It takes just a tiny virus-laden droplet -- about the width of a human blood cell -- to infect someone with Covid-19.
원문출처 : https://www.cnn.com/2022/03/31/health/first-challenge-study-covid-19/index.html
원문출처 : https://www.cnn.com/2022/03/31/health/first-challenge-study-covid-19/index.html