Top 5 Takeaways:

  1. Bivalent mRNA Vaccine Effectiveness: The study found that bivalent mRNA vaccines are effective in preventing COVID-19–associated emergency department/urgent care encounters and hospitalizations among immunocompetent adults.
  2. Comparative Analysis: The vaccine’s effectiveness was compared with both unvaccinated individuals and those who had only received monovalent mRNA vaccines.
  3. Protection Rates: The effectiveness against COVID-19–associated ED/UC encounters was 56% compared to no vaccination, and varied from 31% to 50% compared to monovalent vaccination, depending on the time since the last dose.
  4. Hospitalization Prevention: For preventing hospitalizations, the effectiveness was 57% compared to no vaccination, and varied from 38% to 45% compared to monovalent vaccination.
  5. Recommendations: The study supports the recommendation for all eligible individuals to stay up-to-date with COVID-19 vaccinations, including receiving a bivalent booster dose.

Original Article Author and Citation

Corresponding Author

Mark W. Tenforde,

Suggested Citation

Tenforde MW, Weber ZA, Natarajan K, et al. Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19–Associated Emergency Department or Urgent Care Encounters and Hospitalizations Among Immunocompetent Adults — VISION Network, Nine States, September–November 2022. MMWR Morb Mortal Wkly Rep 2022;71:1616–1624. DOI:


This MMWR article presents an evaluation of the effectiveness of bivalent mRNA COVID-19 vaccines in preventing medically attended COVID-19 cases among immunocompetent adults. It covers a period when the Omicron BA.5 sublineage was predominant in the U.S.


The study utilized data from the VISION Network, analyzing emergency department/urgent care encounters and hospitalizations for COVID-19–like illness. Vaccine effectiveness was assessed among adults who received a bivalent booster dose compared to those unvaccinated or vaccinated with monovalent mRNA vaccines only.


The study found that bivalent vaccines offered significant protection against COVID-19 compared to no vaccination and additional protection compared to monovalent vaccination. The research highlights the importance of staying current with COVID-19 vaccinations, including the bivalent booster.


The findings underscore the effectiveness of bivalent mRNA vaccines in reducing COVID-19–associated medical encounters among adults. They support ongoing vaccination efforts, especially with the bivalent booster, and suggest the need for continued public health measures to combat respiratory illnesses.


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