A study conducted by American and Canadian researchers has confirmed that flu viruses can build up a resistance to the two currently approved classes of antiviral drugs in several ways and that resistance has risen over the last three years.
The study, which will be published in the Journal of Infectious Diseases in January, showed the analysis of 28 seasonal H1N1 influenza viruses from 2008 to 2010 that were resistant to both M2 blockers and neuraminidase inhibitors, according to Health Day News.
Research also showed that a previously single-resistant influenza virus can rapidly develop into a multi-resistant strain through drug response, mutation or gene exchange with another virus. The percent of dual resistant viruses increased from 0.06 percent in 2007-08 to 28 percent in 2009-10.
“Because only two classes of antiviral agents are approved, the detection of viruses with resistance to drugs in both classes is concerning,” Dr. Larisa Gubareva, a U.S. Centers for Disease Control and Prevention scientist and the study's author, said, according to Health Day News. “If circulation of these viruses with dual resistance becomes more widespread among any of the predominant circulating influenza A viruses, treatment options will be extremely limited. New antiviral agents and strategies for antiviral therapy are likely to be necessary in the future.”