US adults who previously had COVID-19 contracted the disease at more than five times the rate of those who were fully vaccinated, according to data published today in Morbidity and Mortality Weekly Report (MMWR).Rolling out vaccines during a pandemic is not easy, and people can get confused by evidence that shows COVID vaccines don't work perfectly, including a study yesterday showing that household spread with the Delta (B1617.2) variant still happens after vaccination, albeit not as readily in the unvaccinated and not leading to severe cases (see today's CIDRAP News story).Yet the body of evidence continues to grow that, despite their imperfections, COVID-19 vaccines continue to work very well, and today's study adds to that.