Young male BioNTech vaccine recipients have the highest risk of developing heart inflammation after their second Covid-19 jab, with more than 18 cases among one million doses, according to the University of Hong Kong, citing findings from the first vaccine effects database.
But its experts described the risk as "clinically low" and "as slim as winning the Mark Six top prize" as the prevalence of the heart condition is 18.94 for BioNTech and 5.22 for Sinovac recipients per million doses.
The most common Sinovac adverse effect in senior recipients is blood clots.
The research was based on analysis of data from the Department of Health and the Hospital Authority of recipients' responses in weeks two and four after vaccinations from February 23, 2021 to March 31, 2022.
Hospitals saw a total of 1,213 cases of patients warded due to heart inflammation.
Excluding those who had a relevant medical history, HKU identified a total of 1,029 people diagnosed with heart inflammation as of the end of this March.
After further excluding 107 patients who were infected during the study, among a total of 922 patients, the risk of developing heart inflammation within 14 days after getting the second BioNTech dose rose by 10.81 times, while males and people under 30 also have higher risks than other groups.
Francisco Lai Tsz-tsun, research assistant professor of pharmacology & pharmacy, said since the sample size of people aged from 12 to 29 was small, the statistics could have random errors.
But he said the benefits of getting jabbed still substantially outweigh risks, and used "winning Mark Six" as an example to gauge the absolute risk of jabbers getting heart inflammation to still be very low.
"We should highlight that these kinds of adverse events are still very rare. Even if we are using big data to do our research, we only identified a very rare incidence. So we do think safety is good overall," he said.
"The risks of getting Covid and its related complications far outweigh the possible rare adverse events brought by the jabs."
The university also conducted data analysis from February 23, 2021, to January 31, 2022, on the elderly and patients with prior diabetic or chronic disease conditions having severe adverse effects after jabs.
It found that of 620,000 seniors over 60 who received at least one Sinovac dose, the adjusted incidence rate ratio of having a severe allergy - was 2.61 - or 0.61 people in every 100,000.
Associate professor Esther Chan Wai-yin said people with mental illness have a lower vaccination rate when compared with locals overall. She urged more work in educating families to bring them for jabs as their chances of complications tend to be higher if they were infected.
The most common Sinovac adverse effect in senior recipients is blood clots.
The research was based on analysis of data from the Department of Health and the Hospital Authority of recipients' responses in weeks two and four after vaccinations from February 23, 2021 to March 31, 2022.
Hospitals saw a total of 1,213 cases of patients warded due to heart inflammation.
Excluding those who had a relevant medical history, HKU identified a total of 1,029 people diagnosed with heart inflammation as of the end of this March.
After further excluding 107 patients who were infected during the study, among a total of 922 patients, the risk of developing heart inflammation within 14 days after getting the second BioNTech dose rose by 10.81 times, while males and people under 30 also have higher risks than other groups.
Francisco Lai Tsz-tsun, research assistant professor of pharmacology & pharmacy, said since the sample size of people aged from 12 to 29 was small, the statistics could have random errors.
But he said the benefits of getting jabbed still substantially outweigh risks, and used "winning Mark Six" as an example to gauge the absolute risk of jabbers getting heart inflammation to still be very low.
"We should highlight that these kinds of adverse events are still very rare. Even if we are using big data to do our research, we only identified a very rare incidence. So we do think safety is good overall," he said.
"The risks of getting Covid and its related complications far outweigh the possible rare adverse events brought by the jabs."
The university also conducted data analysis from February 23, 2021, to January 31, 2022, on the elderly and patients with prior diabetic or chronic disease conditions having severe adverse effects after jabs.
It found that of 620,000 seniors over 60 who received at least one Sinovac dose, the adjusted incidence rate ratio of having a severe allergy - was 2.61 - or 0.61 people in every 100,000.
Associate professor Esther Chan Wai-yin said people with mental illness have a lower vaccination rate when compared with locals overall. She urged more work in educating families to bring them for jabs as their chances of complications tend to be higher if they were infected.