The WHO has just released its predictions for the 2026-2027 flu season

Here are the flu strains health authorities predict could hit hard next season

By Jackie Flynn Mogensen edited by Claire Cameron

The winter flu season isn’t over yet, but global health officials are already preparing for the next one. Last week, the World Health Organization (WHO) announced which strains it is recommending vaccine manufacturers produce shots for to ward off the virus in the coming year.

WHO recommended making shots tailored to fight influenza A subtype H1N1, which is also known as swine flu, H3N2, another subtype of the influenza A virus, and the B/Victoria lineage, which is a type of influenza B virus. Officials also asked scientists to prepare “candidate vaccine viruses” for a form of bird flu, H9N2, in case of a future pandemic.

WHO’s vaccine recommendation is the same as last year. But this flu season, a period that usually begins in October and lasts until the following spring, has been particularly tough. So far, in the United States alone, the virus has caused at least 25 million illnesses and 20,000 deaths, including the deaths of 79 children, according to the US Centers for Disease Control and Prevention. Part of the reason this season has been so severe has been the emergence of a new strain of the virus known as “subclade K,” which appears to be able to avoid some of the current flu vaccine’s protective effect — although the shot may still offer some defense, experts say.

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The WHO also warned that flu viruses that usually only infect animals, including bird flu, have sickened at least 25 people in six countries since last September. “Most of these cases had been exposed to infected animals or to environments contaminated with the influenza virus,” the organization said. And while the WHO is not aware of any human-to-human transmission of such zoonotic flu, it doesn’t hurt to be prepared with vaccines, experts say.

The WHO’s recommendations have come amid speculation about the future of next-generation flu vaccines. In February, the US Food and Drug Administration agreed to review an mRNA flu vaccine made by vaccine maker Moderna, which had used the technology in its mRNA COVID vaccines, after the agency initially refused to do so.

An mRNA flu vaccine, which would work similarly to the COVID vaccines, could be produced more quickly than traditional shots, experts say — which could come in handy if and when new variants like subclade K emerge long after a given year’s flu shot is produced.

US officials also support efforts to create a universal flu vaccine, which, if successful, could offer broad protection against many different strains of the virus.

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