Developing long COVID appears to be more likely after two doses of a COVID-19 vaccine, suggesting that the spike protein may contribute to the phenomenon.
People who receive two doses of a COVID-19 vaccine may be more likely to develop long-COVID, a new study finds.
In the study published in PLOS One, researchers examined data from 487 and 371 individuals at four weeks and six months post-SARS-CoV-2 infection, respectively, to estimate the incidence, characteristics, and predictors of long COVID among patients. Long COVID symptoms were reported by 29.2 percent of participants four weeks following infection. This number dropped to 9.4 percent at six months, indicating symptoms may diminish over time.
Researchers found that the greater the severity of infection a patient had, the more likely they were to experience long COVID. The incidence of long COVID at four weeks of follow-up in those who experienced mild/moderate disease was 23.4 percent compared with 62.5 percent in those with severe cases.
At six months, the incidence of long COVID was considerably lower. For those with mild/moderate infection, only 7.2 percent reported symptoms compared with 23.1 percent in those with severe/critical cases. The most commonly reported symptom was fatigue. Other symptoms included cough, cognitive dysfunction or brain fog, and loss of taste and smell.
During the four-week follow-up, patients were more likely to experience long COVID if they had preexisting medical conditions, a higher number of symptoms during the acute phase of COVID-19 illness, if their infection was more severe or resulted in hospitalization, or if they had received two COVID-19 vaccine doses.
Although previous vaccination was associated with long COVID, the authors could not find “any interaction effect of COVID-19 vaccination and acute COVID-19 severity on causing Long COVID.”
This implies that prior vaccination “was independently associated with the occurrence of long-COVID,” cardiologist Dr. Peter McCullough explained in a recent Substack post.
How COVID-19 Vaccines May Contribute to Long COVID
Nearly 7 percent of U.S. adults surveyed in 2022 said they’ve experienced long COVID—a condition commonly thought only to be associated with SARS-CoV-2 infection. Although definitions of long COVID differ, the Centers for Disease Control and Prevention broadly defines long COVID as “signs, symptoms, and conditions that continue to develop after acute COVID-19 infection” that can last for “weeks, months, or years.” The term “long COVID” is also used to refer to post-acute sequelae of SARS CoV-2 infection (PASC), long-haul COVID, and post-acute sequelae of COVID-19.
