News Moderna study suggests 3rd dose effective vs. omicron; Trump booed when he says he got booster: COVID-19 updates December 20, 2021John Bacon, Karen Weintraub and Celina Tebor, USA TODAYComments Off on Moderna study suggests 3rd dose effective vs. omicron; Trump booed when he says he got booster: COVID-19 updates A study suggests Moderna's booster shot is effective against omicron. New COVID infections up 41% from a month ago. Latest news.