Health
The U.S. Food and Drug Administration has approved Flublok, the first trivalent influenza vaccine made using an insect virus (baculovirus) expression system and recombinant DNA technology.
Flublok is approved for the prevention of seasonal influenza in people 18 through 49 years of age.
Unlike current flu vaccines, Flublok does not use the influenza virus or eggs in its production.
Flublok’s novel manufacturing technology allows for production of large quantities of the influenza virus protein, hemagglutinin (HA) – the active ingredient in all inactivated influenza vaccines that is essential for entry of the virus into cells in the body.
The majority of antibodies that prevent influenza virus infection are directed against HA. While the technology is new to flu vaccine production, it is used to make vaccines that have been approved by the FDA to prevent other infectious diseases.
“This approval represents a technological advance in the manufacturing of an influenza vaccine,” said Karen Midthun, M.D., director of the FDA’s Center for Biologics Evaluation and Research. “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.”
FDA Assistant Secretary Nicole Lurie said the nation has reached “a landmark in influenza vaccine history” with the approval of the new vaccine.
Lurie said the Assistant Secretary for Preparedness and Response’s Biomedical Advanced Research and Development Authority, which began in 2006, partnered with the vaccine’s manufacturer, Protein Sciences Corp. of Meriden, Conn., once the vaccine reached an advanced development stage.
Each year, the FDA, World Health Organization, the Centers for Disease Control and Prevention and other public health experts collaborate on the review of influenza disease surveillance and laboratory data collected from around the world in an effort to identify strains that may cause the most illness in the upcoming season.
Based on that information and on the recommendations of the FDA’s Vaccines and Related Biological Products Advisory Committee, the FDA selects the different influenza strains each year that manufacturers should include in their vaccines for the U.S. population for the upcoming influenza season.
The closer the match between the circulating strains causing disease and the strains in the vaccine, the better the protection against influenza.
Flublok contains three, full-length, recombinant HA proteins to help protect against two influenza virus A strains, H1N1 and H3N2, and one influenza virus B strain.
As it does with all influenza vaccines, the FDA will evaluate Flublok annually prior to use by the public each flu season.
The recombinant HA proteins produced in the baculovirus expression system and included in Flublok will be assessed by the FDA.
The effectiveness of Flublok was evaluated in a study conducted at various sites in the United States that compared the use of Flublok in about 2,300 people to a placebo that was given to a control group of similar size.
Flublok was about 44.6 percent effective against all circulating influenza strains, not just the strains that matched the strains included in the vaccine.
Flublok’s safety evaluation was conducted in a study of about 2,500 people who were vaccinated with Flublok.
The most commonly reported adverse events included pain at the site of injection, headache, fatigue and muscle aches, events also typical for conventional egg-based, inactivated influenza vaccines.
Flublok has a shelf life of 16 weeks from the date of manufacture. Health care providers should check the expiration date before administering Flublok.
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Norwegian pregnant women who received a vaccine against the 2009 H1N1 influenza virus showed no increased risk of pregnancy loss, while pregnant women who experienced influenza during pregnancy had an increased risk of miscarriages and still births, a study has found.
The study suggests that influenza infection may increase the risk of fetal loss.
Scientists at the U.S. National Institutes of Health and the Norwegian Institute of Public Health (NIPH) published their findings online Jan. 17 in the New England Journal of Medicine.
The research was conducted following the H1N1 influenza pandemic that took place between spring 2009 and fall 2010.
The researchers at the NIH were from the National Institute of Environmental Health Sciences (NIEHS).
Norwegian public health officials had urged pregnant women to be vaccinated. However, media reports of pregnancy losses after flu shots caused some expectant mothers to forgo vaccination.
First author Siri Haberg, M.D., Ph.D., of the NIPH and colleagues initiated the study to help address the question of vaccine safety, by taking advantage of Norway’s excellent registries and medical records system.
Haberg spent one year of her postdoctoral fellowship in the NIEHS Epidemiology Branch before returning home to Norway during the pandemic.
NIEHS researcher and co-author Allen Wilcox, M.D., Ph.D., said the NIPH researchers combined data from obstetrical visits, birth records, and vaccination registries to investigate whether the influenza vaccination posed a risk to pregnancy.
The study found that influenza infection increased the risk of fetal loss by up to twofold. Influenza vaccination did not increase the risk of loss. Instead, the results suggest that vaccination reduces the risk of fetal loss.
“Most important is that vaccinations protect pregnant women against influenza illness, which could be harmful for both the mother and the baby,” Wilcox said. “If pregnant women are worried about their fetus, then getting a flu shot is a good thing to do.”
Haberg added, “Pregnant women should find it reassuring that we found no harmful effects on the fetus associated with H1N1 vaccination.”
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