How Effective are the Third & Fourth COVID Doses?

New data from the Centers for Disease Control (CDC) point to third and fourth doses offering protection against illness from COVID-19's BA.5 variant. We look at the numbers in this post. 

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For adults with healthy immune systems, a third and fourth COVID-19 vaccine dose can offer substantial protection against the evolution of Omicron in early 2022, according to a new MMWR. 

In conjunction with other data, the findings of this study showed people infected with BA.2 may also have antibodies that can protect against illness from BA.5. Vaccines may also help protect them against serious illness due to the BA.5 variant. 

Experts reviewed VISION Network data on more than 214,000 emergency department/urgent care visits and more than 58,000 hospitalizations due to a COVID-19-like diagnosis of illness in 10 U.S. states from mid-December 2021 through mid-June 2022. The study revealed:

  • When BA.1 was the predominant variant, vaccine effectiveness (VE) was 61 percent for two doses against COVID-19-associated hospitalizations. VE increased to between 85 percent and 92 percent after people received a third/booster dose. 
  • When BA.2/BA.2.12.1 became predominant, vaccine effectiveness with two doses was 24% against hospitalizations related to COVID-19. This increased to 52 percent to 69 percent after a third/booster dose. 
  • Data indicated similar patterns for visits to emergency departments and urgent care, with lower VE when the predominant variants were BA.2/BA.2.12.1 and higher VE with 3 or 4 doses compared to VE with 2 doses. 
  • For adults ages 50 and older during BA.2/BA.2.12.1, VE against hospitalization related to COVID-19 was 55% more than 4 months after a booster/third dose and increased to 80% more than a week after the fourth dose. 

Our single most important tool to protect ourselves and others against serious illness, hospitalization and death continues to be COVID-19 vaccines. Keep in mind that getting vaccinated now will not prevent you from getting an authorized variant-specific vaccine in the fall or winter when governments will likely open up eligibility to more populations. 

With the BA.5 variant leading to recent increases in hospitalizations and deaths, everyone should ensure their recommended COVID-19 vaccinations are up to date, including additional booster doses for adults over 50 and those who are moderately to severely immunocompromised.

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To learn more about safe travel or to schedule your Covid-19 test prior to traveling, contact a COVID Travel Test location near you.

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