Nation Moderna study suggests booster is effective against omicron; new infections up 41% from a month ago: COVID-19 updates December 20, 2021 Celina Tebor, Karen Weintraub and John Bacon, USA TODAY Comments Off on Moderna study suggests booster is effective against omicron; new infections up 41% from a month ago: 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.