Influenza causes a substantial number of illnesses, hospitalizations, and deaths annually. Although influenza vaccines remain a crucial tool in reducing disease burden, influenza vaccine effectiveness varies seasonally based on the prevalence of influenza virus types and sub-types and the extent to which the vaccines match the circulating viruses, which occurs to varying degrees each year. 

The most common method of manufacturing inactivated influenza vaccines relies on growing the virus in embryonated chicken eggs. This process can result in mutations that cause differences between the strain used in the vaccine and circulating influenza strains. Vaccines that do not rely on egg-based production, including cell culture-based and recombinant vaccines, may induce higher immune responses to circulating influenza strains than egg-based vaccines.

Abt and the Centers for Disease Control and Prevention conducted a randomized, open-label trial to compare immune responses to conventional egg-based vaccines with responses to cell culture-based and recombinant products. The trial was conducted among more than 700 healthcare personnel at two sites in the United States. Study results show marginal immunogenic benefit from the recombinant influenza vaccine compared with conventional egg-based vaccines or cell culture-based vaccines.