Understanding the Impact of SARS-CoV-2 Variants on Vaccination Efficacy

Written by: Sean Brady
Edited by: Esther Melamed

What does it mean that there are SARS-CoV-2 variants?

We have all patiently waited for the COVID-19 vaccines to begin to roll out. As these efforts become actualized, we are unfortunately facing SARS-CoV-2 genetic variants that could potentially undermine vaccination efforts. Before we dive into the impacts of variants on COVID-19 vaccination efforts, what does it even mean for there to be a SARS-CoV-2 variant? A SARS-CoV-2 genetic variant can be thought of like a kid to the original parent SARS-CoV-2 virus. While the kid has many similarities to the parent, they have small changes that make them a little different¹. It is important to note that these genetic variations are just a natural development in the evolution of the SARS-CoV-2 virus¹. Depending on which part of the genetic code is altered in the new virus compared to the original virus determines whether the virus will be more likely or less likely to infect people and cause milder or more severe disease. Now that we understand the basics of what a SARS-CoV-2 variant is, let’s see how the prevailing SARS-CoV-2 variants may impact the efficacy of current vaccines. 

The impact of SARS-CoV-2 variants on current vaccines

Data are now emerging on vaccine efficacy against new SARS-CoV-2 variants. Current data on vaccine-specific changes to SARS-CoV-2 variants have been collected for the yet to be approved Novavax and J&J vaccines, as well as for the already approved Pfizer and Moderna vaccines. For example, the Novavax vaccine has been found to be over 95.6% effective against the original virus, over 85% effective against the U.K variant, but less than 50% effective against the South African variant². The J&J vaccine was shown to be 72% effective in the United States, 57% effective in South Africa, and 66% effective in Latin American countries³. There is preliminary information that the Moderna and Pfizer vaccines could be efficacious against the emerging SARS-CoV-2 variants from the U.K and South Africa, but it is too early to tell for certain.  Moderna has stated that their vaccine should still be effective against the SARS-CoV-2 variants from the U.K and South Africa. The Moderna data has not been peer-reviewed yet⁶. Pfizer has also stated in a preliminary study that their vaccine appears to be effective against the variants found in the U.K and South Africa SARS-CoV-2 variants⁷. It is important to note that the Pfizer study made use of engineered SARS-CoV-2 variants instead of the ‘real world’ SARS-CoV-2 variants⁷. This means more testing and trials need to be done to be more certain on the levels of efficacy outside of a lab setting⁷. The Pfizer data has not been peer-reviewed yet⁷.

The possible future of COVID-19 vaccines

There are many potential ideas for how we can best engineer vaccines to stay ahead of the curve of future SARS-CoV-2 variants. The overarching idea is that COVID-19 vaccinations could become akin to flu vaccinations, with yearly updates to counter any newly emerging variants⁴. Another approach is to add a 3rd vaccine dose to existing vaccines. For example, Moderna is considering a third dose of its vaccine that is specifically targeted at the currently emerging variants⁵. Other manufacturers are thinking of creating multivalent vaccines that would protect against both the original SARS-CoV-2 virus as well as the variants⁴. 

There are still many unanswered questions regarding the efficacy of vaccines in relation to the emerging genetic variants as well as how vaccine makers will respond to best combat new variants in the future. Only time will tell what the best options will be to help quell the pandemic.

In my next article, I will go into more depth on just how vaccine makers were able to make these first-generation vaccines so quickly and still be highly efficacious to the original SARS-CoV-2 virus.