In a recent study published in Heart, researchers explored the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination on thromboembolic and cardiovascular complications risk following coronavirus disease 2019 (COVID-19).
Study: The role of COVID-19 vaccines in preventing postCOVID-19 thromboembolic and cardiovascular complications. Image Credit: BaLL LunLa/Shutterstock.com
Background
COVID-19 vaccinations, licensed for emergency use in December 2020, have demonstrated efficacy against SARS-CoV-2 infection, hospitalization, and death.
However, there are concerns due to uncommon thromboembolic events and the association of messenger ribonucleic acid (mRNA)-based vaccinations with rare myocarditis cases. SARS-CoV-2 infection can cause cardiac and thromboembolic events, lasting up to a year following infection.
Although these problems are uncommon, they burden afflicted individuals significantly, and the global incidence and prevalence might increase.
Recent studies show that SARS-CoV-2 vaccination may protect against these issues, although data is scarce since most studies include specialized populations and exclude long-term consequences.
About the study
In the present staggered cohort study, researchers investigated whether SARS-CoV-2 vaccines reduce post-infection complication risk.
The researchers examined national immunization campaign data from the United Kingdom (UK), Estonia, and Spain. They used the Clinical Practice Research Datalink (CPRD) Gold and Aurum databases to obtain UK data.
They retrieved Spanish data from the Information System for the Development of Research in Primary Care (SIDIAP) database and Estonian data from the CORIVA database.
They linked the datasets to the Observational Medical Outcomes Partnership (OMOP) Common Data Model for federated analysis.
The study population included individuals listed in the databases for ≥180 days before study initiation with no prior COVID-19 or SARS-CoV-2 vaccination history at baseline. The researchers divided vaccination dissemination into four stages, each with predetermined enrolment times, considering COVID-19 vaccinations as time-varying.
Across nations, the first cohort included older individuals, the second included those prone to severe SARS-CoV-2 infection, the third included individuals aged ≥40 years, and the fourth comprised those aged ≥18 years. In all cohorts, individuals who received their first vaccination during the recruitment period formed the vaccinated cohort, with the vaccination date considered the index date.
The study outcomes included SARS-CoV-2 infections followed by prespecified cardiovascular or thromboembolic events within 12 months of infection without a record of the same in the six months before infection.
Post-COVID-19 outcome events included venous thromboembolism (VTE), arterial thromboembolism/thrombosis (ATE), and heart failure (HF), recorded in windows of 0 to 30 days, 31 to <91 days, 91 to <181days, and 181 to 365 days after acute COVID-19.
The team followed up with the participants until the end of data availability, mortality, change in study exposure status (initial vaccination for unvaccinated individuals), or study outcome.
The researchers used empirical calibration while doing propensity score matching to reduce confounding. The variables included age, gender, domicile, index date, database observation duration, number of prior outpatient visits, previous SARS-CoV-2 antigen testing and polymerase chain reaction (PCR), regional-wise vaccination, and COVID-19 incidence.
The team conducted Fine-Gray modeling to determine the sub-distribution hazard ratio (sHR) values and random effects meta-analytical research using staggered groups and COVID-19 datasets.
They used the least absolute shrinkage and selection operator (LASSO) regression to identify more variables. Sensitivity analyses included censoring follow-up for vaccinated individuals during their second vaccination and focusing on post-COVID-19 outcomes a year after acute infection.
Results
The researchers analyzed data from 10.2 million COVID-19 vaccines and 10.4 million unvaccinated individuals. Vaccination was related to lower risks of thromboembolism, arterial thromboembolism, and heart failure in the acute and post-acute SARS-CoV-2 infection period.
The meta-analytical sHR were 0.2, 0.5, and 0.5 for 30 days following COVID-19, whereas sHR for 91 to 180 days were 0.5, 0.7, and 0.6, respectively.
Incidences followed a similar trend across all databases, with higher outcome rates among older individuals and decreasing frequency as infection duration increased in all cohorts.
Stratified analyses by vaccination revealed similar correlations, except ChAdOx1, which was unrelated to decreased venous and arterial thromboembolism risks in the final post-acute window.
The sensitivity analyses were consistent with the primary findings, indicating the robustness of the results.
Meta-analytic estimations preferred BNT162b2 (sHR, 0.7) for venous thromboembolism during 0–30 days after infection, but there were no differences for post-acute venous thromboembolism or other outcomes.
Conclusion
Overall, the study found that SARS-CoV-2 vaccination significantly decreased the incidence of acute thromboembolic and cardiac sequelae after acute COVID-19. This reduction was likely due to vaccine-induced immunity, which reduced the likelihood of COVID-19 incidence and severity.
The lowered risk in vaccinated individuals lasted up to a year for post-COVID-19 venous thromboembolism, arterial thromboembolism, and heart failure.
The study emphasizes the potential advantage of COVID-19 immunization in lowering post-COVID-19 cardiac and thromboembolic complication risks, with a higher impact on acute COVID-19 outcomes.
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