Prior infection with Covid-19 gave at least as much protection from a repeat bout of the coronavirus as vaccination during the rise of the delta variant, according to a U.S. government study.
Before delta arose last summer, vaccinated people with no previous cases were about half as likely to be diagnosed with Covid as unvaccinated people who’d had the disease earlier, according to a U.S. Centers for Disease Control and Prevention analysis of data from California and New York. After delta became dominant in late June and July, those with prior cases alone were better protected than those who’d only received vaccines, without an earlier infection.