Protection from prior COVID-19 infection was better than the protection from COVID-19 vaccines against the Delta virus variant, according to a new study published by the Centers for Disease Control and Prevention (CDC).
Researchers analyzed health records from California and New York that were entered between May 30 and Nov. 20, 2021. They separated COVID-19 patients into four groups: unvaccinated with no previous COVID-19 diagnosis, unvaccinated with a previous COVID-19 infection, vaccinated with no prior COVID-19 infection, and vaccinated with prior COVID-19 infection.
Those who had not received a COVID-19 vaccine but were infected previously with the illness were much less likely to test positive for COVID-19 when compared to vaccinated people who had not gotten COVID-19, according to the study, which was published Wednesday in the CDC’s Morbidity and Mortality Weekly Report.
People who had not gotten a vaccine but did have a prior infection, also known as natural immunity, were also less likely to land in a hospital than the vaccinated without natural immunity, according to hospitalization records from California.
The unvaccinated without prior infection were by far the most likely to contract COVID-19 and require hospital care, the study found.
“These results suggest that vaccination protects against COVID-19 and related hospitalization and that surviving a previous infection protects against a reinfection. Importantly, infection-derived protection was greater after the highly transmissible Delta variant became predominant, coinciding with early declining of vaccine-induced immunity in many persons,” researchers, including Tomás Leon with the California Department of Public Health, wrote.
Because the time period studied only went through late November, more research is needed to examine whether vaccination and prior infection protects as well against the Omicron virus variant, which became dominant in the United States last month, the researchers said.
They also encouraged people to get vaccinated even if they have natural immunity, pointing to the finding that the vaccinated with prior infection were the most protected against infection and hospitalization, according to the health records.
Experts are divided as to whether the naturally immune should get a jab, with some noting studies that indicate the protection increases but others highlighting how the elevation is, in many cases, minimal, and pointing to other research that suggests side effects are more likely among naturally immune getting a vaccine.
Limitations of the report include the potential for bias related to unmeasured confounding and the analysis not including information on the severity of infection.
Dr. Jeffrey Klausner, a clinical professor of medicine at the Keck School of Medicine of the University of Southern California who was not involved in the study, told The Epoch Times in an email that the findings “strongly support the need to update our vaccination policy, work and school requirements,” with those who can demonstrate they have natural immunity being given equal access as those who are vaccinated.
“Vaccination is a much, much, safer pathway to immunity than getting infected, but in an otherwise healthy person who has recovered, they should have confidence that they [have] protection against severe disease, hospitalization, and death,” he added.
The Morbidity and Mortality Weekly Report is a weekly publication from the CDC. Most studies are not peer-reviewed but the articles are reviewed by CDC officials before being published and the content, by the time it’s published, “constitutes the official voice” of the CDC, the agency has said (pdf).
