A nurse conducts a PCR test on a resident of the Basque town of Elorrio during mass testing
A nurse conducts a PCR (polymerase chain reaction) swab test on a resident of the Basque town of Elorrio during mass testing, following an upsurge of coronavirus disease (COVID-19) cases in the municipality, in Elorrio, Spain March 23, 2021. REUTERS/Vincent West