What "the flu shot is 40% effective" actually measures
Three surveillance networks put 2025/26 effectiveness between 22% and 45% against a drifted H3N2 virus. The figure is a comparison between vaccinated and unvaccinated people who all got tested.
Next season's flu vaccines are being rebuilt around the H3N2 variant from August
WHO updated all three components for the 2026-2027 northern hemisphere season after subclade K dominated globally, and recommended a new candidate vaccine virus for an H9N2 avian strain.
Winter air pollution studies mostly ignore the viruses circulating at the same time
Two February papers put respiratory virus activity into the models. One finds pollution effects amplified at peak influenza; the other finds them attenuated when rhinovirus is high.
The mystery illness in Panzi was malaria, flu and hunger, a lab investigation confirms
Fourteen months after an undiagnosed febrile outbreak alarmed the world, sequencing and PCR on 108 patients found no novel pathogen — half had falciparum malaria and many had a respiratory co-infection.
The first human H5N5 case ever recorded was fatal, and it came from a backyard flock
A Washington State adult died on 21 November after infection with an avian influenza subtype never before found in a person. Contact tracing found no onward spread. Europe is having a record autumn bird season.
A presidential memo asks why the US schedule covers more diseases than peer countries
The 5 December directive tells HHS and the CDC to compare the American childhood schedule with those of other wealthy nations, using a count of diseases as its benchmark.
An mRNA flu vaccine beat a licensed shot by 34.5% — and made more people feel rough
An 18,476-person phase 3 trial and a small human challenge study landed the same day. Both favour the mRNA vaccine against influenza A; neither settles what it does against influenza B.
CDC counted 109 children with influenza-associated encephalopathy last season
Thirty-seven had the necrotising form, of whom 41% died. Just 16% of vaccine-eligible children with encephalopathy had received that season's flu vaccine. There is no national surveillance for the condition.
The June vaccine advisory agenda was cut in half two days before the meeting
A Federal Register notice on 9 June listed eleven vaccine topics and ten scheduled votes over three days. An amended notice on 24 June listed seven topics, three votes and two days.