Can people with asymptomatic or pre-symptomatic COVID-19 infect others: a systematic review of primary data

Abstract

AbstractAsymptomatic but infectious people have been reported in many infectious diseases. Asymptomatic and pre-symptomatic carriers would be a hidden reservoir of COVID-19.AimThis review identifies primary empirical evidence about the ability of asymptomatic carriers to infect others with COVID-19 pandemic and reflects on the implications for control measures.MethodsA systematic review is followed by a narrative report and commentary inclusion criteria were: studies reporting primary data on asymptomatic or pre-symptomatic patients, who were considered to have passed on COVID-19 infection; and published in indexed journals or in peer review between January 1 and March 31, 2020.ResultsNine articles reported on 83 asymptomatic or pre-symptomatic persons.ConclusionsThe evidence confirms COVID-19 transmission from people who were asymptomatic at the time. A series of implications for health service response are laid out.