COVID-19 (coronavirus) Featured

The road to a COVID-19 vaccine: Your questions answered

Dr. Rob Kozak

Sunnybrook recently asked our social media followers to send us their questions about COVID-19 vaccine development and research. Dr. Rob Kozak, scientist and clinical microbiologist at Sunnybrook, shares his answers below.

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Why are there so many COVID-19 vaccines in development? Shouldn’t there just be one?

We can’t be certain that one specific vaccine will be efficacious, protective and work in all age groups, or that it will provide long-lasting immunity. There are both pre-clinical and clinical trials that must be successful before we can use a vaccine. By having many candidates in the running, we increase the chances we will have one (or hopefully several) winners.

How fast can a vaccine realistically become available? Isn’t it unsafe to rush?

It’s difficult to say with certainty when a vaccine will be ready. Right now, there are several candidate vaccines that are in the last phase of human testing (Phase III clinical trial), so we will hopefully know by early 2021 if they are protective. I’m optimistic that by next spring we will have several vaccines available.

Rushing the science of developing a vaccine is not a good idea, but there is a balance that can be struck between doing things quickly and not compromising safety. This can include strategies like combining phases of a clinical trial (eg. designing a Phase I/II trial) in order to get more data sooner that can help save time.

What is the process for deciding which vaccine is the one that everyone will use?

Clinical trials can be conducted in different populations (young healthy individuals, the elderly etc.) to determine which vaccine and dose will work best in different groups. A benefit of everyone getting a vaccine is that it will generate herd immunity so that people who can’t get the vaccine (such as those with immunodeficiencies) still benefit from the protection.

Will a vaccine help stop the spread for multiple years or only seasonally?

This will depend mostly on the vaccine and how well it induces immunity, and how well this immunity lasts. If the vaccine induces a really good, protective and long-lasting immune response then there is a good chance it will protect people for multiple years, although a booster shot may be necessary.

How can we trust that the vaccine will be safe long-term?

There is a rigorous testing process that happens before a vaccine gets approved, and safety is a key factor that is examined. Follow-up studies are also conducted on vaccines to look at longer-term effects. The vaccines currently approved for other diseases (e.g. flu, hepatitis B etc.) all have excellent safety profiles, and the same standards will be applied to any COVID-19 vaccine used in Canada.

Is there any chance getting the COVID-19 vaccine could actually give me the virus?

No. The leading vaccine candidates that are in clinical trials only contain parts of the virus, such as a protein from the virus, or a bit of the genome. This is what allows your immune system to get trained to recognize SARS-CoV-2 later if you get infected and keeps you protected from it.