How vaccination can defend the heart from COVID-19

We know that COVID-19 vaccines are effective at preventing progression of severe disease - but it’s been unclear to what extent they protect against secondary complications of the virus, such as its devastating impact on the cardiovascular system.

Now, new research from the Icahn School of Medicine at Mount Sinai, New York, USA indicates they can.

Serious SARS-CoV-2 infection has been linked to higher rates of major adverse cardiac events (MACE), including myocarditis, pericarditis, blood clots and inflammation, both during infection and after recovery.^[]

Researchers set out to find out whether vaccination could reduce these detrimental effects. They discovered that fully vaccinated patients have a 41% lower risk of MACE than non-vaccinated patients.^[][] Even for partially vaccinated patient, the risk falls by 24%.

Substantially lower risk

This study uses one of the most extensive national COVID-19 databases, the US National COVID Cohort Collaborative (N3C), with data on over 1.9 million patients aged 18-to-90 years who were infected with SARS-CoV-2 between 1 March 2020 and 1 February 2022.

Most – 88.7% - were not vaccinated before infection, with 10.1% (195,136) fully vaccinated and 1.2% partially vaccinated.

Though 0.74% of non-vaccinated individuals were diagnosed with MACE, this affected only 0.54% of fully vaccinated and 0.70% of partially vaccinated people. Lead author Joy Jiang, a MD/PhD candidate at Icahn School of Medicine at Mount Sinai, explained: “To our surprise, even partial vaccination was associated with lower risk of adverse cardiovascular events.”^[]

The research builds on similar results from a 2022 Korean study that found fully vaccinated patients had a decreased risk of myocardial infarction (MI) and ischemic stroke after COVID-19 infection. However, the number of patients included was less than an eighth of the US database and 73% of those were fully vaccinated.^[] The US study’s size, and the inclusion of partially vaccinated people, gives it real strength in adding to our understanding of how SARS-CoV-2 impacts our cardiovascular system.

Encouraging results

Senior author Professor Girish Nadkarni, Icahn School of Medicine at Mount Sinai said: “While we cannot attribute causality, it is supportive evidence that vaccination may have beneficial effects on a variety of post-COVID-19 complications.”^[]

Though the size of the study is a strength, it only looked at vaccines widely distributed in the US - excluding the AstraZeneca COVID-19 vaccine - meaning results could be different in the UK or other countries. The database also did not take into account reinfections or newer variants.

Nevertheless, it helps to elucidate the effects of both COVID-19 infection and vaccination on the body.

Three years since the World Health Organization declared COVID-19 a pandemic, we are still finding out more about the detrimental impact of SARS-CoV-2 on the body. One recent study found that deaths from MI in the US have increased by up to 30% since the beginning of the pandemic, something the study authors describe as “more than coincidental”.^[]The results of Icahn School of Medicine’s study help us understand the extent to which we can prevent these harmful effects.

It can also improve our understanding of vaccination risks; minor increased risks of myocarditis following vaccination were well-publicized and led to backlash, but this study helps to demonstrate the much greater risk of harm to the cardiovascular system from infection.^[]

Emphasizing that vaccination could protect against cardiac events could encourage vaccination,^[] Jiang stated in a press release: “Given the magnitude of SARS-CoV-2 infection worldwide, we hope our findings could help improve vaccination rates, especially in individuals with coexisting conditions.”