Nature sub-issue: Myocarditis risk associated with vaccination or coronavirus infection

The widespread vaccination of the new crown vaccine has effectively protected people's health, but with the increase in the number of vaccinated, many side effects have also begun to appear, for example, the United States, Europe, Israel and other places have reported that many young people have myocarditis or pericarditis after vaccination, especially mRNA vaccine
.
So, is vaccination associated with the risk of heart diseases such as myocarditis? Does the risk of myocarditis from vaccination outweigh the risk of myocarditis with coronavirus?

Recently, researchers from the University of Oxford published a title in Nature Medicine, a top international medical journal: Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection (risk of myocarditis, pericarditis and arrhythmias associated with vaccination or coronavirus infection).

This is the largest study to date on acute cardiac events following vaccination or infection with the new coronavirus, and the first study
to compare the risk of cardiac events between different vaccines and new coronavirus infections.
The results showed that adenovirus or mRNA vaccination in adults was associated with a small increased risk of myocarditis, and the increased risk of myocarditis associated with both mRNA vaccinations was only present in
people under 40 years of age.
Infection with the new coronavirus is associated with
a significantly increased risk of myocarditis, pericarditis and arrhythmias.

The study assessed 1-10 additional myocarditis events per million adults in the month following vaccination, which is significantly lower than the 40 additional myocarditis events
per million adults after coronavirus infection.

Although no adverse events such as myocarditis and pericarditis have been observed in clinical trials of the new crown vaccine, a large number of suspected cases have begun to be reported
as these vaccines are administered in the general population.

Between 1 December 2020 and 24 August 2021, a total of 38615491 adults in England received at least one dose of the Covid vaccine (32095748 of which received two doses), 20615911 ChAdOx1 vaccine (95.
8% of whom received two doses), and 16993389 BNT162b2 vaccine (of which 70.
5% received two doses), 1006191 people who received mRNA-1273 vaccine (36.
7% of whom received two doses), and 3028867 of those who received at least one dose tested positive
for the new crown.

Of the 38615491 adults vaccinated in the included studies, 1615 (0.
004%) were hospitalized or died
from myocarditis at any time during the study period (before or after vaccination).
Of these, 397 (0.
001%) occurred within 1-28 days
after vaccination.
Of the 1,615 patients admitted or died of myocarditis, 359 tested positive for Covid, 287 of them before
vaccination.
A total of 114 people died from myocarditis (23 of whom tested positive for Covid).

Of the 38615491 adults vaccinated in the included studies, 1574 (0.
004%) were admitted or died
from pericarditis at any time during the study period (before or after vaccination).
Of these, 356 cases (0.
001%) occurred within 1-28 days
after vaccination.
Of the 1,574 patients admitted or died from pericarditis, 188 tested positive for Covid, 154 of whom were before
vaccination.
A total of 31 people died from pericarditis (6 of whom tested positive for Covid).

Of the 38615491 adults vaccinated in the included studies, 385508 (1.
0%) were hospitalized or died due to arrhythmias at any time during the study period (before or after vaccination), of which 86,754 (0.
2%) occurred between 1 and 28 days
after vaccination.
Of those admitted or died, 39,897 tested positive for COVID and 29,694 tested positive
before vaccination.
A total of 7,795 people died from arrhythmias (1,108 of whom tested positive for Covid).

Further analysis showed an increased
risk of myocarditis within 1-28 days after the first dose of ChAdOx1 or BNT162b2 or the first and second doses of mRNA-1273 vaccine.
And myocarditis also increased
after testing positive for the new crown.

Specifically, there were 2, 1, and 6 more myocarditis events per 1 million people in 28 days after the first dose of ChAdOx1, BNT162b2, or mRNA-1273, respectively, and 10 more myocarditis events in 1 million people within 28 days after the second dose of mRNA-1273
.

In contrast, 40 more myocarditis events per 1 million people occurred in 28 days after testing positive for covid, in addition, an increased
risk of pericarditis and arrhythmias was observed.
An increased risk of arrhythmias was observed with the second dose of mRNA-1273, while other vaccines did not
.
Subgroup analysis by age group showed that the increased risk of myocarditis associated with both mRNA vaccinations was only present in
people under 40 years of age.

Overall, this large-scale study of tens of millions of people quantifies for the first time the risk of several rare adverse cardiac events (myocarditis, pericarditis, arrhythmia) associated with three types of
vaccination and viral infections.
The results showed that adenovirus or mRNA vaccination in adults was associated with a small increased risk of myocarditis, compared with a large increased risk of hospitalization or death due to myocarditis, pericarditis, and
arrhythmias.

It is worth mentioning that on December 14, 2022, researchers from the Health Science Center of the University of New Mexico in the United States published a report in the journal Viruses entitled: COVID-19 Associated Myocarditis Clinical Outcomes among Hospitalized Patients in the United States: A Propensity Matched Research paper
that analyzes the National Inpatient Sample.

This study of 1659040 new crown hospitalized patients (of which 6355 were new crown complicated myocarditis) showed that the inpatient mortality rate of new crown complicated myocarditis was significantly higher than that of new crown hospitalized patients without myocarditis (30.
5% vs 13.
1%)
.