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A study predicts that this fall's flu vaccine -- a new H3N2 formulation for the first time since 2015 -- will likely have the same reduced efficacy against the dominant circulating strain of influenza A as the vaccine given in 2016 and 2017, due to viral mutations related to vaccine production in eggs.
The method, known as pEpitope (pronounced PEE-epih-tope), was invented more than 10 years ago as a fast, inexpensive way of gauging the effectiveness of proposed flu vaccine formulations. The pEpitope method accounts for 77 percent of what impacts efficacy of the vaccine in humans. It's a computational method that measures critical differences in the genetic sequences of flu strains. In the new study, the method accurately predicted vaccine efficacy rates for more than 40 years of flu records. These included the past two flu seasons in which vaccines offered only limited protection against the most widely circulating strain of influenza A. The latest pEpitope study suggests that pEpitope is a more accurate predictor of vaccine efficacy than long-relied-upon ferret tests, particularly for data gathered in the past decade.Image credit: U.S. Air Force photo/Senior Airman Areca T. Wilson
