WHO holds crucial meetings to decide influenza strains for jab

Experts from the WHO will analyse different samples of influenza that are currently circulating in different global populations before determining the composition of this year’s flu jab for the southern hemisphere.

The World Health Organisation is holding crucial meetings this week to decide which flu strains to vaccinate against for the coming months.

There are four types of influenza virus, two of which primarily infect humans. They are constantly mutating and evolving, meaning scientists and manufacturers have to update their flu vaccines every year.

The WHO’s discussions are expected to run until Friday 24 September, when an announcement will be made publicly.

There had been concerns that scientists would be unsure of which flu strains to incorporate into the latest vaccine due to the low amount of influenza in circulation since the Covid lockdowns and other infection prevention measures were deployed last year.

However, the WHO has insisted that it has enough samples to assess. “It is true influenza is circulating at a very low rate, but we do have samples of what is circulating that have been submitted through the Global Influenza Surveillance and Response System (GISRS),” a spokesperson for the WHO said.

“The strains currently circulating are under discussion at the vaccine composition meeting.”

Dr John McCauley, director of the World Influenza Centre at the Francis Crick Institute, said the “numbers of samples received by the WHO has been lower this year, but the numbers are still sufficient to ask whether new viruses have been seen and whether they are genetically different from those seen previously, for example in early 2020.”

There is a global network of around 160 WHO-recognised labs in roughly 130 countries that carry out flu surveillance. The UK is home to four of these labs, based in London, Belfast, Glasgow and Cardiff.

These laboratories monitor flu activity and identify virus types and subtypes in clinical samples. Some of these labs will replicate newly-detected viruses and share with the six WHO Collaborating Centres for influenza.

Twice a year, once for the Northern Hemisphere jab and then also for the Southern Hemisphere jab, the Collaborating Centres come together to assess all their genetic data and determine what influenza viruses needed to be vaccinated against for the forthcoming flu season.

The new vaccine candidates are made in the WHO Collaborating Centres and then shared with other labs, where they’re further developed to be suitable for mass vaccine production, before being passed to industry manufacturers.

The new vaccines will aim to offer protection against a number of flu viruses deemed to be a threat to humans.

Dr McCauley said that “a good result for vaccine effectiveness would be 60 to 70 per cent – thus reducing flu levels in the community by over half. This is a huge benefit to the healthcare system.”

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