FIA doctor Professor Gerard Saillant says he is "surprised" that so few cases of coronavirus have been detected since the 2020 'corona calendar' kicked off last month.
Thousands of tests have been carried out since the racing began in Austria and then moved on to Hungary and Britain.
But so far, only two employees of a cleaning company in Hungary and Racing Point driver Sergio Perez have tested positive.
FIA president Jean Todt says the protocols set up to deal with the infections worked well, especially in Perez's case.
"The two people who were with him were immediately quarantined," he told AFP France. "The other three were checked and then were allowed to work, albeit at the factory."
Perez was replaced at Silverstone by Nico Hulkenberg, and Todt says he personally signed the former Renault driver's super licence.
Some have criticised the strict measures against the virus, but the head of the FIA's medical commission says he is positively surprised.
"What surprised me is that there have not been more cases," said Professor Saillant.
"That there were three cases out of 12 000 tests strikes me as remarkable," he added.