GlaxoSmithKline, Seqirus launch first round of flu shots for upcoming season

Seqirus expects almost half of the total 50 million flu vaccine doses it offers in the U.S. will be cell culture-based Flucelvax Quadrivalent. (Seqirus)

As flu-vaccine heavyweights dispatch their first doses for the upcoming season, they're planning millions more doses made with next-generation production processes rather than traditional egg-based manufacturing.

GlaxoSmithKline and Seqirus have joined Sanofi Pasteur in dispatching their first shipments for the coming U.S. flu season. For the latter two, the plans include a significant boost in their cell culture-based vaccines, which are believed to be better than traditional shots made from eggs.

Seqirus said almost half of the total doses it offers to Americans will be Flucelvax Quadrivalent, thanks to manufacturing updates that have enabled it to boost production. Sanofi also said it will increase supplies of Flublok Quadrivalent and Fluzone High-Dose to 25 million doses.

Recombinant protein-based Flublok is grown in insect cells, while Flucelvax is made in animal cells. Grown in cells, the viruses in those shots don’t go through the genetic mutations seen with traditional egg-based production. Experts believe the egg-based process may be responsible for the relatively low effectiveness of the 2017-18 flu shots.

RELATED: Sanofi ships first of 70M doses of flu shots for the 2018-19 season

In total, Seqirus expects to supply more than 50 million doses, while GSK plans to supply 40-45 million and Sanofi, which started shipping two weeks ago, plans 70 million. GSK's delivery will be the highest volume the British pharma has targeted to date, the company said. Seqirus’ 50 million doses are on par with its plans last year.

Apart from Flucelvax, Seqirus sells egg-based vaccine Afluria Quadrivalent and an adjuvanted vaccine, Fluad, specifically developed for people 65 years and older. While Seqirus bills itself as the largest producer of cell-based flu shots in the U.S., Sanofi’s egg-based Fluzone is still the world's best-selling flu vaccine. For seniors, the French pharma has Fluzone High-Dose, which contains a larger amount of antigen. 

RELATED: GlaxoSmithKline's Fluarix protects young children in large phase 3 test

GSK hopes its own flu shot advancement will translate into more sales. In January, the FDA expanded Fluarix Quadrivalent's reach to include infants and toddlers 6 months and older. Before that, the vaccine was only approved for those 3 years old and above. That came about a year after the other GSK flu shot, FluLaval, was also allowed into that age group.

Amid a serious, H3N2-predominant flu season last year, flu vaccines were 36% effective overall and only 25% effective against the nasty H3N2 strain, a CDC interim analysis showed. In seniors, that number dropped to 18%.

According to an FDA analysis based on data from more than 13 million Medicare beneficiaries, Seqirus’ Flucelvax and Sanofi’s Fluzone High-Dose performed best last season among all seniors, having worked 10.7% and 8.4% better, respectively, at reducing the chance of hospital visits among those 65 and older.