The prognosis for school reopenings

A model shows that a rise in cases in children could occur, but in-person schooling can proceed with caution

Updated - December 04, 2021 10:29 pm IST

Published - September 02, 2021 12:02 am IST

New Delhi: Students attend their class at a Sarvodaya Bal Vidyalaya which reopened after further ease in COVID-19 restrictions, in New Delhi, Wednesday, Sep 1, 2021. (PTI Photo/Vijay Verma)(PTI09_01_2021_000030B)

New Delhi: Students attend their class at a Sarvodaya Bal Vidyalaya which reopened after further ease in COVID-19 restrictions, in New Delhi, Wednesday, Sep 1, 2021. (PTI Photo/Vijay Verma)(PTI09_01_2021_000030B)

Schools began opening in a phased manner across several Indian States on September 1. These include the States of Delhi and Uttar Pradesh. Schools for senior students have already been open for the past few weeks in a few States.

Debates around when to open schools in the midst of a COVID-19 pandemic have been divisive, and not just in India. These have focused on the balance between minimising the risk of disease for children and their family members, and maximising in-person schooling. The arguments have largely reflected the biases of those with strongly held points of view on both sides.

Editorial | Learning safely: On schools reopening

Mathematical models

With schools opening across India, will we observe an increase in cases in school children? Could this lead to another peak in overall cases as children bring infections back home? We addressed these questions using a mathematical model, presenting our findings (the meeting was in-camera) to an expert group of the World Health Organization this week.

How did our model address this question? Our model describes schools embedded within communities, that comprised families of different sizes. If schools are open, children move between their homes and schools. Children stay at home if schools are closed. Adults go to work at assigned workplaces or stay at home. The distribution of ages in the community is based on the age structure of the population in a typical mid-sized Indian city.

We describe the spread of COVID-19 from person to person, accounting for reductions in this rate from non-pharmaceutical interventions including masking. We account for a level of prior infection in the community, as measured by serological surveys that look for antibodies for COVID-19. Our model accounts for the possibilities of asymptomatic, mild and severe disease, as well as hospitalisations and deaths. These vary across different age groups. We allow two doses of vaccinations, separated by 90 days, as well as the possibility of breakthrough infections, where the immunity granted by vaccines is breached. We incorporate what is currently known about the protection provided by vaccines against mild and severe disease. Our model reflects the current state of the epidemic in India at the moment. We start with children at home and then study how cases spread in children and in adults when schools open.


Findings of the model

Based on our model, an increase in cases in children is expected as schools are opened, relative to keeping them closed. However, this does not lead to a new wave under the current epidemic conditions in India. Specifically, in regions with the levels of seroprevalence expected across much of north India, we expect this increase in cases to be marginal. Children are at lower risk of severe disease associated with COVID-19 — very few of these infections are likely to lead to complications.

We can further restrict any increase in infections among children by ramping up immunisation in older age groups and by continuing non-pharmaceutical interventions, including requiring face masks, improving ventilation, shifting more activities to outdoor venues, and increasing the number of students attending school slowly over a period of several weeks. Such interventions should be continued until we achieve an overall seroprevalence of 75%-80%, adding numbers from recent infections and from vaccinations. Beyond this point, we find that these measures make little difference. We found that opening schools was not likely to contribute to an increase in cases among older individuals.


A typical Indian community considering whether to open schools should be on the downswing of the pandemic or past it in terms of having sufficient numbers of those who are — at least for the time being — relatively immune to the disease since they have been recently infected. Roughly speaking, this corresponds to about 45% seropositivity to begin, in the absence of vaccinations. Adding vaccinations on top of that cushions any sharp rise in cases, especially if combined with COVID-19 non-pharmaceutical interventions.

Interpreting the results

Much of India has encountered COVID-19, particularly the Delta variant. Some have been reinfected by it. Seropositivity levels in children are comparable to those in adults — keeping children at home has not served the purpose of keeping them from becoming infected. This is a point whose importance has been insufficiently stressed: if children are as likely to pick up an infection from the community while staying at home, there is little reason to keep them out of school.

More than 60% of the vulnerable population have been given one dose of vaccine; in some cases, two doses. There is a case for prioritising the vaccination of family members, especially elderly ones, of school-going children as well as of teachers and other school staff. We see the advantages of this in our model simulations.


We stress that a rise in cases could occur once schools are opened. Indeed, children who show symptoms after testing positive should be screened for potentially more severe versions of the disease. However, the number of severe cases in children is very small since children are better protected against disease than adults.

With COVID-19 and schools, the trade-off is between the long-term consequences of disruptions in learning and socialisation in children and the short-term possibility of their contracting an infection. Finding the right balance between these two factors is crucial. Given the state of the Indian epidemic as well as the likely possibility that COVID-19 will transition into endemicity, there seems to be little reason to continue to have schools closed. This should be true especially in States and communities where seropositivity is in excess of 80%.

State-specific approach

For low seropositivity States such as Kerala and Maharashtra, a better understanding of the current fraction of the population that has antibodies, either from prior infection or from vaccination, would help. Once this crosses the 80% level, we see no reason why they should not also reopen. It remains important to continue studying the spread of COVID-19 over the next six months to understand how quickly immunity due to prior infection wanes over time.


Actions called for

Our simulations do not include testing and tracing, although this is one way of keeping any increase in cases in check; nor does it include the possibility of new variants. The possibility of random testing of schoolchildren at regular intervals has been raised. We favour, instead, local decisions to close schools if test positivity in the community exceeds a preset bound, since children seem to be acquiring the infection in their communities at the same rate at which adults acquire them.

While models are imperfect guides to the future, especially because they must make assumptions about human and virus behaviour, they often provide useful intuition. Comparisons to other countries are not particularly helpful, since each country’s situation with respect to the disease is different. The recent uptick in vaccination numbers is encouraging and should hopefully be sustained in the coming weeks. This will help in ensuring that children can return to school. For this, we need not wait until vaccines for children are available.

Brian Wahl is an Assistant Scientist at the Johns Hopkins Bloomberg School of Public Health, U.S. Sandeep Krishna is an Associate Professor at the Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Bengaluru. Gautam I. Menon is a Professor at Ashoka University, Sonepat and at the Institute of Mathematical Sciences, Chennai. The views expressed here are personal

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