The Advisory Committee on Immunization Practices (ACIP) voted today, 13 to 0, in favor of recommending FluBlok during the 2013-2014 influenza season for vaccination of persons 18 through 49 years of age with egg allergy of any severity.
FluBlok is an influenza virus vaccine that is produced by expressing the influenza virus hemagglutinin (HA) protein in insect cells using a baculovirus vector. Baculoviruses are rod-shaped viruses (see photograph) that infect insects and other arthropods. The baculovirus virion contains a double-stranded DNA genome. To express the influenza virus HA proteins, recombinant baculoviruses are produced in which DNA encoding the HA protein is inserted into the baculovirus DNA genome. When insect cells are infected with the recombinant baculoviruses, the influenza HA protein is produced.
To manufacture FluBlok, three recombinant baculoviruses were isolated that contain the HA gene from A/Panama/2007/99 (H3N2), A/New Caledonia/20/99 (H1N1), and B/Hong Kong/330/2001. After infection of insect cells with these recombinant baculoviruses, the HA proteins were purified to greater than 95% purity. In a randomized, placebo-controlled clinical trial, FluBlok was shown to be 44.6% effective in preventing culture-confirmed influenza. The low efficacy might in part be due to antigenic mismatch between the HA proteins used in the vaccine and circulating viruses.
Because FluBlok is not produced in eggs it may be used in individuals with egg allergies. Another alternative for such individuals is Flucelvax, an influenza vaccine produced in cell culture, which was approved by the Food and Drug Administration in November 2012.