Concerns over common side effects shouldn't scare you from getting COVID-19 vaccines, doctor says

CBC News has received messages from audience members who've reported a range of reactions to their vaccinations, with some hesitant to return for a second dose. But an infectious disease expert said the end result of protection against COVID-19 is worth the common side effects.

Most non-serious reactions go away after a day, but monitoring for rare complications important

A pharmacist administers a dose of the AstraZeneca-Oxford COVID-19 vaccine in Toronto on April 20. Despite concerns over possible side effects to vaccinations, an infectious diseases physician says possible discomfort is worth the end result of protection against COVID-19. (Evan Mitsui/CBC)

Dr. Sumon Chakrabarti empathizes with other Canadians who have reported common side effects after receiving their COVID-19 vaccines. After his second dose of the Pfizer-BioNTech vaccine, he had a low-grade fever and joint pain.

But Chakrabarti, an infectious diseases physician at Trillium Health Partners in Mississauga, Ont., said the end result of protection against COVID-19 was worth the discomfort.

"I don't want to trivialize the way people feel. I know it's unpleasant," he said. "Just remember that these symptoms go away relatively quickly and in the end, you're going to be immune to COVID."

The federal government categorizes its reports of vaccine reactions as serious and non-serious adverse events. The Public Health Agency of Canada recommends that anyone who experiences an adverse reaction reach out to their health-care provider, who will file a report on their behalf.

CBC News has received messages from audience members who have reported a range of reactions to their inoculations, with some hesitant to return for a second dose. While there is new research that suggests a first dose offers strong immune protection, experts and officials still recommend getting both doses of the two-course vaccines being offered.

Here is a look at the types of reactions some people have experienced, what to do if you experience these side effects and at what point people should seek medical attention.

What side effects to COVID-19 vaccines have been reported?

As of April 23, there have been 4,128 reports of serious and non-serious adverse events out of more than 12 million vaccine doses administered, according to the latest statistics from the federal government. The severity of reported reactions ranges from common side effects to rare but serious complications from vaccines.

The most commonly reported side effects include different types of irritation at the site of the vaccine, followed by headaches, hives, nausea, fatigue and fever, according to the data.

"The interesting thing is all of these symptoms are actually coming from your immune system that is activated from the vaccine, and that's what makes you feel that way," Chakrabarti said.

"Fortunately, from what we've seen, even these ones that can put you in bed for a day, they don't last generally for more than 24, maximum 36, hours and people get better."

Other side effects that have been reported, but in lower numbers, include chills, vomiting, diarrhea, muscle and joint pain and anaphylaxis.

Each of the vaccines approved for use in Canada — Pfizer-BioNTechModernaAstraZeneca-Oxford and Janssen (Johnson & Johnson) — have published product monographs that show possible side effects to their respective vaccines.

WATCH | Does one vaccine have more side effects?

COVID-19: Does one vaccine have more side effects?

1 year ago
Duration 3:10
Infectious disease specialist Dr. Alex Wong answers questions about COVID-19 vaccines, including whether any of the vaccines has more side effects and if vaccines can be mixed.

What's the difference between serious and non-serious side effects?

Chakrabarti said aside from some rare complications, most of the side effects that have been reported are considered non-serious in nature. But even ones that are categorized as serious can range from feeling unwell for about a day to requiring additional medical attention.

"It can vary quite a bit across different people. But again, like I mentioned, these things happen very rarely and for the most part, even in older individuals, they don't last for more than about a day," he said.

"If you're feeling really bad, you can always take an Advil or Tylenol. That will generally help."

What about reports of clots connected to vaccines?

In rare but serious cases, vaccine-induced immune thrombotic thrombocytopenia (VITT) is a possible complication of the AstraZeneca-Oxford vaccine.

The National Advisory Committee on Immunization (NACI) says this rare type of aggressive blood clotting "is most commonly estimated to be between one per 100,000 and one per 250,000 persons vaccinated with the AstraZeneca COVID-19 vaccine," with a mortality rate of about 40 per cent, although more research is needed — and that number is subject to change.

"The aggressive nature of these blood clots is really the concern," said Dr. Menaka Pai, a clinical hematologist at McMaster University and a member of Ontario's COVID-19 science advisory table.

The scientific community believes VITT is driven by antibodies after receiving an adenovirus vector vaccine (like AstraZeneca or Johnson & Johnson's), can result in low platelet counts and is often present in unusual locations like the brain or abdomen, Pai said.

The key is to know that it's happening, said Pai, who is also an associate professor of hematology and thromboembolism. "If these clots aren't treated, they can be very serious. They can be fatal."

When should you seek additional medical attention?

Pai said to watch for the following symptoms between four and 28 days after vaccination that could be a sign of VITT and should prompt people to seek medical attention:

  • Persistent and severe headache.
  • Difficulty moving part of your body.
  • Seizures.
  • Problems with your vision, including blurry vision or double vision.
  • Shortness of breath.
  • Severe chest, back, or abdominal pain.
  • Swelling or colour change in an arm or leg.

"I'm not talking about a brief headache. I'm talking about something that doesn't go away," she said.

A seventh confirmed Canadian case of VITT connected to the AstraZeneca vaccine, of more than 1.1 million doses administered, was reported in Quebec on Saturday; late last month, 54-year-old Francine Boyer died of a cerebral thrombosis in a Montreal hospital after receiving the AstraZeneca shot on April 9.

WATCH | Dr. Zain Chagla talks about rare vaccine-related blood clot death:

Dr. Zain Chagla talks about rare vaccine-related blood clot death

1 year ago
Duration 1:15
Infectious disease specialist puts AstraZeneca vaccine risks and benefits into context after Quebec woman's death.

As for people expressing hesitancy, Pai said it's critical that everyone evaluates their personal situation — including the severity of COVID-19 in their community and risks of contracting the virus — before making an informed decision on whether to take the first vaccine offered or wait for a specific shot.

"When you do get that vaccine, the odds are that you will be fine. It's a rare condition after all," she said.

If you have a question of your own about the pandemic, you can send it to


Benjamin Blum is a producer with based in Toronto. He has also worked as a senior writer with, covering an array of international and domestic issues, and was a member of the CBC Sports digital team with a particular focus on rugby. He holds a master's of journalism from the University of King's College in Halifax. You can contact him at

With files from Adam Miller, Cheryl Brown, Alisha Parchment and The Canadian Press

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