As of May 28, 2021, 25 cases of cases of myocarditis and pericarditis have been reported in the country out of the 26 million doses administered, according to the Public Health Agency of Canada (PHAC).
In the United States, seven teenage boys who received the Pfizer shots in April and May were diagnosed with the condition after they developed chest pain within four days of getting their second dose.
Meanwhile, Israel’s health ministry says 275 cases — mostly in young men who received Pfizer’s COVID-19 vaccine — of myocarditis were reported between December 2020 and May 2021 among more than 5 million vaccinated people
It is common for a vaccine to have side effects. So far, no clear link has been established between a heart reaction and any of the COVID-19 vaccines and the cases are rare, but experts say the evidence should be taken seriously.
“We currently do not see any higher rates than would be expected in the general population, but it is something that we need to continuously monitor,” said Dr. Theresa Tam, Canada’s chief public health officer, during a news conference on June 4.
We take a closer look at myocarditis, its symptoms and the risks associated with them.
Myocarditis is the inflammation of the heart muscle, while pericarditis is the inflammation of the lining around the heart.
Both are caused by a viral infection, although other infections can also lead to an inflammation of the heart.
“They’re not common conditions, but they’re also not uncommon,” said Dr. Mansoor Husain, a cardiologist at the Toronto General Hospital and professor of medicine at the University of Toronto.
“They are seasonal. We get clusters of cases appearing sort of altogether over certain weeks that are seasonal.”
However, clusters of myocarditis cases are usually not reported following the annual influenza vaccine, Husain noted.
Symptoms for myocarditis typically include:
- Chest pain
- Shortness of breath
- Palpitations or irregular heart rate
People can also experience non-specific symptoms of any viral infection such as fever, chills and muscle aches and pains, said Husain.
Among the cases reported in Canada, the onset of symptoms ranged from five hours to 92 days after the administration of a COVID-19 vaccine.
What are the risks?
Among the 25 cases reported so far in Canada, 15 were females and 10 were males between the ages of 20 and 76 years.
In the U.S., reported cases have occurred predominantly in male adolescents and young adults 16 years of age and older, according to the Centers for Disease Control and Prevention (CDC).
Myocarditis generally affects younger people and is very rarely seen among older adults, according to Husain, although no possible explanation for this has been established yet, he said.
In Israel, most patients who experienced heart inflammation spent no more than four days in hospital and 95 per cent of the cases were classified as mild, according to the findings of a study commissioned by the health ministry.
Husain said it is “far safer” to get vaccinated and avoid getting COVID-19, which is riskier both on the lungs and the heart, than the “very, very low risk” of developing myocarditis.
The severity of cases can vary, but almost everyone who gets myocarditis recovers from it, he told Global News.
“To this point, we do not believe there are any long-term effects of this inflammation of the heart that appears to occur.”
Judith Guzman-Cottrill, a pediatric infectious disease specialist at the Oregon Health & Science University, said despite the rare occurrence of events, it is critical that public health officials continue to monitor cases of myocarditis and determine if it is a true vaccine side effect.
Tests and treatment
After the onset of symptoms, a number of tests can be performed to diagnose heart inflammation.
These include an electrocardiogram (ECG), chest X-ray and blood tests.
An echocardiogram, which is an ultrasound, can directly image the heart.
A cardiac magnetic resonance imaging (MRI) scan, which is the most sensitive test compared to the others, can also detect inflammation in the heart and fluid around it.
The majority of the cases that have been reported in Canada have improved “quite rapidly” following the initial presentation, Tam said Friday.
Quite often, many cases go undetected because the symptoms are mild and young people are generally healthy, said Husain.
Most cases can be managed conservatively, he added, with common pain killer medications such as acetaminophen or Tylenol for fever or discomfort. It is important to keep patients hydrated.
However, some individuals with severe symptoms might also require hospitalization and specific treatments are tailored to target the viral cause of the inflammation, Husain said.
“What we tell patients and their families is that most of these people will get better, stabilize ..and only rarely will they progress and need more supportive care in an ICU.”
— With files from Global News’ Crystal Goomansingh and Reuters