In recent weeks, medical institutions in the UK, Canada, and several other countries have witnessed a sharp increase in hospitalizations caused by a new strain of influenza that has become predominant since August 2025. The situation worsens each week, prompting health organizations to issue warnings ahead of the holiday season.
There is a significant rise in influenza cases both in Europe and beyond, with the K subvariant of the influenza A virus (H3N2), dubbed "superflu," being the most prevalent. For instance, in the United States, this strain accounts for nearly 90% of all cases, while in Canada, its share exceeds 70%, leading to a doubling of hospitalizations in the last week.
According to the Centers for Disease Control and Prevention (CDC) in the United States, the number of patients in hospitals is at an abnormally high level for this time of year. The peak of the epidemic has not yet been reached, and healthcare systems are expecting serious challenges in the coming weeks. To date, there have been over 4.6 million reported cases of influenza in the United States, with 49,000 hospitalizations and around 2,000 deaths.
The 2025/2026 flu season began 2-4 weeks earlier than usual. The K subvariant is actively spreading in the USA, Canada, the UK, Norway, as well as in other EU countries, including Kyrgyzstan, Australia, and Japan.
Russia is also facing the dominance of this subvariant of the influenza A virus, referred to as Hong Kong flu.
The virus has undergone several changes at the amino acid level in its hemagglutinin protein, leading to significant genetic differences compared to the vaccine strain. Nevertheless, scientists continue to recommend vaccination.
“If there is a year when you need to get a flu shot, it is now,” said microbiologist and flu vaccine expert Scott Hensley from the University of Pennsylvania.
In light of the ongoing rise in hospitalizations, representatives of medical organizations are strongly urging vaccination and the use of personal protective equipment as the holidays approach.
