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Home » COVID vaccines effectiveness in adults — new CDC report

COVID vaccines effectiveness in adults — new CDC report

A new study from the CDC examined the effectiveness of the COVID-19 vaccines and showed that provided approximately 54% increased protection against symptomatic SARS-CoV-2 infection compared with no receipt of updated vaccine. The vaccines also provided protection against the new JN.1 variant.

I want to quickly review the data from the CDC and summarize what it means for the vaccine.

Photo by Nataliya Vaitkevich on

COVID-19 vaccines effectiveness report

In a paper published on 1 February 2024 in the CDC’s Morbidity and Mortality Weekly Report, Ruth Link-Gelles, Ph.D., of the CDC’s National Center for Immunization and Respiratory Diseases, and colleagues examined 9,222 NAAT (nucleic acid amplification tests, a type of test for COVID-19) COVID test results over the study period among people with COVID-like symptoms. Most people tested were women (61%), about 40% were white, 30% were Hispanic or Latino, and 16% were Black or African American.

Here are the key results:

  • Overall, vaccine effectiveness against symptomatic COVID was 57% for people ages 18 to 49 years and 46% for people ages 50 and older.
  • Vaccine effectiveness was 49% for tests indicating infection with JN.1 lineages, and 60% for tests indicating infection with non-JN.1 lineages.
  • Vaccine effectiveness was 58% among those who received testing 7 to 59 days after receiving the updated vaccine, and 49% among those who received testing 60 to 119 days after receipt.
  • Only 12% of all people tested reported that they had received an updated vaccine dose, and over 26% had never received any COVID vaccine.

The authors concluded that:

All persons aged ≥6 months should receive updated 2023–2024 COVID-19 vaccine. CDC will continue monitoring COVID-19 VE, including against severe disease and for expected waning.


I think some people reading this will say “The vaccine is like a coin flip it only works 50% of the time.” What it means is that if you get the vaccine you have at least a 50% lower chance of contracting a severe disease. Moreover, the updated vaccines reduce the risk of waning immunity which happens with many vaccines as the virus mutates.

The vaccine works, and people should get it.


Michael Simpson

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