By Megan Redshaw
People who have moderate to severe COVID-19 prior to vaccination may have increased reactogenicity to COVID-19 vaccines, according to a Canadian study.
Individuals previously infected with SARS-CoV-2 develop immunity and may be more likely to experience adverse events following COVID-19 vaccination compared to those with no history of infection, according to a study published in Clinical Infectious Diseases.
Canadian researchers conducted a large, prospective observational study to assess the short-term safety of COVID-19 vaccines in adults with a previous history of SARS-CoV-2 infection.
Study participants were sent an electronic questionnaire seven days after receiving their first, second, and third vaccine doses to assess whether adverse events experienced after vaccination prevented daily activities, attendance at work or school, or required medical care, including hospitalization.
Among 684,998 vaccinated participants included in the analysis, 369,406 received Pfizer’s COVID-19 vaccine, 201,314 received Moderna, and 113,127 received AstraZeneca’s viral vector vaccine.
There were 18,127 individuals (2.6 percent) who reported previous laboratory-confirmed COVID-19 infection two to six months before receiving their first vaccine dose.
According to the study, individuals previously infected with SARS-CoV-2 were more likely to experience an adverse event the week following vaccination—regardless of the vaccine type—that interfered with daily activities, school, and work or required emergency department visits or hospitalization.
After the second and third vaccine doses, the greater risk associated with previous SARS-CoV-2 infection was also present but was weakened compared with the first dose.
The association was lower or absent for all doses after mild or asymptomatic infection. In other words, the risk was most significant among those who experienced moderate to severe COVID-19 prior to vaccination.
In addition, mRNA COVID-19 vaccines continued to produce increased immune reactions in previously infected individuals, whereas AstraZeneca’s viral vector vaccine did not. Following Pfizer or Moderna’s booster—or third vaccine dose—researchers found that a higher proportion of previously infected participants reported adverse events that interfered with daily activities, school, or work—or that required medical intervention.
“The association is stronger after the first dose than after the second and third doses,” the authors wrote. “Providers should consider additional vaccine counseling on expected adverse effects for individuals previously infected with SARS-CoV-2 prior to vaccination,” they concluded.
“These findings are not surprising, nor should any immunologist be surprised,” public health advocate and immunologist Dr. Hooman Noorchashm told The Epoch Times. “If you vaccinate people who’ve experienced natural infection, especially recently, you’re potentially opening the door to medical complications.”
Dr. Noochashm recounted the case of a young orthopedic surgeon, J. Barton Williams, who died on Feb. 8, 2021, from multi-system inflammatory syndrome (MIS) after receiving his second dose of Pfizer’s COVID-19 vaccine. MIS is a rare and severe immune reaction that can occur in those who had SARS-CoV-2 infection weeks or months before receiving a COVID-19 vaccine and may lead to significant organ damage.
“There were several high profile deaths, like Williams’ with previous COVID-19, who then received one or two vaccine doses, experienced a hyperimmune response, and died,” Dr. Noorchashm said.
Dr. Noorchashm attempted to bring this issue to the attention of vaccine manufacturers and the U.S. Food and Drug Administration (FDA) when COVID-19 vaccines were first authorized. He was concerned those with prior infection required to get vaccinated under vaccine mandates could be at an increased risk of experiencing an adverse event and called for screening antibody levels before vaccinating.
“In general, a standard of care is to screen before you vaccinate to assess whether one has immunity,” Dr. Noorchashm said. “Because COVID-19 vaccines have a side-effect profile that includes myocarditis and blood clots, even if infrequent, when you’re talking about vaccinating millions of people within a short span of time with an experimental vaccine, you have to be circumspect about that. At the very least, we need to have technology available to those who want to know whether they really need the vaccine.”
Despite these concerns, the FDA issued guidance in May 2021 “reminding the public and health care providers that results from currently authorized SARS-CoV-2 antibody tests should not be used to evaluate a person’s level of immunity or protection from COVID-19 at any time, and especially after the person received a COVID-19 vaccination.”
Dr. Noorchashm found the FDA’s guidance concerning because allowing physicians to assess antibody levels before vaccination can prevent potentially severe adverse effects and ensures only those who need a vaccine are vaccinated.
“A standard of care is to assess immunity by screening, so why not make that available to citizens? Why was there such a resistance to that?” Noorchashm asked. “The FDA provided no basis for its guidance recommending against screening for antibodies—which is indicative of previous SARS-CoV-2 infection. If the purpose is to make sure everyone is immune, that’s very different from making sure everyone gets vaccinated.”
According to the study in Clinical Infectious Diseases, vaccine manufacturers did not systematically assess individuals with a previous history of SARS-CoV-2 infection in pre-licensure trials of COVID-19 vaccines. Still, Dr. Noorchashm, who doesn’t dispute the efficacy of COVID-19 vaccines, said it would have been simple to do so.
He also noted what the study didn’t capture—those individuals who had already acquired natural immunity through previous infection but died as a result of vaccination and weren’t able to answer a questionnaire.
“I’m glad more research is being done on this, but it could have easily been done years ago during the pandemic,” Dr. Noorchashm said.
