Increased Risk of Adverse Events After COVID-19 Vaccination Among Naturally Immune: Study

A nurse prepares to administer the Pfizer-BioNTech COVID-19 vaccine at Guy's Hospital in London on Dec. 8, 2020. (Frank Augstein/Pool via Reuters)

People who have recovered from COVID-19 have a higher risk of adverse events after vaccination, according to a new study.

Health care workers who had post-infection immunity reported more adverse events after receipt of Pfizer’s COVID-19 vaccine than those without natural immunity, researchers in England said.

Rachael Raw of Newcastle University’s School of Medicine and Health and her co-authors said the study revealed a “significant association” between natural immunity and one or more moderate/severe adverse events after doses one, two, and three of Pfizer’s vaccine.

Moderate/severe adverse events include diarrhea, fatigue, and fever.

Dr. Jeffrey Klausner, a clinical professor of medicine at the University of Southern California Keck School of Medicine, said he found the reported adverse events “trivial.”

“The type of adverse events that they report are trivial, and I would not call those adverse events but expected side effects like fever, headache achiness, which are very common after vaccination. Fortunately, those side effects last no more than 12 or 24 hours and are easily treatable with Tylenol,” Klausner, a former U.S. Centers for Disease Control and Prevention medical officer, who wasn’t involved in the research, told The Epoch Times via email.

“The study has no clinical or public health significance and is not surprising. The study verifies that people’s immune systems are working as expected.”

Dr. Peter McCullough, chief scientific officer of The Wellness Company, disagreed.

“This study, among others, confirms that COVID-19 recovered patients should have never have accepted vaccination,” McCullough, who also wasn’t involved in the research, told The Epoch Times in an email.

More on Research

The UK researchers analyzed surveys completed by health care workers who work at hospitals in northeast England for the retrospective, observational study.

Workers reported when they received a Pfizer COVID-19 vaccine booster dose and an influenza vaccine dose.

One of the aims was to find out whether concomitant influenza and COVID-19 vaccination enhanced adverse events. Researchers also analyzed whether prior COVID-19 infection led to worse adverse events.

About a third of the 534 workers who responded had recovered from COVID-19, and 92 percent received an influenza vaccine in addition to a Pfizer booster, which comes after a primary series because the vaccines have performed worse and worse against newer COVID-19 variants.

Those with prior COVID-19 were more likely to report experiencing one or more of almost all of the adverse events listed, including pain, swelling, fever, headache, and stiff joints. Nausea and vomiting was the only adverse event more common among those with prior COVID-19.

While, overall, the frequency of adverse events was reduced compared with after doses one and two, the study results show “the effect of prior COVID-19 on vaccine-associated AEs [adverse events], was again carried over to the third/booster BNT162b2/Pfizer dose in terms of increased AEs,” the researchers said.

They also found no signs of more adverse events or worse adverse events among workers who received an influenza vaccine within seven days of a COVID-19 booster.

The study was published by PLOS Global Public Health.

Pfizer didn’t respond to a request for comment.

Previous Research

Previous studies have found a higher risk of adverse events among the naturally immune, who many papers have found are better protected against COVID-19 than the vaccinated.

Raw and other UK researchers have contributed to two of these studies.

In 2021, they found that previous infection was associated with increased adverse events following Pfizer vaccination. Workers with natural immunity also reported to the researchers that adverse events were worse after the first dose but not the second.

Other researchers have found “significantly higher” reactogenicity in people who recovered from COVID-19 and an increased risk of side effects for both the Pfizer and Moderna vaccines among the naturally immune.

The higher risk is likely driven by how the immune systems of the recovered are already primed to protect against COVID-19, according to Raw and her co-authors.

Other papers, including a recent U.S. study, have stated that natural immunity is superior to vaccination, although both wane significantly over time against reinfection and more slowly against severe illness.

Some experts advocate for so-called hybrid immunity, or vaccination despite natural immunity, because some research has found that it bolsters protection. Others note that some research shows little added protection and point to the higher risk of adverse events as reasons to not vaccinate the naturally immune.