Most children positive for COVID-19 at the outbreak of day care in Omaha were symptomatic, reports the Department of Health
China’s Sinovac COVID-19 vaccine is 67% effective in preventing symptomatic infection – Report from Chile
A variant of South Africa could ‘break through’ Pfizer vaccine; antibody can reduce symptomatic infections: Coronavirus update for April 13, 2021
Pfizer Covid vaccine blocks 94% of asymptomatic infections and 97% of symptomatic cases in Israeli study
