22 September 2020

Chicken eggs – on their way out for flu vax production?

KnowCents Technology

Brewing flu vaccines inside chicken eggs may soon be a thing of the past, with the TGA approving the first ever quadrivalent cell-based influenza vaccine – Seqirus’ Flucelvax Quad – in early September.

Flucelvax Quad was approved by the TGA on 1 September to immunise adults and children aged nine or older against two type A and two type B influenza strains.

The vaccine will be available next year in Australia as a non-NIP vaccine.

“Pricing is TBC. We are in discussions with customers ahead of next year’s flu season,” a spokeswoman from Seqirus said.

Flucelvax was approved by the FDA in 2012 and by the European Commission last year.

Optaflu, a trivalent influenza vaccine, was the first cell-based influenza vaccine to be registered in Australia in 2015; Flucelvax Quad is the first quadrivalent cell-based influenza vaccine to be registered in Australia.

Until now, all Australian influenza vaccines have been manufactured inside embryonated chicken eggs.

This has the disadvantage of being a process that takes about six months. Propagating the flu vaccine inside chicken eggs also introduces mutations through egg adaption, which makes the vaccine slightly less effective against the influenza strain circulating in the community.

The misalignment between the vaccine flu strain and the wild flu strain has made flu vaccines somewhat hit and miss in the past. The effectiveness of influenza vaccines has ranged from 19% in the 2014-2015 season to 60% in the 2010-2011 season in the US, according to Seqirus.

Cell-based influenza vaccines can be manufactured rapidly as they replicate the vaccine inside a cell line derived from dog kidneys (MDCK cells). This makes them handy in the event of an influenza pandemic as production can be scaled up quickly.

Vaccines derived using cells do not introduce mutations into the virus during the propagation process, potentially making them a better match for the wild influenza strain.

However, the effect was a little complicated, Professor Ian Barr, the deputy director of the WHO Collaborating Centre for Reference and Research on Influenza at the Peter Doherty Institute for Infection & Immunity in Melbourne, said.

The H1 component of the flu virus did not mutate much in the egg environment so the use of a cell-based production had little impact when this strain was circulating in the population, he said. However, the H3 component, which was normally responsible for more deaths and more severe epidemics, underwent more genetic changes inside eggs.

“So, if it’s an H1 virus circulating in the population, then those cell-derived vaccines probably won’t perform that much better,” he said. “They might do somewhat better, but not that much better. Whereas with an H3 virus, we would expect to see a significant improvement.”

Professor Barr added that the latest cell-based vaccines had “never seen an egg” so they offered a real alternative for people with concerns about egg allergies.

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