To prepare for a potential pandemic of avian influenza caused by H5N1, the Food and Drug Administration approved the first vaccine boosted so its doses can provide stronger immune responses against the flu virus.
Most bird flu viruses do not harm people, but the H5N1 strain may be fatal in up to half of those infected. It likely originated in poultry, and does not transmit effectively from person to person, but if the virus mutates and becomes more infectious, it could spread easily among unprotected populations. In 2007, the FDA started stockpiling the first vaccine against H5N1, to prepare for a possible pandemic. The latest vaccine will be a second vaccine option, and could be helpful if inventory of the immunizations starts to run low, since this version can provide enhanced immunity with a smaller dose.
“This vaccine could be used in the event that the H5N1 avian influenza virus develops the capability to spread efficiently from human to human, resulting in the rapid spread of disease across the globe,” said Dr. Karen Midthun, the director of the FDA’s Center for Biologics Evaluation and Research in a statement. “Vaccines are critical to protecting public health by helping to counter the transmission of influenza disease during a pandemic.”
The vaccine, made by GlaxoSmithKline, is not available for commercial sale or purchase. FDA reviewed studies involving 3,400 people who were vaccinated with the new shot, and compared their responses to another 1,100 who were inoculated with a placebo.