Relatively early in the Covid-19 pandemic, in March, I made the case against closing schools and later warned that doing so, even though it may be necessary, will cause many children a lifetime of harm. I was expecting that by now, two months on, we would know whether such drastic steps were justified epidemiologically. But one of the most frustrating aspects of SARS-CoV-2 is that it just doesn’t want to yield that data easily. Nonetheless, policymakers all over the world must now weigh the different risks and come to a decision.

The right one is to get the kids back into their classrooms. And not just partially, as our schools are doing here in Berlin, where children rotate in and out of their physical classes in a complex and staggered pattern for specified hours or days, depending on their grade. Ask parents or children, or at least those who have access to online learning, and most will say that this stop-go education is more stressful and less effective than schooling was during the total lockdown.

On one side of the ledger, there’s the probable role children play in spreading the coronavirus in the wider population, and thus their contribution to renewed spikes in cases. On the other side is the damage school closures do to their education, well-being and life prospects, and indirectly even to the cohesion and prosperity of entire societies in the coming generation.

It’s pretty well established that healthy children — that is, those without preexisting conditions — are somewhat less likely to catch the coronavirus and a lot less likely to suffer severe symptoms. Recently reported cases of delayed whole-body inflammations resembling Kawasaki disease are scary, but very rare.

The relevant question for epidemiologists, therefore, is whether children, especially when asymptomatic, can easily spread the virus to adults, causing new outbreaks and endangering high-risk groups such as the elderly. With the seasonal flu, this is the case. With the coronavirus, the science just isn’t clear.

Data from several countries — notably Iceland — suggest that children are less likely to give the virus to their parents or other adults than to catch it from them. Other research counters that children may be just as contagious as adults.

Perhaps the most controversial such study was done by a team around Christian Drosten, a virologist here in Berlin who’s become a national celebrity since the outbreak. They published a paper showing that the viral load in children is similar to that in adults. Drosten concluded that children are infectious enough to warrant keeping schools closed.

But other scientists, including statisticians, have questioned the Drosten team’s math. Drosten now plans to update his study with more detailed data. As a sign of just how charged the controversy has become, this week he received a package containing a vial filled with an apparently dangerous liquid and the instruction, “drink this – it’ll make you immune.” Meanwhile, several German pediatric associations have concluded that children are indeed significantly less contagious, and that schools should be opened.

As this debate rages on, what about the other side of the ledger, the damage done not by Covid-19 but by interrupted education? Here there’s really no controversy. This recent report signed by more than 90 education experts and economists — again, here in Germany, but they could be anywhere — spells it out.

As schools stay totally or partially closed, the experts argue, children aren’t merely learning less, they’re also forgetting much of what they’d already learned, from grammar to social skills. The worst off, unsurprisingly, are kids from low-income or dysfunctional families, not to mention those who suffered abuse or stress at home even before the pandemic. For these youngsters, school closures mean the disappearance of healthy meals, safe surroundings and oases of support.

The consequences will last, both for the children and for their societies. Many of the kids will spend less time in school or university even in later years, the report’s authors say, and will achieve less while they’re there. They’ll be more likely to be unemployed as adults. And even when they do work, they will earn less. Each year of school closures costs people between 7% and 10% of foregone lifetime income, so even a few months can make a big difference. These cohorts of the undereducated will strain welfare systems and public budgets, dampen the economic growth of entire countries and increase inequality enough to stress political cohesion.

In countries or regions where Covid-19 is more or less under control — spreading, but not overwhelming health systems — the responsible policy is therefore to open schools. It will lead to some additional infections and fatalities. But the alternative would lead to even more suffering, including death, down the line.

As a parent, I know the kids won’t wear their masks properly and don’t always count out the whole Happy Birthday song while washing their hands. But let’s teach them how to stay as safe as they can. Above all, let’s teach them again.

© 2020 Bloomberg