The war against Covid-19 is still in its early days. Some expect that vaccinations will bring life back to normal within a year, but this is the most optimistic scenario with many assumptions. On the other hand, we now have a better understanding of Covid-19. In the early days of the crisis, we did not know much about the virus. Social distancing guidelines were set to minimise its spread and schools were closed. But now, we should reopen schools. Closing schools should be the last option. This is because school closures do not help prevent the spread of Covid-19 and damage students and society . First, closing schools appears to have no effect. In Australia and Germany, researchers found little change in Covid-19 outbreaks before and after schools were reopened. In South Korea, only three out of 127 confirmed student cases aged 3 to 18 were infected at school after they had reopened. Most were infected at home, in restaurants or multipurpose facilities. In rural Wisconsin, US, seven out of 191 students were infected in schools during the 13-week face-to-face school period last autumn. Why are school closures unhelpful? Students not going to school does not mean they stay at home. If they meet friends outside school, closure is meaningless. Second, the loss of class time causes irreparable damage to children. Our children are losing the positive effects of education. Education can increase wages, lower the likelihood of smoking and increase longevity. It can help develop integrity, openness and emotional maturity, and its effects can translate into the next generation. Education has a profound impact on our lives. Some might think online education can replace regular school classes. However, many adults struggle to concentrate for more than a couple of hours online. Students who do not have a guardian at home during the day are almost neglected. Furthermore, online education has a limited effect in the development of non-cognitive skills. School restrictions leave children vulnerable to other risks. According to a Save the Children survey of 8,000 children and 17,000 parents from 37 countries, the number of abused children increased from 8 per cent to 17 per cent as time at home increased. Third, school restrictions can intensify inequality . The negative effects of school restrictions are concentrated among those with low socio-economic status. For low-income families, online classes might not be fully available because of a lack of Wi-Fi connections and tablet computers. It is also difficult for them to catch up academically through private education. Fourth, children appear less likely to be infected by Covid-19. In addition, most infected children have mild or no symptoms, except for a few with serious underlying conditions. Fifth, school restrictions can put grandparents at risk, given the possibility of increased contact with children whose parents need them for child care. This puts the elderly relatives, who are among the most vulnerable to the virus, at greater risk of infection. Most Covid-19 infections in US schools have occurred among high school students and during athletic competitions. So, during physical activities, students should wear a mask to enhance safety. Limits should also be placed on the number of students sitting together during lunch, when masks must be removed. Hong Kong’s Education Bureau recently announced that face-to-face classes could increase to one-third of pupils after the Lunar New Year. This is a step in the right direction, but a third is still not enough considering the harm done by school restrictions. The bureau also introduced a programme where schools can fully resume half-day, face-to-face classes if all staff are regularly tested for Covid-19 . The government should take full responsibility to make this possible in all schools, and provide students with full-day options. Once in-person classes resume, there will inevitably be Covid-19 cases in schools. Would attendance again be restricted, to decrease overall infections? As we reduce infections in schools, more occur in other places children visit. We are also paying the price of school closures – which affect our children’s future, reduce life expectancy and put grandparents at risk. The Hong Kong government should not underestimate the seriousness of school closures. Such restrictions cause invisible but serious damage to students and society. In the first half of 2021, the expansion of regular face-to-face classes should be a priority. Hyuncheol Bryant Kim is an associate professor in the Economics Department at Hong Kong University of Science and Technology. He received an MD from Yonsei University, Korea, MPH from Seoul National University, Korea, and PhD in economics from Columbia University, US