Just SIX in 1 million people develop rare heart inflammation after a second dose of the Covid vaccine – 85% less than the rate among the unvaccinated, study finds
- Less than out of every one million people develop myocarditis after the first shot of a Covid vaccine, and around six develop it after the second jab
- Unvaccinated participants were found to be eight times as likely to develop heart inflammation as those who do receive the shots
- All participants who developed condition after vaccination were males, and officials have warned that younger men are vulnerable to heart inflammation
- The CDC reports that just under 1,500 out of every one million hospitalized Covid patients develop myocarditis
Americans are much more likely to develop rare heart inflammation after the second dose of a COVID-19 vaccine compared to the first dose, a new study suggests.
Researchers from Kaiser Permanente Southern California (KPSC) found that less than one out of every one million people who receive the first dose of either the Pfizer-BioNTech or Moderna vaccine will develop the condition within the next ten days.
Comparatively, six out of every million will develop heart inflammation within ten days of the second dose.
But unvaccinated people are still at a much higher risk.
The team found that 47.5 out of every one million people who had not had their shots and underwent health screenings had the condition.
The findings suggest that myocarditis is a rare side effect of the vaccine, and people should feel safe in receiving the jabs.
People who receive the Covid vaccine are seven times as likely to develop heart inflamation after the second dose of the jab when compared to the first. Those who are unvaccinated are significantly more likely to develop myocarditis, however
Myocarditis, the medical name for heart inflammation, is a known side effect of viral infections like Covid.
The condition has also been discovered as a potential side effect of the vaccines, with younger males being at an especially high risk but at a much lower rate than if they had contracted the virus.
For the study, published in JAMA Internal Medicine on Monday, the KPSC team gathered data from more than 2.3 million patients in its Southern California health care system.
Researchers investigated medical records of participants to find who had received medical care for myocarditis in the ten days following the jab.
Two participants were found to have developed myocarditis after receiving the first shot, or 0.8 out of every one million people.
By comparison, more that 2.2 million participants returned for screening after the second shot, with 13 – or 5.8 out of every million – having the condition.
This means that people are seven times more likely to develop the condition after the second dose rather than the first.
Those that developed the condition were evenly split between participants who received the Pfizer and Moderna shots.
For a control group, researchers also gathered data from 1.5 million unvaccinated people over the course of the study period.
Around 47.5 out of every one million unvaccinated people were found to have developed the condition.
While those in the control group were not specifically selected because they had previously contracted the virus, it is likely that Covid did cause the condition in unvaccinated people.
This means unvaccinated people are eight times as likely to develop myocarditis than people are after receiving the shots.
Every participant who was found to develop heart inflammation after receiving the vaccine in the study was a male.
This is a known trend, with the Centers for Disease Control and Convention (CDC) warning that younger males are particularly vulnerable to myocarditis after receiving the vaccine.
A Gallup poll from the end of July found that fear of side effects – of which the most common serious side effect is myocarditis – is the most cited reason for vaccine hesitancy.
This KPSC study finds that people who do receive the jabs are much more likely to experience these negative side effects than those who do not get the shots.
Data from the CDC confirms this as well, with the agency reporting that nearly 1,500 out of every million people who are hospitalized with Covid develop heart inflammation.
Heart inflammation can often lead to fatigue, shortness of breath and chest pain for patients.
People with inflamed hearts are at a higher risk for heart failure, heart attacks and strokes.
Attempting strenuous physical activity with an inflamed heart could also potentially lead to sudden cardiac arrest, or even death.