ALBANYFlu vaccines may prove ineffective when scientists fail to anticipate how the virus may mutate, according to a study published last Thursday. Currently, scientists develop vaccines based on the dominant strain at the end of the previous flu season. However, an analysis of 209 residents across New York state found the dominant virus may change through exposure with other strains, rendering vaccines ineffective. The study conducted by The Institutes of Genome Research with the state Health Department’s Wadsworth Center was published in the journal Nature and also posted online earlier this month on the journal’s Web site. A new, unanticipated dominant flu virus emerges when two strains are exposed to each other, said Elodie Ghedin, the study’s lead researcher at Maryland-based TIGR. That can happen when an individual is simultaneously infected with more than one virus. The new virus may then ultimately become the dominant strain, she said. “It happens every few years that the virus strain doesn’t match (the vaccine), and we’ve never really been sure why,” said Jill Taylor, deputy director of the Wadsworth Center and the center’s lead researcher. “The beauty of this study is that it gives us a reason,” she said. The 2003-04 flu season is an example of a year when the flu virus had mutated so that the vaccine was useless, Ghedin said. As a result, many people who had been vaccinated ultimately became sick. “You have to look at the minor strain because that may ultimately determine what becomes the dominant strain. It’s important to know what’s co-circulating in any given season when you’re developing a vaccine,” she said. The study is part of a U.S. project being funded by the National Institutes of Health.