On the effect of age on the transmission of SARS-CoV-2 in households, schools and the community

Goldstein, E; Lipsitch, M; Cevik, M

There is limited information on the effect of age on the transmission of SARS-CoV-2 infection in different settings. We undertook a review of published data/studies on detection of SARS-CoV-2 infection in contacts of COVID-19 cases, as well as serological studies, and studies of infections in the school setting to examine those issues. Those sources suggest significantly lower susceptibility to infection for children aged under 10 years compared to adults, for elevated susceptibility to infection in adults aged over 60y, and for the risk of SARS-CoV-2 infection associated with sleeping close to an infected individual. Those sources also suggest that younger adults (particularly those aged under 35y) often have high rates of SARS-CoV-2 infection in the community. Additionally, there is evidence of robust spread of SARS-CoV-2 in high schools, and more limited spread in primary schools. Some countries with relatively large class sizes in primary schools (e.g. Chile and Israel) reported sizeable outbreaks in some of those schools, though the amount of transmission occurring in these schools (vs. outside) is not clear from current reports. Nonetheless, these reports suggest that classroom crowding and other factors related to social distancing in classrooms/schools may play a role in the spread of SARS-CoV-2 in primary schools. Those findings should have implications for school openings in different age groups of children, and they suggest the need to better protect adults over the age of 60 during the community spread of SARS-CoV-2.