Another study suggests that a third vaccine dose is necessary to protect populations against the omicron variant.

Clinical severity of, and effectiveness of mRNA vaccines against, covid-19 from omicron, delta, and alpha SARS-CoV-2 variants in the United States: prospective observational study – The BMJ

News Release: Third vaccine dose critical for protecting populations against omicron variant – BMJ Newsroom

Commentary on Twitter

mRNA vaccines are highly effective in preventing covid-19 associated hospital admissions related to the alpha, delta, and omicron variants. But three doses are needed to achieve a similar level of protection against omicron, finds a large US study: https://t.co/YMm176gmby

— The BMJ (@bmj_latest) March 10, 2022