Coronavirus re-infections raise concerns about immunity
That has fueled fears about the effectiveness of potential vaccines against the virus, which has killed hundreds of thousands of people.
Health workers wearing protective gear are seen at a mobile testing station for miners of the Bielszowice coal mine, following the coronavirus disease (COVID-19) outbreak in Ruda Slaska, Poland July 27, 2020.(photo credit: REUTERS)ByREUTERS
