Ask an expert: Get to know the COVID-19 vaccines

I have heard that the two new vaccines that are now available in Canada are a new type of vaccine that uses mRNA. What does that mean?

In general, vaccines work by teaching the immune system to recognize a specific virus or bacteria to help the body fight off future infection. In the case of virus vaccines, they usually contain an inactivated virus or a piece of the virus that can’t cause an infection.

The difference with mRNA vaccines is that they don’t contain an inactive virus or a piece of a virus. Instead, they contain part of the virus’ genetic code, called messenger RNA (mRNA). This code is like an instruction manual our cells then use to build a piece of a virus. In the case of COVID-19 vaccines they build a spike protein found on the outside of the virus. If you are later exposed to COVID-19 and the virus enters your body, your immune system recognizes this invader and is ready to fight the infection.

How well do these vaccines work?

Both vaccines currently available in Canada, the Pfizer-BioNTech and the Moderna vaccines went through clinical trials to gather data on how well they work in preventing COVID-19 infection and to look for any potential safety concerns. These trials each had 30,000 individuals participate. Results showed both vaccines are 94 to 95 per cent effective in preventing COVID-19 infection and there were no serious safety concerns.

Reading about the results of these clinical trials and then the approval of the vaccines was the highlight of 2020. For me, it represents hope, and it feels like the beginning of a turning point in this pandemic. The only way we were going to end this pandemic in a timely way was with a vaccine. We need vaccines to protect ourselves, our loved ones, our colleagues, our patients and other at-risk and vulnerable people from COVID-19. These vaccines are safe and provide a high level of protection against infection.

What about side effects?

Both the Moderna and Pfizer-BioNTech vaccines may cause mild to moderate side effects, like pain at the site of the injection, chills, tiredness or fever lasting about one or two days. These side effects are not unusual for vaccines and are not harmful to our health. With the COVID-19 vaccines, these side effects may be more common after the second dose.

Rarely, vaccines may cause a serious allergic reaction. The vaccine is not recommended for people who are allergic to any of the ingredients of the vaccine. Anyone who has had allergic reaction to any vaccine in the past will need to talk to their doctor about whether they can have the COVID-19 vaccine.

How did the pharmaceutical companies develop these new vaccines and bring them to market so quickly? Can we be sure that they are safe?

The COVID-19 pandemic is a global public health emergency. Governments and businesses have responded very quickly with funding for vaccine development. Scientists from around the world have worked collaboratively, sharing knowledge to advance this work. Then when the vaccines were ready for clinical trials, tens of thousands of individuals quickly volunteered. This entire process has truly been an incredible achievement.

The vaccines have gone through a rigorous scientific review by Health Canada. All vaccines approved for use in Canada have to meet strict safety, efficacy and quality standards. As the vaccine rolls out, Health Canada and the pharmaceutical companies will monitor for any safety concerns.

When will the vaccines enable us to get back to ‘normal’ so we can eat in restaurants, go to concerts and stop wearing masks everywhere?

Vaccines are going to be essential to ending this pandemic but it’s not an overnight solution. Over the next several months it’s going to be crucial for as many people as possible to be vaccinated. We also need everyone, including those who have already been vaccinated, to continue to follow public health advice, practicing physical distancing and wearing masks in public places, even as we see the number of new cases start to go down. This is necessary because although we know that a person who is vaccinated is well protected against COVID-19, we don’t yet have evidence on whether people who have been vaccinated could still spread COVID-19 even if they don’t experience symptoms or become ill. We also need to understand more about the effectiveness of vaccines on the emerging variants and we need to learn more about how long immunity from the vaccine lasts. Scientists and public health experts are going to carefully monitor the data and we will get answers to these questions.

As more and more people are vaccinated, reopening and returning to a sense of normalcy will happen but it’s going to require a gradual and cautious approach.