Clinical trials of SARS-CoV-2 mRNA vaccines have documented remarkable efficacy for prevention of COVID-19. These results are supported by observational studies showing similar effectiveness in real-world settings. However, additional community-based studies are needed to determine how well the vaccines perform in a wider array of people and circumstances than the original randomized trials. In this talk, I discuss the design, analysis and results of a large observational study investigating the effectiveness of SARS-CoV-2 mRNA vaccines among patients from six healthcare systems in North Carolina.