High-dose influenza vaccine was about 8% to 9% more effective than standard dose in older adults.
1. Travel Medicine Podcast 1211, "Influenza Holiday Special," moves from flu history to 2025 vaccine data.
2. Dr. J, an internal medicine doctor, and Dr. Santosh, a pediatric infectious disease doctor and researcher, lead the discussion.
3. The episode asks what has changed in influenza research, surveillance, and vaccine choice this season.
4. The hosts trace influenza's first isolation to 1933 in England, when Wilson Smith, C.H. Andrews, and P.P. Laidlaw studied samples from a flu epidemic.
5. They explain that scientists once blamed Haemophilus influenzae, a bacterium linked with sepsis and meningitis, for flu-like illness.
6. The episode describes porcelain filtration and animal testing, including ferrets, mice, pigs, and monkeys, to prove a viral cause.
7. A ferret infected in a lab sneezed on a scientist, who became sick two days later.
8. The hosts note that ferrets remain a model animal for influenza because their nasal mucosal immunity resembles human responses.
9. They say newspapers reacted optimistically, including the line, "Research men at last have flu and colds on the run."
10. The episode reviews the first inactivated flu vaccine developed at the University of Michigan by Thomas Francis and Jonas Salk with U.S. Army support.
11. They say the vaccine was tested on military recruits before licensing in 1945, and that a 1947 study showed no apparent difference between vaccinated and unvaccinated people.
12. The hosts link that failure to antigenic shift and drift, which made surveillance and annual updates necessary.
13. They list six World Health Organization collaborating centers for influenza surveillance in the United States, China, Australia, the United Kingdom, Japan, and Russia.
14. The episode says CDC FluView had no reported data from September 26th until November 15th, just as cases were rising.
15. They describe the U.S. surveillance system as five categories from 10 data sources, summarized weekly from Sunday through Tuesday afternoon.
16. The hosts say the 2025 to 2026 Canadian data show a mismatch with H3N2 subclade K, the dominant circulating strain.
17. They then discuss a Pfizer-funded New England Journal of Medicine trial in 18,000 adults ages 18 to 64, where an mRNA flu shot reduced lab-confirmed flu by 29%.
18. The episode also summarizes FluUnity HD, including Danflu2 in Denmark, Galflu in Spain, and a pooled analysis of roughly 466,000 older adults showing better outcomes with high-dose vaccine.
19. The tone is conversational, combative at times, and structured like a journal club with history, surveillance, and trial review.
20. Listeners interested in flu vaccines, epidemiology, and public health surveillance will get the most from it, while listeners seeking light holiday content or no vaccine talk may skip it.
