How effective are the COVID-19 vaccines, and for how long? - Wassim Saad MD, FRCPC, FACP

Jan 28, 2021

*Please note that this article is currently being updated to reflect the most up to date information. Check back soon for an update.

Is it possible for someone to get the vaccine but still get COVID?

Yes, no vaccine is 100%.  Right now it looks like the antibodies and the immune response to the vaccine lasts at least 90 days. In a recent paper that was published, the levels of protection at 90 days are actually higher than the levels of protection against the virus that are acquired through being infected. So, the vaccine seems to have a little bit of an edge at 90 days. But nobody knows what will happen in the next few months; whether the vaccine will have effective protection afterwards is not clear.

What is the length of time for immunity once someone is vaccinated?

We don’t know. What we do know from the clinical trials that have been done so far, we know for sure that it will last at least 14 weeks. Having said that, we do know from other vaccines and immune system response, and from people who have had natural infections with COVID, that immunity likely lasts anywhere from 6-9 months. But beyond that, we can’t answer because obviously we haven’t had enough time or experience with this vaccine. It’s possible that this vaccine could provide a year or two years, maybe lifelong immunity, although it makes it less likely again, because we’re targeting one single protein, and there’s the possibility of mutations. The immune system is quite complex but, in general, a safe estimate would be 6-9 months.

Further Reading:

Durability of Responses after SARS-CoV-2 mRNA-1273 Vaccination, New England Journal of Medicine, January 7, 2021

Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine, New England Journal of Medicine, December 30, 2020. Updated January 15, 2021.

Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine, New England Journal of Medicine, December 10, 2020. Updated December 16, 2020

About the Expert:

Wassim Saad, MD, FRCPC, FACP is the Vice President of Medical Affairs & Chief of Staff at Windsor Regional Hospital. Dr. Saad completed his undergraduate degree at the University of Windsor before completing his medical degree at the University of Ottawa in 2001. He went on to complete his specialty training in Internal Medicine at the University of Toronto before returning to Windsor to start his clinical practice.

More Resources:

WE-SPARK Health Institute Resource Hub