New Study Suggests Flu Vaccination Likely to Have a Substantial Public Health Impact, Prevent Millions of Medical Visits

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December 13, 2023 — A new study published in The Journal of Infectious Diseases estimates that flu vaccination reduced the risk of flu-related emergency department and urgent care (ED/UC) visits by almost half and hospitalizations by more than a third among U.S. adults during the 2022-2023 season. CDC recommends that everyone 6 months and older get a seasonal flu vaccine each year. With flu activity increasing in most parts of the country, now is still a good time to get vaccinated.

The 2022-2023 flu season saw unusually early and intense flu activity, with high hospitalization rates and co-circulation of other respiratory viruses, including SARS-CoV-2 and respiratory syncytial virus (RSV). In this analysis, which looked at more than 100,000 acute respiratory illness-related health care encounters between October 2022 and March 2023, flu vaccination reduced the risk of influenza A-associated hospitalizations by 35% and ED/UC visits by 44%, with vaccine effectiveness varying by age group and care setting as follows:

Hospitalization

  • People 18-64 years who were vaccinated were 23% less likely to be hospitalized with flu.
  • People 65 years and older who were vaccinated were 41% less likely to be hospitalized with flu.
  • Similar vaccine effectiveness (VE) was also observed among hospitalized groups of people who are at higher risk for severe complications from flu, including:
    • older adults
    • those with immunocompromising conditions
    • those with multiple underlying chronic medical conditions

Emergency Department or Urgent Care

  • VE against ED/UC encounters was similar among people 18-64 years (45%) and 65 years and older (41%)
  • VE against ED/UC encounters was also similar among those without and with immunocompromising conditions (44% and 38%, respectively).

Most influenza virus infections were caused by influenza A(H3N2) viruses well-matched to the vaccine. Even in seasons with moderate vaccine effectiveness like the 2022-2023 season, flu vaccination is likely to prevent millions of flu-related medical visits, tens of thousands of hospitalizations, and thousands of deaths.

Data for this study were collected by the VISION Vaccine Effectiveness (VE) Network, a research collaboration between CDC, Westat, and multiple sites (Kaiser Permanente Northern California, Intermountain Healthcare in Utah, and HealthPartners in Minnesota and Wisconsin) with integrated clinical, laboratory, and vaccination records. The network looks at how well seasonal flu and COVID-19 vaccines are protecting people against moderate-to-severe illness.

Getting an annual flu vaccine is the best way to protect yourself and your loved ones from flu. Vaccination is particularly important for people at higher risk for serious flu-related complications. Find a flu vaccine at vaccines.gov.

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