World ‘not yet prepared enough’ as H5N1 avian flu strain keeps spreading, WHO official warns

The world’s leading influenza experts met this week to discuss the threat posed to humans by the H5N1 bird flu strain that has caused record bird deaths worldwide in recent months.

A group of scientists, regulators and vaccine manufacturers meet twice a year to decide which seasonal flu strains will be included in the vaccine for the coming winter, in this case for the northern hemisphere.

It is also an opportunity to discuss the risk of animal viruses spreading to humans and causing a pandemic. At this week’s meeting, H5N1 clade 2.3.4.4b is the main topic, the World Health Organization (WHO) and global flu experts told Reuters.

“We are better prepared (than COVID-19), but even though we are better prepared, we are not ready yet,” said Sylvie Briand, WHO’s director for global infectious disease preparedness, before the meeting. “We must continue our efforts against the flu pandemic.”

Briand in a briefing after the meeting said the increase in bird and mammal cases was “worrying” and that the agency was working with Cambodia after two confirmed human H5N1 cases were found in one family there.

They are trying to determine whether the family members contracted the virus through the environment — such as exposure to birds or other mammals — or if there was human-to-human transmission.

The threat to humans remains low, officials said

Pathologists have assumed that the virus must mutate in order to infect humans.

Experts have been tracking H5N1 clade 2.3.4.4b since it emerged in 2020 and the latest reports of mass deaths in infected mammals from seals to bears, as well as potential mammal-to-mammal transmission at a Spanish mink farm last year, have raised concerns. .

However, there have been few human cases, and the WHO currently assesses the threat to humans as low.

“This is a natural experiment in front of us, and I don’t think we are comfortable with it,” said Nicola Lewis, director of the WHO Collaborating Center on Influenza at the Crick Institute in London. Speaking ahead of the meeting, he said it would include an assessment of the situation around the world.

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Experts discuss vaccines, virus strains

Experts are also discussing the development of a potential vaccine.

Laboratories associated with the WHO already have two strains of flu viruses related to the H5N1 virus circulating, which vaccine manufacturers can use to make human vaccines if needed. One was added after the previous WHO flu meeting in September 2022, and experts decided at this week’s meeting to add another subtype that better matches the spread of the virus among animals.

Some companies that produce seasonal flu vaccines may also make pandemic flu vaccines. For example, GSK and CSL Seqirus have collaborated with the United States Biomedical Advanced Research and Development Authority (BARDA) to test a shot based on one of the related strains.

Having the strain ready could save about two months on developing a vaccine, said the WHO’s Briand.

But getting enough vaccines developed quickly will remain a challenge in a pandemic situation, experts say.