By Preeti N. Malani, MD, MSJA new type of influenza vaccine approved last week by the US Food and Drug Administration (FDA) offers the promise of faster production of flu vaccine. The approach used to make the recombinant vaccine, which does not use eggs or influenza virus, allows production of large quantities of a key protein involved in immunity against influenza.
The new vaccine, called Flublok, was developed by Protein Sciences.
“This approval represents a technological advance in the manufacturing of an influenza vaccine,” said Karen Midthun, MD, director of the FDA’s Center for Biologics Evaluation and Research, in a statement. “The new technology offers the potential for faster start-up of the vaccine manufacturing process in the event of a pandemic, because it is not dependent on an egg supply or on availability of the influenza virus.”
Every year, public health experts review global surveillance and laboratory data to identify the influenza strains most likely to cause illness during the upcoming season. Based on this information, the FDA decides what strains manufacturers should include in influenza vaccines for the US population. In general, the better the match between the vaccine strains and the strains circulating in the community, the more likely the resultant vaccine will offer better protection against influenza. Like traditional egg-based vaccines, Flublok is geared toward these target strains, but because its manufacturing process requires less lead time than traditional vaccines, this may facilitate a better match between vaccine and circulating strains.
Although most flu vaccines are made by growing influenza virus in chicken eggs, the new vaccine is produced using a genetically engineered insect virus (baculovirus) containing genes encoding hemagglutinin (HA), the primary protein involved in immunity against influenza. The virus infects insect cells grown in culture, which then produce large quantities of HA. This baculovirus technology has been used previously in other vaccines.
Because its production does not involve eggs, Flublok presumably will provide a new option for people who have egg allergies. But the ultimate effect of the addition of this vaccine to the influenza prevention armamentarium is unknown. Will the shorter manufacturing timetable (permitting the vaccine to more closely “match” the strains of virus that are circulating) and higher HA content improve vaccine efficacy? What populations might benefit the most from Flublok, which is currently approved for adults aged 18 to 49 years? And how will production costs compare with more traditional methods?
The FDA notes that it will evaluate each season’s version of the new vaccine before use by the public, as it does with all influenza vaccines. “The recombinant HA proteins produced in the baculovirus expression system and included in Flublok will be assessed by the FDA,” the agency said.
For more information about influenza vaccination, see this JAMA Viewpoint by Thomas R. Talbot, MD, MPH, and H. Keipp Talbot, MD, MPH, “Influenza Prevention Update: Examining Common Arguments Against Influenza Vaccination.”
For other influenza-related resources, see:
Flu Vaccine Finder: http://flushot.healthmap.org