The FDA has approved a new version of an influenza vaccine called Flublok that will protect against four strains of the virus.

Approved in 2013, trivalent Flublok is the only influenza vaccine on the market fashioned through recombinant DNA technology. The manufacturer isolates a hemagglutinin (HA) protein found on the surface of a naturally occurring flu virus that, as an antigen, triggers an immune response. These HA proteins are combined with portions of another virus, and the mix is grown in insect cells. The HA protein is then harvested and purified.

The Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention recommended trivalent Flublok in 2013 as a vaccine alternative for individuals who have an egg allergy. The two other current ways of making flu vaccines involve eggs. In egg-based manufacturing, inactivated or live attenuated vaccine viruses are grown in eggs. In the cell-based process, vaccine viruses first are grown in eggs and then combined with mammalian cells to replicate. Vaccine antigen is purified from this mix.

In a news release, Protein Sciences called Flublok Quadrivalent a “good choice” for seniors and individuals with compromised immune systems because it contains three times more active ingredient than other quadrivalent flu vaccines, compensating for a weaker immune response.

A clinical study of 9000 adults 50 years of age and older showed that individuals who received Flublok Quadrivalent were more than 40% less likely to come down with a confirmed case of influenza than those who received Fluarix Quadrivalent (Glaxo SmithKline), according to the manufacturer.

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