Efficacy of Recombinant Influenza Vaccine in Adults 50 Years of Age or Older

Influenza epidemics cause substantial morbidity. The seasonal vaccine, an important control measure, is not completely efficacious. This trial assessed the efficacy of a recombinant seasonal vaccine (made in a cell culture rather than with viruses grown in eggs). Reducing the burden of influenza disease requires improved vaccines, and a recombinant influenza vaccine may contribute to this public-health goal. 1 This vaccine contains recombinant hemagglutinin (HA) proteins produced in a serum-free medium by expres SF+ cells. These cells contain recombinant baculovirus vectors carrying genes that code for HA. The process yields recombinant HA that is genetically identical to the selected influenza strains without extraneous egg proteins, formaldehyde, antibiotics, or preservatives. Influenza viruses are grown in eggs to produce the inactivated influenza vaccine (IIV); these viruses typically contain mutations in the genes that code for HA that may reduce vaccine effectiveness. . . .