A study published in JAMA Network investigates the association between receving one dose of the Moderna (mRNA-1273) vaccine and SARS-CoV-2 infection. The study finds that the first dose was 78% effective at preventing new cases one week after receiving the vaccine, and around 95% of new infections were prevented two weeks after inocculation of the first dose. The analysis was performed among healthcare workers who were not vaccinated prior to the study.