The Changing Face of Influenza Vaccination

The WHO has released its recommendations for the composition of influenza vaccines for the 2025 Southern Hemisphere season. This guidance is based on global influenza surveillance data collected from February to August 2024, which showed varying levels of influenza activity across different regions.

The report highlighted that influenza activity was higher than the same period in 2023, with the Americas experiencing particularly high detections. The most common viruses across most regions were influenza A(H1N1)pdm09 and A(H3N2). In Asia, influenza B/Victoria lineage viruses were prevalent early in the year, followed by a rise in Influenza A detections. In Africa and Oceania, an array of subtypes was observed, each with specific regional patterns of spread.

Based on these trends, the WHO recommends manufacturers prepare the following virus strains for inclusion in the 2025 Southern Hemisphere influenza vaccines:

• Egg-based Vaccines:
  • A/Victoria/4897/2022 (H1N1)pdm09-like virus
  • A/Croatia/10136RV/2023 (H3N2)-like virus
  • B/Austria/1359417/2021 (B/Victoria lineage)-like virus
• Cell Culture-, Recombinant Protein-, or Nucleic Acid-based Vaccines:
  • A/Wisconsin/67/2022 (H1N1)pdm09-like virus
  • A/District of Columbia/27/2023 (H3N2)-like virus
  • B/Austria/1359417/2021 (B/Victoria lineage)-like virus

The recommendations also include a B/Yamagata lineage component for quadrivalent vaccines, although its necessity is questioned because of the absence of B/Yamagata virus detections since March 2020.

Reports suggest the number of US citizens accepting an annual flu vaccination has dropped from 194 million during the 2020-2021 influenza season, to 173 million in 2022-2023. The CDC estimated between 27 million and 54 million illnesses due to the virus, so the FDA has urged a Fall flu shot to help bring these numbers down. However, not everybody is au fait with having needles in their arms at a clinic, so what might the industry do to improve vaccination rates at home?

AstraZeneca offers one option: FluMist, which is now approved by the FDA for home use in children as young as two and adults up to 49 years. As we await further reports on the efficacy – and popularity – of this method, it would be interesting to see the new, similar means of improving vaccination rates generated by the industry.