Scientists at St. Jude Children’s Research Hospital have identified a mutation that would enable the influenza virus to become resistant to a promising new class of drugs.

The most advanced of these drugs are now in late stage clinical trials, and would represent the first new approved class of influenza therapeutics in nearly 20 years. Identifying and monitoring for resistance will be critical to understanding their effectiveness. These findings also offer clues to synthesizing new compounds with a higher barrier to virus resistance.

Even though vaccines are available, influenza infection still impacts millions of people annually. Influenza drugs are an important second line of defense, but there is only a single class available. The virus can develop resistance to these existing drugs, known as neuraminidase inhibitors. The most widely known are Tamiflu and Relenza.