How Much Does a Booster Shot Protect Against Omicron?

New research is finally coming out about Omicron.

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Omicron cases are finally starting to go down. Omicron has been gripping the world for the past two months. Finally, peer-reviewed literature is coming out to inform us how much our pandemic tools protect us. I reviewed a recent article from the Journal of the American Medical Association where the authors tell us how much our vaccines still protect us.

The paper captures the period when the Omicron variant truly began to surge. The article’s authors reviewed COVID testing data from the United States from December 10, 2021, to January 1, 2022. Each patient had information on the variant the individuals were infected with, their comorbidities, their vaccination status (unvaccinated versus two shots vs two shots with booster), and the vaccine they took. They used this information to create a series of statistical models exploring how one’s vaccination status affected their risk of being infected with Omicron and Delta. Their results were the following.

Overall, being boosted significantly decreased one’s chance of having COVID-19 against Delta and Omicron. When the authors compared boosted individuals to those who were unvaccinated and those who had only received two doses, those who received their booster vaccine were roughly three times less likely to become infected by SARS-CoV-2.

This was approximately the same amount of protection whether individuals received three doses of the Pfizer or Moderna vaccine. So if we were in a room with ten people with a virus risk present, only three people who were boosted would likely test positive, compared to all ten for those without the booster or unvaccinated.

That was for Omicron. Being boosted provides even more protection against the Delta variant, which is still floating around. In that case, boosted individuals are approximately ten times less likely to become infected. So back to our room of ten people, only around one person present would be possible to test positive compared to individuals with two shots.

Getting yet another shot may feel like a nuisance. Fortunately, it is a great way to protect yourself from getting infected. The pandemic will improve this coming Spring and Summer, just like last year. Be sure to do what you can to get yourself there healthy.


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Julian Willett, MD
Julian Willett, MD

M.D. trained in the US, now researching SARS-CoV-2 and COVID-19 in Canada for his Ph.D. After earning my Ph.D., I will be pursuing an Anatomic Pathology residency embracing my path towards being a physician-scientist. My academic interests are directed towards topics that provide the greatest net benefit for the greatest number of people. I love complicated, messy, and poorly understood topics.

I enjoy writing in my spare time, along with 3D printing and staying connected with my family. I have been a longstanding proponent for global health with projects ranging from supporting Doctors without Borders (MSF) to Syrian refugees (Syrian American Medical Society). 

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