• US surpasses 16 million Covid-19 cases
• LATEST: Vaccine hesitancy now 'biggest challenge' in Covid fight
원문출처 : https://www.cnn.com/2020/12/11/health/pfizer-vaccine-what-we-know/index.html
원문출처 : https://www.cnn.com/2020/12/11/health/pfizer-vaccine-what-we-know/index.html