class is used, with strictly enforced social distancing and mask wearing, and ensuring students, teachers and staff who are symptomatic stay home without fear of repercussion, with testing available to track cases growths to detect a surge early --- maybe. But in surging areas I'm not sure that can even be safe. those areas simply have to practice careful mitigation to get their numbers down to get more manageable levels before they can seriously consider broad reopening.


This tool by Georgia Tech researchers computes for each county the probability of at least one infected person among a group of N randomly selected people and is a useful tool for assessing the viral levels in a given county. From this tool, the probability of a random group of 25 people containing an infected person is 15% in Montgomery County, a suburban county of Philadelphia, 65% in Harris County in Houston, 74% in Brazoria County in suburban Houston, and 98% in Miami-Dade county.


Based on this, the idea of bringing together groups of 25 children together all day in classrooms in Harris, Brazoria and Miami-Dade county seems, um, problematic. Maybe in Montgomery county, it could be tried, but even then the social distancing, group size limitations, mask wearing, and isolation of those with symptoms and rapid testing are necessary to ensure that the groups at school don't spark or feed growing outbreaks. Recall that Houston had counts <40-50/day back in May when our model predicted a surge that would make Houston a national epicenter, and as predicted with lack of vigilance it surged to current levels of 1000-1500/day now. If other communities are not careful, it is possible for infections to start spreading out of control, so continual care and vigilance is necessary. Look at what happened in Israel.


I think of an infected individual as a spark, and a surge as a forest fire. We are in a pandemic, so it is unavoidable that sparks will be flying around, so the best thing we can do is make sure the conditions are not conducive to sparking of an inferno. Put in safeguards to limit the spread, and be ready to contain small fires from sparks so they don't ignite the entire forest. If there are too many sparks flying around, it may be necessary to reduce those sparks before bringing them into potentially combustible environments.


My thoughts are that already surging locations clearly need to start online until their cases counts are down to a lower level. But there is a ditch on the other side of the road, too, and I think some people could be too far on the "alarmist" side which brings its own damage. Requirements like "0 cases for 14 days in county" are completely unrealistic and impossible -- looking at our PolicyLab county-level modeling this would never be met in any county this whole year and possibly next year as well. To keep from going off to that alarmist ditch, we need to realize this is a "leaky bucket" virus that is all over the world so will be with us for a while. We can't expect 0 risk, but we can and should try to keep its spread under control and prevent surges that overwhelm hospital systems and lead to preventable deaths. And delaying school starting in surging areas may be necessary to keep the surge from worsening or continuing on too long.


But in areas where the viral levels are lower, it might be reasonable to try to open schools, but with careful precautions are previously noted. But I am worried about our ability to manage realistic expectations in this process given our fragile psyches regarding this crisis -- the moment a few infections pop up in a school (which is unavoidable BTW), some will want to immediately shut down the school even though that might not be warranted. The key is to manage it, not eliminate all risk, and to me it seems a realistic goal is to get it such that it is no more prevalent than other endemic viruses like common cold and flu, i.e. that we have safeguards in place to reduce the infection transmission rate to keep it from surging out of control, and isolate those infected and with those with symptoms and be sure to remove any unintended incentives to come to school when feeling sick. And schools need to have backup plans to further reduce capacity with an adapted hybrid plan or go to online learning if a serious outbreak emerges.


This is the hardest decision I've ever seen schools have to make, and also the hardest decision in this pandemic. There are huge ditches on both sides of the road so it is so hard to know exactly how to best handle this.





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7 Comments


Jeffrey Morris
Jeffrey Morris
Jul 30, 2020

Js: Houston has to be careful. I donated to No kids hungry a great charity focusing on those kids you mentioned. False positives rare except sometimes after recovering because it finds dead RNA and registers positive. False negatives common in asymptomatic infected and first few days of mild symptoms which is why they recommend waiting until a few days after symptoms start. But some people just don’t catch it even when exposed not sure why

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This is a really useful post. My question is tangential. Do we really believe that Israel had 10 new cases a day when it opened schools? I imagine the real number was 10x for that kind of rapid spread if we're to believe that people stop infecting others after 10 days.

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Jeffrey Morris
Jeffrey Morris
Jul 30, 2020

I think the key is that we have to tread lightly because we really don’t know how much viral load in a community schools can handle without surging. Rural counties with low viral levels have the best chance

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Lily Maria
Lily Maria
Jul 30, 2020

Thank you for your reply, Jeff! The Georgia Tech resource is very helpful - there seems to be a high correlation with covid and population density combined with popularity of the travel destination. I know the US schools have not opened during surges due to our school calendar's summer schedule, but can't we compared with countries like Sweden, Belgium, Japan, and Uruguay to at least less populated towns in the US that have lower cases? Also, from what I read, the daycares that stayed open, especially those serving our essential heathcare families (that were more likely to be exposed to covid), don't seem to have any increased covid spread. I would think that toddler aged children would be more likely…

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Jeffrey Morris
Jeffrey Morris
Jul 30, 2020

Lily: I totally agree -- the disparity issue is tragic. Schools that have taken precautions have generally done well, but the key is that those places all had viral levels down to low levels before opening -- many places in USA are surging and the infection load in the community is much higher. Georgia Tech researchers have put up an app to compute probability of at least one infected person in group of size 10, 25, 50, ... for each county in the USA based on current infection rates. One of the worst is Miami-Dade, FL, for which a random group of 25 has 98% chance of at least one infected, and a random group of 10 has a 7…

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