Covid-19: should we really close the schools?

Leopoldo Salmaso 01/04/2020
As the days and weeks go by, political leaders can no longer afford to question experts about when will it be possible to loosen the lockdown.

The small assaults on supermarkets “justified by hunger”1 and false notices of home visits “for demographic checks”2 are an alarm bell that must be reacted to immediately in order to avoid social unrest at a probably devastating scale and acceleration, something never before seen in even the most dystopian fantasy movies. Therefore political leaders should not ask “when,” but “how” they would be able to begin to loosen the grip, while minimizing the risks of a significant epidemic rebound, and they should ask now.
Ultimately, it is a matter of “adapting to” the natural course of the epidemic, reaching the normalization phase as quickly as possible, while being ready to counter the eventual and forseeable re-ignition of outbreaks with proportionate measures, up to an unlikely but still manageable “selective and/or intermittent home confinement”3.
Having coordinated, in Tanzania and Italy, epidemiological surveys with the demographic sampling methods recommended by WHO4 in poverty-stricken countries (those methods guarantee excellent reliability with very reasonable costs − not only in money but even more so in time and human resources), I propose to do the same for surveillance of the Covid-19 epidemic curve.
First of all, decisions on when to make specific tests for the detection of SARS-CoV-2 (for now just PCR on nasal swabs, to be later accompanied by antibody tests) must be disciplined and strictly uniform. Based on the experience accumulated in different Italian regions, as well as in countries such as South Korea, consensus can be quickly reached on a few fundamental guidelines, which I anticipate here with reasonable approximation and with the sole purpose of accelerating the debate and the achievement of the necessary consensus:
1. All health and health related professionals, who frequently come into contact with symptomatic patients, should be provided with PPE (Personal Protective Equipment) providing the highest level of safety, and should be checked weekly until the first epidemic peak is extinguished; then again in case of secondary outbreaks.
2. Patients with suspicious symptoms should be tested according to the applicable protocols. Their contacts should be placed in home quarantine, and tested only if symptomatic.
3. In principle, and only with justified exceptions, no other person should be tested, except in the context of the sample surveys referred to in the following point.
4. Monthly surveys should be carried out on strictly randomized samples to cover the entire national population, with appropriate sample weighings. Any survey on a regional or more local scale should be compatible with and complementary to the methodology adopted at national level. Population sampling can be usefully adapted from the EPI-WHO strategy.
Secondly, it is advisable to apply the Delphi5 method to evaluate the efficacy/cost ratio of the measures currently adopted for the containment of the first epidemic peak. This method should be performed as soon as possible, and then usefully repeated after each sample survey. To summarize these steps in a few words:
A small number of experts (virologists, sociologists, economists) are convened. They choose the most relevant variables and for each of them they assign a value from 1 to 5 (1 = minimum weight; 5 = maximum weight for the spread of the epidemic). The zero value is not allowed because the final score is calculated by multiplying the partial scores; however, 0, … values are allowed, when the score of one cell is so favorable as to attenuate the “heavy” score of other cells in the same row.
All this has a purely conventional value: the absolute values do not matter but only the relative ones, that is the RANK. In fact, in the end, as long as the criteria are clear and shared, the rank helps a lot in evaluating the RELATIVE WEIGHT of each variable. The extremes are easily identified (MINIMUM SCORE = measures that can be taken immediately, being inexpensive and not very risky; conversely, caution is required before unleashing the measures carrying high scores). The identification of the intermediate band is arbitrarily, but can be decided upon following the acquisition of further information, especially thanks to the surveys described below.
Table 1 has a pure illustrative function: in fact the “true” scores must be agreed by the group of experts. The colors green, yellow, red are also arbitrarily attributed, but offer an immediate idea of the relative risks entailed by each measure.
Note the following points:
– Everybody, including non-experts, might easily agree on the variable that carries the lesser risk of contagion (open places, people alone or at a distance, with or without masks), and on the most risky one (100 or more people socialising in closed places, without masks).
– The total scores for the variables in green are very low, so whether masks are used or not would be almost insignificant. If these scores were confirmed, the containment measures in the green area could be loosened very quickly.
– The evaluation of costs (social and economic) is purposely omitted here, but the more relevant ones are highlighted in red.
– The step of REOPENING THE SCHOOLS shows an anomalous behavior, which deserves a thorough discussion.
Why reopen the schools?
Let’s ignore here arguments that have been the subject of heated controversy (e.g. grandchildren who would “kill” their grandparents) or have been undeservedly ignored (e.g. non-monetarized social costs6 almost completely overlooked). Let’s stick to pure epidemiological considerations:
If we look at the score in the first column, table 1, “reopening the schools” entails the highest level of risk, equal to “100 or more people socialising in closed places, without masks”. The other scores are also similar, with one striking exception: the long-term effectiveness (column 2) with a score that, alone, moves this variable to the green area. Why? Essentially for two reasons:
First reason: despite the enormous media and commercial pressures, no expert in the world encourages the illusion that effective vaccines can be produced against viruses as variable as SARS-CoV-2, nor can they find curative drugs7.
Second reason: since an artificial vaccination cannot be carried out, natural vaccination can be supported, exactly by promoting the circulation of the virus among the population groups who do not develop a serious disease. In fact, to date worldwide there is not a single under-10 dead with a positive SARS-CoV-2 test, and the case-fatality rate in the 10-39 years age group is 2 per thousand.
REOPENING THE SCHOOLS would favor what has been happening on our planet for 3.7 billion years: the co-evolution towards an increasingly peaceful coexistence between guests and parasites9; this is what is done regularly in laboratories all over the world to obtain attenuated vaccines, starting with Pasteur (1886, Rabies vaccine) and coming through Sabin (1959, Polio vaccine). 
6 Including the vital need of any child to be protected from fear and anxiety (see the movie “Life is Beatiful” by Roberto Benigni)