As Ontario makes all individuals six months of age or older eligible to receive the monovalent COVID-19 vaccine, new evidence is showing an extraordinarily low number of adverse events following immunization.

A new report published by Public Health Ontario earlier this month showed that Ontario has administered more than 38 million doses of COVID-19 vaccine since 2020, with adverse events reported on 23,002 occasions. That would correspond with an incidence rate of just 0.06 per cent.

However, Public Health Ontario says that approximately 94.5 per cent of these events were not considered serious, with allergic skin reactions, rashes and pain or redness at the injection site among the most commonly reported issues.

PHO said that there were 1,256 events that met its definition for a “serious” adverse effect following immunization.

Of those reports, 1,218 required admission to a hospital and 38 resulted in death.

It should, however, be noted that those events included “any untoward medical occurrences that followed immunization” and are not necessarily proof of “a causal relationship with the vaccine” on their own, PHO said.

“Public Health Ontario looked at 40 million doses of the vaccine that have been given and it (the data) reinforced that these are among the safest therapies that we have in all of modern medicine,” Dr. Fahad Razak, an internist at St. Michael's Hospital, told CP24 on Monday. “These vaccines have been intensely studied, we know they are effective and now we know they are incredibly safe.”

The most commonly reported “serious” adverse event following immunization was myocarditis or pericarditis with a total of 821 reports, or roughly 22.2 incidents per one million doses of vaccine administered.

PHO said that the highest reporting rate was observed in males between the ages of 18 and 24 following a second dose (201.7 events per million doses administered).

The latest research comes as the province widens the eligibility for the new COVID-19 vaccine, which is specifically targeted to combat the now dominant XBB.1.5 subvariant.

Razak said that it is important that Ontarians ensure they are up to date on their COVID-19 vaccinations, especially given a virus that continues to mutate.

He said that he is hopeful the research will be helpful in convincing some people who may be “reluctant due to safety concerns” to get vaccinated.

“The goal here is to keep the (hospital) system protected. Remember this is the system that not only treats COVID-19 and influenza but it is the system that has to treat you if you have a heart attack or are in a car accident or need cancer therapy,” he said. “So I really want people to do what they can do to protect the system. Protect individuals who are at high risk but also our common resource of hospitals, making sure we are able to function as well as we can to take care of you.”

PHO says that the number of serious adverse health events reported following COVID-19 immunization works out to about 3.3 per 100,000 doses.