A new study suggests that Covid-19 vaccines are safe for patients with cardiovascular disease.

According to the study’s author, these findings show that having cardiovascular disease “should not prevent people from getting vaccinated against Covid-19”.

The study from Hong Kong is the first to investigate the association between Covid-19 vaccines and the risk of major adverse cardiovascular events in people with cardiovascular disease.

It involved almost 230,000 patients with cardiovascular disease. The first two doses of vaccine were included in the analyses.

Established cardiovascular disease included coronary heart disease, cerebrovascular disease, peripheral vascular disease and prior interventions such as stenting. Major adverse cardiovascular events included myocardial infarction, stroke, revascularisation or cardiovascular death.

Of the almost 230,000 participants, 1,764 had experienced a major adverse cardiovascular event after vaccination.

The researchers used the self-controlled case series study design, which was developed to assess the risk of adverse events after vaccination. Each patient was compared with himself/herself for the risk of an adverse event up to 27 days after each vaccine dose (exposure period) versus the non-exposure baseline period.

“A traditional cohort study would compare the vaccinated group with the unvaccinated group but the two groups could have different baseline characteristics. A self-controlled case series avoids the issue of differences between groups since each individual acts as his/her own control,” explained the study’s author, Dr Esther Chan, of the University of Hong Kong.

The study estimated incidence rate ratios to compare the risk of adverse events during the 27 days after vaccination compared to the baseline period. These analyses were carried out for both the first and second doses of the vaccine.

The researchers found no evidence of an elevated risk of an adverse event after the first or second dose of a Covid-19 vaccine.

“Our study showed that pre-existing cardiovascular disease should not prevent people from getting vaccinated against Covid-19. Vaccination is particularly important for this group since cardiovascular disease is associated with worse outcomes and a higher risk of death after Covid-19 infection,” Dr Chan noted.

She pointed out that the findings were consistent for men and women, people aged under and over 65 years and patients with different underlying cardiovascular conditions.

“The results should provide reassurance about the cardiovascular safety of these vaccines," Dr Chan added.

The study focused on BNT162b2 and CoronaVac, the only COVID-19 vaccines authorised for emergency use in Hong Kong. Details are published in Cardiovascular Research, a journal of the European Society of Cardiology.