The Centers for Disease Control and Prevention (CDC) said in a study released Wednesday that natural immunity from a previous infection granted stronger levels of protection against the Delta variant of COVID-19 than vaccination alone.
Before Delta became the dominant strain of the coronavirus, individuals who had natural immunity were experiencing higher case rates than individuals who were only vaccinated, the study found, but since Delta took hold, those with natural immunity caught COVID-19 less frequently than those who were only vaccinated.
The study examined four categories of people — unvaccinated and vaccinated who had survived a previous COVID-19 infection, and unvaccinated and vaccinated who had never been infected — in California and New York between May and November 2021. The highest case rates were among those who had neither been vaccinated nor previously infected. The most protection against infection and hospitalization was in those who had both been vaccinated and survived a previous infection of the virus.
The agency cautioned that the data only measured results against the Delta variant and that Omicron may present new challenges that alter the calculus of natural immunity versus vaccination.
Biden administration officials and some public health experts have repeatedly downplayed the effectiveness of natural immunity against COVID-19, but this study is only the latest of many to indicate recovery from prior infection can equal, if not surpass, that offered from vaccination alone. Most research has shown that for maximum protection against reinfection or severe illness, those who were previously infected should still get vaccinated.
Many legacy media outlets covered the study by downplaying the finding that natural immunity outperformed vaccines and emphasizing that a combination of both provided the best protection. Headlines from the New York Times, Associated Press, CNN, and others claimed that vaccination offers the “best” or “safest” protection according to the study.
In a press call Wednesday, the CDC’s Dr. Benjamin Silk, an epidemiologist that co-authored the study, did not elaborate on the increased protection natural immunity provides but repeated the administration’s verbiage that every American should get vaccinated.