Should my child get their second vaccine shot, despite heart inflammation risks?

TORONTO -

With back to school just around the corner, many parents of teenaged children, especially boys, may be wondering whether to give their child a second COVID-19 vaccine shot or whether one shot is enough when balanced against the rare, but potential risk of an inflammation of the heart.

In most cases, experts recommend that both doses be given to all who are eligible. They say the risks associated with catching and spreading COVID-19 are greater than the risks associated with the rare inflammation.

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"The risks are very small for a syndrome that does not seem to be very significant, that is treatable without long term sequela," says Dr. Earl Rubin, the director of the Infectious Diseases Division of the Montreal Children's Hospital. Rubin has three children of his own, including adolescents and a son who is 21.

"So you put all of that together on a balance of probabilities -- what did I do for my own 21 year old son? I said absolutely."

There have been a small number of instances both in Canada and globally where those immunized with the mRNA COVID-19 vaccines developed myocarditis and/or pericarditis. Myocarditis is an inflammation of the heart muscle, which can affect how the heart pumps, causing abnormal heart rhythms. Pericarditis is when the lining around the heart is inflamed. Viral infections, including SARS-CoV-2, the virus that causes COVID-19, can also cause these types of inflammation.

Several studies have documented the rare incidences, with more cases involving male adolescents and young men, often following the second dose. Patients experienced severe chest pain and abnormal electrocardiogram results, often less than a week after receiving the vaccination.

In Canada, there have been 485 confirmed cases of myocarditis/pericarditis reported as of August 13, 2021, with symptoms appearing between a few minutes to three months after vaccination. The rate of incidences are less than one case per 100,000, according to data from the Public Health Agency of Canada (PHAC).

"You're really looking at a very infrequent manifestation," Rubin said, adding that often a non-steroidal, anti-inflammatory drug like Advil can control the symptoms.

"Although they can be symptomatic with chest pain, 99 point something per cent resolved without ... any problems at all."

In contrast, a preliminary study out of the U.S. that has yet to be peer-reviewed found that in the first year of the pandemic, adolescent males between the ages of 12 and 17 developed myocarditis within three months of being infected with COVID-19 at an equivalent rate of about 45 cases per 100,000, far higher than from the mRNA vaccinations.

Both the National Advisory Committee on Immunization (NACI) and the U.S. Centers for Disease Control and Protection (CDC) recommend that all eligible individuals without contraindications, including children aged 12 and up, be fully vaccinated even when myocarditis and pericarditis side-effects are taken into consideration. NACI does recommend, however, that those who experienced an inflammation of the heart after the first dose should wait to get their second shot until there is more information.

"The pluses of vaccination continue to outweigh the minuses," Dr. Kevin Harris, a pediatric cardiologist at BC Children’s Hospital, said in a July news release on heart inflammation risks related to the mRNA vaccines.

"It’s also about helping to protect others, including immunocompromised children who may not be adequately protected by vaccine or younger children for whom vaccines are not approved for use at this time."

Myocarditis and pericarditis symptoms include chest pain on exertion, shortness of breath, a rapid, fluttering or pounding heart. While Rubin says there is no research published on the subject, he recommended to his son and others that they avoid strenuous exercise for the first week after getting their shot, out of an abundance of caution.

IS ONE DOSE ENOUGH?

Rubin says that with the first, original COVID-19 virus, or even the Alpha variant first recorded in the U.K., a single dose provided “decent” short-term protection. But the Delta variant is something different. 

Two doses are necessary to get 85 to 95 per cent protection, he notes, with one dose alone only providing about 35 per cent protection against the highly transmissible variant.

"One dose is not as effective. It doesn't give you as [much] long-term protection," he said. His most important message is that everyone who is eligible should get fully vaccinated.

"There are tremendous downsides to not getting vaccinated and not getting fully vaccinated … The Delta variant is incredibly transmissible. One infected person can infect up to six to eight non-protected people around them, so the numbers are going to skyrocket. So if you combine inadequate vaccination or no vaccination with that high transmissibility, we're in for much higher numbers."

Even if the percentage of children who require hospitalization due to COVID-19 is extremely low overall, Rubin said, the more cases of COVID-19 infections there are among children, the higher the number of kids who will end up requiring hospital care.

"There is always concern when it comes to something that people don't know, people don't understand. We are always very concerned about what we are doing to ourselves, but more importantly, to our children," he said.

"At this point in time for what we do know, there are much greater risks with not being vaccinated or adequately vaccinated, with getting COVID itself, and the side effects of COVID itself, rather than the rare side-effects of the vaccine. I can't emphasize that more strongly."