At more than 5 months, the mRNA-1273 vaccine continues to be efficacious for preventing COVID-19 and severe COVID-19, according to a study published in the New England Journal of Medicine. Investigators enrolled volunteers at high risk for COVID-19 or its complications and randomly assigned them to receive two intramuscular injections of mRNA-1273 or placebo, 28 days apart, at 99 centers. Median follow-up was 5.3 months in the blinded phase. Vaccine efficacy was 93.2% for preventing COVID-19 illness and 98.2% for preventing severe disease. The efficacy was 63.0% for preventing asymptomatic infection starting 14 days after the second injection. Across ethnic and racial groups, age groups, and participants with coexisting conditions, the investigators found vaccine efficacy to be consistent.