Do COVID vaccines prevent new medical conditions?

The risks of prolonged COVID symptoms and the incidence of hypertension, diabetes and new-onset heart disease were lower in vaccinated patients with breakthrough infection compared to those with COVID who were not vaccinated, according to an extensive analysis of medical records in the United States.

Compared with those who were not vaccinated, the relative risks were 0.33 for hypertension (95% CI 0.26-0.42), 0.28 for diabetes (95% CI 0, 20-0.38) and 0.35 for heart disease (95% CI 0.29-0.44) at 90 days. after the diagnosis of COVID for the vaccinated group, reported Grace McComsey, MD, of Case Western Reserve University in Cleveland, Ohio, and her colleagues.

Moreover, the risk of death 90 days later was also significantly lower (RR 0.21, 95% CI 0.16-0.27), the authors wrote in Open Forum on Infectious Diseases.

“Differences in risk at 28 and 90 days between the vaccinated and unvaccinated cohorts were observed for each outcome and there was sufficient evidence … to suggest that these differences were attributed to the vaccine,” they wrote.

McComsey and colleagues looked at retrospective data from TriNetX, described as “a large national health research network” of 57 US centers. Participants were adults with SARS-CoV-2, confirmed by PCR testing, who sought care from September 2020 to December 2021. They were stratified into two groups: vaccinated with breakthrough infection and unvaccinated patients. Long COVID, or “post-acute sequelae of COVID,” was defined as new, ongoing, or recurrent symptoms occurring 4 weeks or more after initial COVID infection. Patients were also matched by baseline comorbidities.

Overall, 1,578,719 patients with confirmed COVID were identified, of which 25,225 (1.6%) had documented COVID vaccination. In the vaccinated cohort, the average age was approximately 55 years, approximately 60% were female, and 68% were Caucasian. At baseline, 47% suffered from hypertension, 23% from diabetes and 13% from chronic kidney disease. In the unvaccinated cohort, the mean age was 43 years, 56% were female, and 62% were Caucasian. A smaller proportion also had pre-existing conditions (28% hypertension, 14% diabetes and 6% chronic kidney disease), but none of these differences were significant after matching.

At 90 days after COVID diagnosis, the authors found that the risk of new or persistent findings was lower in the vaccinated cohort compared to the unvaccinated cohort. The incidences (per 1,000) in the vaccinated versus unvaccinated cohort, respectively, were 7.19 versus 20.26 for heart disease, 6.45 versus 25.53 for mental disorders, 6.42 against 19.59 for hypertension and 2.69 against 9.69 for diabetes.

The vaccinated cohort also saw lower risks of new respiratory symptoms (RR 0.54, 95% CI 0.50-0.57), headache (RR 0.39, 95% CI 0.34 -0.45), fatigue (RR 0.48, 95% CI 0.43-0.52), pain (RR 0.34, 95% CI 0.28-0.42) and diarrhea or constipation (RR 0.44, 95% CI 0.40-0.49) at 90 days.

The authors noted that in addition to the usual post-COVID symptoms, such as headache, fatigue, body aches, and respiratory and gastrointestinal symptoms, they found that vaccination was associated with a lower risk of diseases. new onset such as hypertension, diabetes, heart disease and mental disorders. They “very carefully captured new findings” that occurred post-COVID, not just pre-existing medical conditions, the group argued.

“We hypothesize that [vaccination’s] effect on reducing inflammatory responses during the acute phase also explains the lower levels of all [post-acute sequelae of SARS-CoV-2] results observed in our study among the vaccinated group,” McComsey and coauthors wrote.

Data limitations include the use of electronic medical records, the fact that the true prevalence of these post-COVID symptoms is unknown, as many asymptomatic patients have not been tested for the virus, and vaccination status may be a source of bias, as those who were likely vaccinated may have been more likely to seek or receive medical care.

  • Molly Walker is associate editor and covers infectious diseases for MedPage Today. She is the winner of the J2 Achievement Award 2020 for her COVID-19 coverage. Follow


This study was supported by the Clinical and Translational Science Collaborative of Cleveland of the National Center for Advancing Translational Sciences component of the NIH and NIH Roadmap for Medical Research.

Zisis has disclosed no conflicts of interest.

McComsey disclosed support from Tetraphase, Roche, Vanda, Astellas and Genentech, Gilead, Merck, ViiV/GSK, Theratechnologies and Janssen.

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