No Increased Risk of Serious Adverse Events After COVID-19 Vaccination
After an 18-month study, investigators determined none of the diseases examined were more frequent among the vaccinated than among the non-vaccinated.
A cohort study of the entire population of an Italian Province found COVID-19 vaccination did not increase the risk of adverse events, including heart attack, stroke, cardiac arrest, myocarditis, pericarditis, or deep vein thrombosis.
From January 2021-July 2022, the study, published in Vaccines, assessed the incidence of potentially vaccine-related serious adverse events by COVID-19 vaccination status. The investigators extracted data on all deaths and hospitalizations due to severe cardiovascular diseases, pulmonary embolism, and deep vein thrombosis from the National Healthcare System.
This study is currently the only one in the world to monitor its participants for more than a year, considering age, gender, and clinical risk of the vaccinated and unvaccinated patients.
During the 18-month follow-up period, 2097 individuals were hospitalized and 5743 died of potentially vaccine-related serious adverse events. Notably, the COVID-19 vaccine recipients (n = 259821) did not exhibit an increased risk of all-cause death, non-COVID-19 death, or any potentially vaccine-related serious adverse events when compared to the unvaccinated cohort (n = 56494).
These results remined consistent across gender, age, vaccine type, and COVID-19 infection status. They continued to show no variance in Cox models that adjusted for age, gender, infection status, and various comorbidities.
“The results obtained clearly show that there was no increased risk of serious diseases among the vaccinated,” said study coordinator Lamberto Manzoli, a medical epidemiologist and professor at the University of Bologna Department of Medical and Surgical Sciences.
The findings also confirmed that individuals vaccinated against COVID-19 were more protected against the virus than unvaccinated individuals who recovered from infection. Receiving even 1 dose of any approved COVID-19 vaccine significantly reduced the risk of mortality and potentially vaccine-related serious adverse events.
Additionally, there was a higher incidence of the monitored diseases (severe cardiovascular diseases, pulmonary embolism, deep vein thrombosis) among persons who had only 1 or 2 doses of a COVID-19 vaccine, compared to those who received 3 or more vaccine doses.
“There were isolated adverse cases, but the safety profile of the vaccines used during the pandemic was confirmed: it is now important to continue the follow-up over a longer period,” Manzoli emphasized.
