哈佛近期关于新冠的3篇报道
1. Harvard epidemiologist shares early impression of variant as first U.S. case is identified in California
2. Vaccine reduces transmission in breakthrough cases
3. Moderna edges out Pfizer vaccine in head-to-head comparison
https://news.harvard.edu/gazette/story/2021/12/moderna-vaccine-slightly-more-effective-than-pfizer/