Scientists from Dresden Technical University said they believe children may act as a “brake” on chains of infection.

Prof Reinhard Berner, the head of pediatric medicine at Dresden University Hospital and leader of the study, said the results suggested the virus does not spread easily in schools.

“It is rather the opposite,” Prof Berner told a press conference. “Children act more as a brake on infection. Not every infection that reaches them is passed on.”

The study tested 2,045 children and teachers at 13 schools — including some where there have been cases of the virus. But scientists found antibodies in just 12 of those who took part.