There’s been a lot of questions about what COVID-19 vaccine is “best?”

So which one is best? Answer: The first vaccine available to you. They are all effective and the information below will help explain why we need to consider vaccine effectiveness versus only vaccine efficacy.

It is difficult to compare COVID-19 vaccines when they were developed and tested at different times in the pandemic, in different locations around the world.

When and where a COVID-19 vaccine trial was done affects the efficacy numbers. If a vaccine trial was performed when COVID rates were low so there’s less exposure opportunities, it will have higher efficacy. If a trial was done in a place with high case rates with circulating variants and there is high chance of exposure, efficacy numbers may change.

What is needed is an accurate comparison between the vaccines with real-world data. From real-world data we know that all COVID vaccines are 100% effective at what they are supposed to do – prevent severe COVID-19 and hospitalizations, thus reducing the burden on our healthcare system.

For more information please check out this great video from Vox.

Don’t hesitate. Get the vaccine offered. It will help protect you and others.

Frequently Asked Questions

The following FAQ section has information about vaccine efficacy.

Additional vaccine related FAQ sections – vaccine registration and general vaccine questions about rollout, development, safety and immunity.

Which COVID-19 Vaccine is best?

· The best vaccine for you is the one that is offered. With each shot that goes into an arm, we get closer to the end of the pandemic.
· Efficacy matters but it doesn’t matter the most. What matters most is which vaccine will keep you out of the hospital and alive. And all of them do that.

Aren’t vaccines supposed to prevent me from getting sick?

· There is a spectrum of disease – from no illness/full protection, to death. The best case scenario of a vaccine is that it gives you full protection across the spectrum. But the real purpose of a vaccine is to prevent severe disease, hospitalizations and death, or the far end of the spectrum. And all COVID vaccines do just that.

How is a vaccine’s efficacy determined?

· A vaccine’s efficacy is calculated in large clinic trials, on thousands of participants. Half the participants get the vaccine, half will get placebo. Participants are then sent back to live their lives while researchers track whether or not they get COVID over several months.
· Efficacy rates are also applied to an individual. For example, the Moderna vaccine has a 94% efficacy. This means someone who got the vaccine is 94% less likely to get COVID each time they are exposed to COVID. This does not mean that out of 100 people, 6 will get sick.

Why would I want a vaccine with lower efficacy than another one?

· Vaccine efficacy is misleading – it only refers to that particular vaccine’s trial data, not what might happen in the real world. Each study was done at a different point in the pandemic, with different variants in different countries.
· Moderna’s trial took place entirely within the United states between August and November, when case rates were low and variants of concern weren’t spreading. The Johnson and Johnson vaccine was done during the winter, when case rates were highest. It was also done in South Africa and in Brazil, where there were high case rates but also additional variants of concern. Due to the timing and location, there were more chances for COVID exposure during the Johnson and Johnson vaccine trial than during the Moderna trial.

Does the AstraZeneca vaccine cause blood clots?

· Globally, there have been rare incidents of severe blood clots that are currently being investigated. At this time, the National Advisory Committee on Immunization (NACI) has recommended the use of AstraZeneca vaccine in people over 55, and these recommendations may change to include more age groups as the evidence is evaluated.
· Health Canada updated the product monograph—or label—for the AstraZeneca and COVISHIELD COVID-19 vaccines to provide information on very rare reports of blood clots associated with low levels of blood platelets (i.e., thrombocytopenia) following immunization with the AstraZeneca vaccine.
· Health Canada reassures Canadians that the AstraZeneca COVID-19 vaccine continues to be safe and effective at protecting them against COVID-19 and encourages people to get immunized with any of the COVID-19 vaccines that are authorized in Canada.