Another exciting Monday morning for COVID-19 vaccines! Moderna is reporting 94.5% efficacy for their mRNA vaccine.

Read on for a biostatistician's breakdown of the interim results. 10 tweets on severe disease, subgroup analysis, and more.

Press release: https://investors.modernatx.com/news-releases/news-release-details/modernas-covid-19-vaccine-candidate-meets-its-primary-efficacy

Of course, I'll start with the topline result of 94.5% efficacy (90 placebo cases, 5 vaccinated cases). For a high efficacy vaccine, 95 cases is a lot of data. In event-driven trials, the number of cases matters more than the number of participants. 2/10 https://twitter.com/nataliexdean/status/1325820514816974849?s=20

Both Pfizer and Moderna's vaccines are mRNA-based. Thus, it's reasonable that results are similar. Still great to see! This is exciting because mRNA vaccines are designed for pandemics but were previously unproven. Adding a new tool to our toolbox! 3/10 https://twitter.com/nataliexdean/status/1325820512946302977?s=20

A particular strength of this early result is that it showed a very favorable split for the prevention of severe disease. All 11 were in the placebo arm. No results were provided on this analysis for Pfizer, so we were left unsure about the level of evidence. 4/10