Children with the new coronavirus may be as infectious as adults, according to a study from Germany that recommends caution against an unlimited reopening of schools and kindergartens.

While children have a lower risk of developing severe illness from Covid-19, they may be no less capable of spreading it. Levels of virus in the respiratory tract — the main route via which the pathogen is transmitted — don’t appear significantly different across age groups, Christian Drosten, director of the Institute of Virology at Berlin’s Charite hospital, and colleagues found.

Children contract the coronavirus less often and with less severity, and there don’t appear to be cases of a child passing Covid-19 to an adult — observations that may be “misunderstood as an indication of children being less infectious,” Drosten and colleagues said.