By Ethan Covey
Interim data from the CDC show that the 2023-2024 influenza vaccine is effective at reducing the risk for flu-related medical visits and hospitalizations for children, adolescents and adults (MMWR Morb Mortal Wkly Rep 2024;73[8]:168-174).
“This is the first time that interim VE [vaccine effectiveness] estimates were available from four major networks with patients in 22 U.S. states at the same time,” said Aaron M. Frutos, PhD, an Epidemic Intelligence Service officer with the CDC’s Influenza Division. “This allowed us to estimate VE during the season by age and across a range of illness severity.”
The analysis looked at data from four CDC-affiliated VE networks active in the United States.
The interim estimates show that the effectiveness of the 2023-2024 influenza vaccine is consistent with results from previous years. The effectiveness of the vaccine among children was 59% to 67% in outpatient settings and 52% to 61% against influenza-associated hospitalizations. In adults, the interim effectiveness of the flu shot was 33% to 49% in outpatient settings and 41% to 44% against influenza-associated hospitalizations.
“The results are consistent with estimates from seasons when the vaccine viruses were well matched to circulating viruses,” Dr. Frutos said. “This work provides more evidence that flu vaccination protects against flu-related illness and its potentially serious complications.”
Dr. Frutos noted that the analysis yielded two surprises that may benefit from additional research. The investigators found that protection against influenza B viruses was higher than in previous seasons, and effectiveness was similar among adults, regardless of age.
“We also found that vaccine effectiveness estimates for adults aged 65 and older, a group with higher risk of flu-related complications, were similar to those among adults aged 18 to 64 years,” Dr. Frutos said.
Dr. Frutos reported no relevant financial disclosures.
