From Nature.

The US Food and Drug Administration (FDA) has approved the first seasonal flu vaccine comprised of recombinant proteins, rather than inactivated or weakened virus.

The 16 January approval of Flublok, developed by Protein Sciences Corporation in Meriden, Connecticut, arrives as US emergency rooms are clogged with victims of an early and severe flu season. Thirty states are reporting high levels of flu-like illness this season, and New York state and the city of Boston have declared public health emergencies. Vaccine supplies are dwindling.

Flublok is one of a new wave of flu vaccines intended to make production more nimble. The three influenza hemagglutinin proteins comprising Flublok are made in insect cells rather than in chicken eggs, the classical incubator for seasonal flu vaccine. It is the second egg-free vaccine to be approved by the FDA. In November, the agency approved Flucelvax, made by the Swiss pharmaceutical firm Novartis.

But it has been a long road to approval for Protein Sciences. FDA advisors narrowly rejected the vaccine in 2009, arguing that there was insufficient evidence that the vaccine was safe. Development of Flublok and a related pandemic flu vaccine called Panblok was subsidized by a Biomedical Advanced Research and Development Authority (BARDA) contract awarded in 2009, but then threatened when Emergent BioSolutions of Rockville, Maryland and two other creditors sued Protein Sciences for failing to repay over $11 million in loans. The lawsuit was settled in 2010.

Flublok will be out on the market in full force in time for the 2013-2014 flu season, and limited supplies will be available to help out during the current season.

This article is reproduced with permission from the Nature News Blog. The article was first published on January 17, 2013.