Cell-derived flu vaccine strains a better match than eggs, Seqirus analysis finds

Seqirus Holly Springs manufacturing
Seqirus manufactures cell-based flu vaccines at a site in North Carolina. (Seqirus)

Flu vaccine efficacy problems were well documented throughout last year’s harsh season. Now the world’s largest cell-based vaccine producer, Seqirus, has published data showing that viruses derived from cells provided a closer match to circulating strains than those made from eggs over several seasons. 

For the retrospective analysis of 12 seasons, the Seqirus team compared the level of match between H3N2 flu strains derived from cells and eggs each year with the strains that ended up circulating. The company found that viruses made from cells had a better match, and that for more than half of the seasons analyzed, there was “little or no antigenic similarity” between the egg-derived H3N2 virus and the strains that circulated.

Speaking with FiercePharma, Seqirus president Gordon Naylor said egg-based vaccines remain the “backbone of the industry,” and have been “extraordinarily successful in dealing with such a difficult challenge over a very long time.” He said the public should understand that vaccines are the best way to avoid getting the flu. 

Still, Naylor said he believes cell-based vaccines could eventually take over the market based on continued favorable efficacy findings, increased manufacturing scale and support from the medical community. Seqirus plans to ship about 20 million to 25 million cell-based flu vaccines this flu season, and it next year aims to ship 40 million doses globally as it launches the technology in Europe. Naylor said the new data are “powerful” and demonstrate a “consistent” trend. 

Last year, flu vaccine manufacturers shipped 155 million flu vaccine doses to the U.S., according to the CDC. During last year’s flu season, vaccines were 40% effective overall and 25% effective against the H3N2 strain, the agency found. The efficacy number for seniors was lower at 20%.  

Digging into data further, the FDA conducted another analysis based on data from 13 million Medicare beneficiaries. The agency found that Seqirus’ cell-based Flucelvax and Sanofi’s Fluzone High-Dose performed best for seniors. Fluzone High-Dose is an egg-based trivalent flu vaccine with four times more antigen than regular shots. Sanofi also markets Flublok Quadrivalent, a recombinant protein-based vaccine.

In recent remarks, FDA Commissioner Scott Gottlieb talked about the analysis and said the agency is “encouraging steps … to ensure new and existing technologies are scalable so that manufacturers can meet domestic and global demand.” For instance, he said, the FDA is working to facilitate improvement of cell lines to boost yield and reduce cost.