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Andy Nguyen
By Andy Nguyen January 26, 2022

Blog post ignores important context about COVID-19 immunity study

If Your Time is short

  • A CDC study on the spread of the delta variant found that unvaccinated people who were previously infected with COVID-19 accounted for fewer cases than fully vaccinated people who had never been infected.
  • However, the study was conducted before the spread of the more infectious omicron variant and before booster doses were widely offered to the public.
  • The CDC study said vaccination is the best form of protection against the virus, even for people who previously had COVID-19.

A blog post claims that according to a study, people who are unvaccinated and previously infected with COVID-19 have better protection against the coronavirus than some fully vaccinated people.

"BOMBSHELL: The CDC admits that natural immunity from prior infections is superior to vaccinated immunity alone," the Jan. 19 post claims, citing a study from the federal health agency Centers for Disease Control and Prevention.

The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

The blog post gives the impression that COVID-19 vaccination is not helpful for people who have had the virus, and that previously infected people will be able to avoid hospitalization and death if they get COVID-19 again. But that ignores the limited scope of the study and dismisses the conclusion made by researchers — that vaccination can help prevent serious illness, hospitalization and death. 

A previous COVID-19 infection does not guarantee that a person will not need medical care if they get the virus again.

CDC study

The blog post cites a CDC study that looked at how people fared against the COVID-19 delta variant between May and November 2021. The delta variant was first reported in India before making its way to the United States in March 2021, according to the CDC.

Researchers looked at infection and hospitalization rates among four groups of people in New York and California:

  • Vaccinated people who had previously been infected with the virus
  • Vaccinated people who had not previously been infected
  • Unvaccinated people who had previously been infected
  • Unvaccinated people who had not previously been infected

Researchers found that people who had a natural immunity from a previous COVID-19 infection were better protected against the virus during the delta-fueled surge than vaccinated people who had never been infected.

But the CDC offered several caveats about its analysis. 

The CDC said it completed its study before the extensive spread of the more infectious omicron variant, "for which vaccine or infection-derived immunity might be diminished." The study also happened when most people didn’t have access to a booster dose of the COVID-19 vaccine, which would provide additional protection against the virus.

The study also had a limited sample size and did not include information about the severity of previous infections or factor in deaths from the virus. 

COVID-19 vaccination remains important

The CDC study’s main takeaway "clearly shows" that vaccination is the safest form of protection against COVID-19, and it provides additional protection for people who have already been infected, Dr. Erica Pan, state epidemiologist for the California Department of Public Health, told PolitiFact.

"It shows that people who remain unvaccinated are at the greatest risk of hospitalization and death," she said. "Outside of this (CDC) study, recent data on the highly contagious omicron variant shows that getting a booster provides significant additional protection against infection, hospitalization and death."

Another CDC report, from October 2021, affirmed that people who have been infected with the virus should still get vaccinated. Vaccinations coupled with a prior infection provide stronger protections against severe disease, hospitalization and death related to the virus than natural immunity alone. 

A study from the Mayo Clinic found that unvaccinated people who have previously been infected are twice as likely to get the virus again as those who are fully vaccinated. Meanwhile, a Johns Hopkins Medicine study shows that a fully vaccinated person who has been previously infected will have higher levels of antibodies that can help stave off another COVID-19 infection than an unvaccinated person who has had the virus.

Our ruling

A blog post claims, "the CDC admits that natural immunity from prior infections is superior to vaccinated immunity alone." 

The post is misleading and omits key details. 

CDC researchers found that during the COVID-19 surge driven by the delta variant, unvaccinated people who had already had the virus were less likely to get COVID-19 than fully vaccinated people who never had the disease. However, the study concluded that unvaccinated people are still at a high risk of reinfection and that the best defense against the virus remains being fully vaccinated. 

The study was done prior to the surge from the omicron variant and before COVID-19 vaccine booster shots became widely available. 

The statement contains an element of truth but ignores critical facts that would give a different impression. We rate it Mostly False.

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Blog post ignores important context about COVID-19 immunity study

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