Transient infection with SARS-CoV-2 without induction of systemic immunity

SARS-CoV-2 testing using PCR is currently used as screening test to guide isolation and contact tracing. Among 1,700 players and staff of the German Bundesliga and Bundesliga 2 who were regularly tested twice weekly, 98 individuals had a positive PCR. Among those, 11 asymptomatic cases were identified who only had a transient single positive PCR of low viral load. As only one out of 11 individuals developed SARS-CoV-2 specific cellular and humoral immunity, this indicates that transient colonization with SARS-CoV-2 may frequently occur without systemic induction of specific adaptive immunity. This knowledge may have implications for management of isolation and contact tracing, which may not be justified in these cases.