Company compared 12-year data for manufactured and circulating H3N2 flu strains.

In 2017, flu vaccines were found to be just 40% effective overall and only 25% effective against the H3N2 strain. For seniors, that percentage dropped to below 20%. The U.S. Food and Drug Administration also found that, for 13 million Medicare beneficiaries, Flucelvax (Seqrius) and Fluzone High-Dose (Sanofi), both egg-based vaccines (the latter a trivalent flu vaccine with four times more antigen than regular shots), performed the best for seniors.

Seqirus recently reported more results that suggest that vaccines based on virus strains derived from cells perform better than traditional vaccines produced from eggs. The company found that the level of match between H3N2 flu strains that ended up circulating each year was higher for strains derived from cells than those derived from eggs over 12 previous flu seasons. In addition, for more than half of the analyzed seasons, “little or no antigenic similarity” was observed between the egg-derived H3N2 virus and the strains that circulated.

Egg-based viruses still predominate, but Seqirus President Gordon Naylor thinks that cell-based vaccines could eventually take over a significant portion of market share due to their greater efficacy and manufacturing scalability. The company expects to ship 20 to 25 million cell-based flu vaccine doses for the 2018–2019 flu season and 40 million the following year.

The FDA is encouraging the development of scalable technologies for flu vaccine manufacturing to ensure that companies can meet domestic and global demand.