Ever since coronavirus disease 2019 (COVID-19) first emerged with devastating ferocity, the emphasis has been on interrupting its spread until effective, safe and targeted antivirals and vaccines become available. The chief focus has been on non-pharmaceutical interventions (NPIs), including school closures, social distancing and shelter in place orders.
School closure – necessary or not?
Much controversy has surrounded the closure of educational institutions, in particular, because of the feared impact of sudden and profound isolation of school-age children from their schoolfellows. Some studies have failed to confirm these fears, showing, indeed, a beneficial effect from the increased time spent with family and less negative peer pressure.
However, the primary aspect remains the epidemiological ramifications of this policy. A recent study published online in the journal JAMA Network Open explores the difference in incidence of infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative virus of COVID-19, between lockdown and the reopening of schools in November.
The Israel experience
Israel was badly affected by the pandemic, but its schools reopened as usual after the summer vacation, on September 1, 2020. At that point, active spread of the virus was occurring, and the incidence of COVID-19 was among the highest in the world.
The current study used daily case data from the Israeli Ministry of Health, the number of diagnostic reverse transcriptase-polymerase chain reaction (RT PCR) tests for the virus, and the test positivity rate (TPR). This was used to estimate weekly incidence by age group, according to the number of tests.
The researchers compared the adjusted incidence rate ratios (IRR) and the TPR for the last week of August 2020, before schools reopened, with those of the first three weeks of September. They also compared the months of November and December 2020, with the last week of October 2020, similarly.
The data came from over 47,000 children between the ages of 0 and 9 years, over 100,000 between 10-19 years, 151,000 adults 20-39 years of age, and 103,000 aged 40-59 years. The oldest age group contained 63,000 adults of 60 years or over.
The data was based on infected individuals.
What are the findings?
The findings show that the IRR increased least in the youngest age group, as did the TPR, in both September and November-December 2020. The values of the adjusted IRRs varied between 1.1% to 3.2% in the different age groups, with the highest increase being in those aged 10-59 years.
The TPR for this period varied between a low of 0.77 in the youngest participants to a high of 1.5 (or 1.6) in those aged 10-59 years.
With the November-December period, the IRRs were lowest, at 1.34, in the 0-9 years age group. With the rest, it varied from 2.5 to 3, for the most part, except for the 10-19 year age group.
The TPR varied between 0.75 in the youngest children, to nearly 1 in the 10-19-year-olds, through 1.3 from 20-39 years, and 1.5 in the oldest patients.
Small increase among young children
The adjusted IRRs in children showed significantly lower rates of increase, indicating a slow increase in the number of new cases, in the period immediately after schools reopened. Relatively, the slope was higher with increasing age.
In fact, from a slope of 26 in the age group 10-19 years, it increased sharply to 66, 88, and 92, in the succeeding age groups, before declining to 64 in those aged 60 years or more.
What are the implications?
The very low increase in IRR and TPR in the youngest children during both periods of school reopening, as well as the very low slope of adjusted incidence, indicate that the rate of infection among 0-9-year-olds in school is very low. This agrees with earlier studies that show the very low rate of infection and even of viral transmission among and by very young and primary-school-aged children.
The study was an observational study, making causal inferences difficult. Moreover, there is not much difference in the IRRs and TPRs in pre-teens, adolescents and young adults, relative to those aged 20-59 years. In short, those aged 10-59 years show relative homogeneity in their rates of infection and test positivity.
If children aged 0-9 years are neither infected readily, nor play a major role in transmitting the virus to their peers at school, school closures for this age group appear meaningless. “Therefore, resuming school for this age group when lockdown was released appears to have been safe for them.”
The same cannot be stated with confidence for older children and adolescents or young adults. They would probably be better off with online instruction until the pandemic situation resolves and after proper protocols have been set up to minimize viral transmission among older students in schools.