New research published by the Centers for Disease Control and Prevention (CDC) offers the first real-world data showing how well the updated (bivalent) COVID-19 vaccines work. The updated mRNA shots were designed to target newer strains of the virus and provide better protection from a COVID-19 infection compared to the original (monovalent) vaccine.
The data show the bivalent booster (whether Pfizer or Moderna) is significantly more effective than the original monovalent vaccine at preventing a COVID-19 illness (infection with symptoms) in adults during recent months.
For adults who got their last monovalent dose two to three months prior, the bivalent booster was:
- 30% more effective for people ages 18–49
- 31% more effective for people ages 50–64
- 28% more effective for people ages 65+
For adults who got their last monovalent dose eight or more months prior, the bivalent booster was:
- 56% more effective for people ages 18–49
- 48% more effective for people ages 50–64
- 43% more effective for people ages 65+
People under 18 were not eligible for the updated booster when this study began.
Researchers analyzed data from more than 230,000 people who had been vaccinated with at least two doses of the original monovalent vaccine, and who were tested for COVID-19 between Sept. 14 and Nov. 11. Among all test results (positive AND negative), researchers identified which individuals had received the bivalent vaccine and which ones had not.
The result: People who received the bivalent booster were more likely to test negative.
These new data, which focus on hundreds of thousands of real people, show that the bivalent vaccine does indeed provide additional protection against the currently predominant Omicron strains.
Researchers had suspected the bivalent vaccine would provide better protection against infection as the newer Omicron strains spread around the country, but initially only lab studies were available. A cell’s immune response in a petri dish may not perfectly mimic real-world effects.
CDC plans to release additional data on the effectiveness of the bivalent COVID-19 vaccines soon. Stay tuned for a deeper dive into that research in the next couple of weeks.
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