Estimates of present mid-season flu vaccine effectiveness (VE) in Europe and China vary from 32% to 58% general, with larger safety towards influenza B than A, based on three research printed in Eurosurveillance.
32% to 58% safety in Europe
In Europethe 2009 H1N1 influenza A pressure is the predominant flu virus and is circulating together with influenza A(H3N2) and B/Victoria.
Public well being researchers who analyzed eight test-negative research from 17 European nations (5 single- and three multi-country) estimated an interim all-age influenza A VE of 32% to 53% in main care from September 2024 to January 2025. On this setting, it was least efficient amongst kids and adults aged 65 years and older.
In hospitals, VE was 33% to 56%, with some indicators of decrease VE by subtype and better VE towards influenza B (58% or increased in each settings).
In abstract, flu vaccination prevented one third to greater than three quarters of infections in main care or hospitals, however safety diversified by age-group and examine. The vaccine protected a 3rd to over a half of individuals towards influenza A an infection, the principle circulating subtype.
The authors advisable persevering with to advertise vaccination amongst goal teams and strengthening different prevention measures for older adults. They referred to as for end-of-season research with bigger pattern sizes and extra data on virus traits that will assist clarify variations in effectiveness.
42% efficacy in France
Researchers in Francewho reported excessive ranges of flu circulation in Europe beginning in November 2024, performed a test-negative examine utilizing knowledge on 44,420 flu-negative and 15,052 flu-positive folks from greater than 1,600 French neighborhood labs from October 2024 to February 2025.
Preliminary findings for the 2024/25 influenza season spotlight the continued worth of vaccination in lowering influenza burden, with effectiveness various by virus sort and age group.
General VE for all age-groups was 42%, with 26% towards influenza A and 75% towards influenza B. Estimated VE was 60% amongst folks aged 0 to 64 years, falling to 22% amongst these aged 65 and older. VE amongst symptomatic individuals was 41% each for individuals who had respiratory signs and those that had a fever.
Flu vaccine uptake amongst individuals was 6.5% in adults aged 18 to 64 years and 36% in these 65 and older, rising within the general inhabitants from 1.8% in week 44 to 19% in week 52 in 2024 and as much as 52% in older adults.
“Preliminary findings for the 2024/25 influenza season spotlight the continued worth of vaccination in lowering influenza burden, with effectiveness various by virus sort and age group,” the examine authors concluded. “Strengthened public well being efforts to extend vaccine uptake and probably to enhance vaccine formulations stay vital to lowering the affect of seasonal influenza.”
China reviews 49% effectiveness
Chinese language researchers used a test-negative examine design to estimate VE amongst non-hospitalized sufferers in Beijing, the place H1N1 predominated (99.3%), with all 38 sequenced strains clustered in clade 6B.1A.5a.2a and 37 of 38 antigenically much like the vaccine pressure. The examine was based mostly on knowledge from the Influenza Surveillance System in Beijing, which incorporates 40 sentinel hospitals and 19 community labs, from October 2024 to January 2025.
Our examine discovered a reasonable VE (48.5%) towards medically attended laboratory-confirmed influenza, much like the interim discovering of Canada (53%).
A complete of 8,775 sufferers with influenza-like sickness have been recruited, with 76.8% testing detrimental for flu and 23.2% testing constructive. VE towards an infection with any flu virus was 48.5%, whereas it was 48.7% towards H1N1. Vaccination within the present or earlier season towards any flu virus was 52.5% to 54.9% efficient, respectively, in contrast with no vaccination in each seasons.
“Our examine discovered a reasonable VE (48.5%) towards medically attended laboratory-confirmed influenza, much like the interim discovering of Canada (53%),” the authors wrote. “Compared, VE in Beijing was beneath 45% within the earlier three seasons, whereas in Europe, it ranged from 30% to 53%, and in the USA, it diversified between 19% and 48% over the previous 10 seasons.”
They famous that early estimates of flu VE are essential for formulating flu-prevention methods and supporting World Well being Group (WHO) vaccine pressure suggestions.
Final week the WHO introduced its advisory committee’s suggestions on the strains to incorporate for the Northern Hemisphere’s 2025-26 flu season, which change the H3N2 elements however maintain the present 2009 H1N1 and influenza B strains the identical.
The three strains advisable for the trivalent (three-strain) vaccine are additionally the identical as these advisable for the Southern Hemisphere’s 2025 season vaccine, which the group weighed in on at its conferences in September 2024.
