As the Covid-19 vaccine rollout continues in the United States, with people ages 12 and older receiving their shots, vaccine makers are now preparing for a next possible phase: booster doses.
원문출처 : https://www.cnn.com/2021/05/22/health/covid-19-vaccine-boosters-explainer-wellness/index.html
원문출처 : https://www.cnn.com/2021/05/22/health/covid-19-vaccine-boosters-explainer-wellness/index.html