A single peer-reviewed study sequenced all eight genome segments of 30 selected H1N1 samples from Iran. Viruses from two influenza seasons remained genetically close to the corresponding vaccine strains, with changes concentrated in immune-recognition regions. The small genomic sample supports surveillance of circulating viruses; protection estimates derived from sequences were not measured vaccine outcomes in patients.
Researchers at Tehran University of Medical Sciences compared 30 selected influenza A(H1N1) virus genomes with the corresponding vaccine strains. The single peer-reviewed study found average similarity of 99.13 per cent in the 2023–2024 season and 98.78 per cent in 2024–2025. These figures describe genetic sequences, with seasonal changes in viruses that remained closely related to the vaccine strains.[1]
Iran’s National Influenza Center received the samples from people experiencing influenza-like illness. The centre monitors viruses circulating in the country. Oxford Nanopore sequencing covered all eight genome segments; earlier Iranian surveillance had concentrated mainly on two surface-protein segments. Evolutionary trees for the segments showed no detected reassortment, the exchange of genome segments between viruses. The small sample may not reflect the epidemic’s full diversity.[1]
The team separately examined immune-recognition regions on haemagglutinin, a protein on the viral surface. Most samples showed their largest number of substitutions in region A. For the region with the greatest divergence, an amino-acid calculation gave an estimated vaccine efficacy ranging from 38.1 per cent to 50.5 per cent. It was a sequence-based estimate, without comparing clinical outcomes between vaccinated patients and those who had no vaccination, or measuring hospital admissions. Functional experiments are needed to clarify the effects of some substitutions.[1]
