Top 5 Takeaways

  1. Bivalent Boosters’ Effectiveness: The study reveals that bivalent mRNA COVID-19 boosters offer significant additional protection against symptomatic SARS-CoV-2 infection, especially for those who had 2 to 4 prior monovalent vaccine doses.
  2. Increased Protection Over Time: The effectiveness of the bivalent booster increases with time since the last monovalent vaccine dose, indicating waning immunity from the monovalent doses.
  3. Study’s Scope: Conducted under the Increasing Community Access to Testing (ICATT) program, the study included 360,626 tests from adults reporting COVID-19 symptoms and without immunocompromising conditions.
  4. Relative Vaccine Effectiveness (rVE): The rVE of a bivalent booster was found to be higher in all age groups, particularly several months after the last monovalent dose.
  5. Public Health Implications: Staying up to date with COVID-19 vaccinations, including receiving a bivalent booster dose when eligible, is crucial for maximizing protection.

Original Article Author and Citation

Corresponding Author

Ruth Link-Gelles,

Suggested Citation

Link-Gelles R, Ciesla AA, Fleming-Dutra KE, et al. Effectiveness of Bivalent mRNA Vaccines in Preventing Symptomatic SARS-CoV-2 Infection — Increasing Community Access to Testing Program, United States, September–November 2022. MMWR Morb Mortal Wkly Rep 2022;71:1526–1530. DOI:


This study assessed the effectiveness of bivalent mRNA COVID-19 vaccines in providing additional protection against symptomatic SARS-CoV-2 infection. Analyzing data from the ICATT program, the study included tests from adults who exhibited COVID-19 symptoms but had no immunocompromising conditions.


The study evaluated 360,626 nucleic acid amplification tests (NAATs) performed at retail pharmacies. It compared vaccine effectiveness (VE) in individuals with at least two monovalent vaccine doses, considering the time elapsed since their most recent monovalent dose.


Findings indicate that bivalent mRNA vaccines, authorized to address reduced effectiveness of monovalent vaccines, significantly increase protection against symptomatic infection. The study highlights the importance of the bivalent booster in restoring protection that wanes after monovalent vaccine doses.


The bivalent mRNA COVID-19 vaccine doses provide significant additional protection against symptomatic SARS-CoV-2 infection, especially as time progresses since the last monovalent dose. This underscores the importance of staying up to date with COVID-19 vaccinations, including boosters.

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