The CDC is reporting the first two cases of “dual mutant” strains of flu in the US. These new variants have evolved much higher resistance to common medications to fight the flu. The new strains are much less responsive to Tamiflu, the most frequently prescribed antiviral medicine. One study estimated that Tamiflu accounted for 99.8% of antivirals prescribed to children for flu. Physicians have also used this medication to treat people infected with Avian flu on dairy farms. Genetic mutations made the virus 16 times less vulnerable to Tamiflu. Other antivirals such as baloxavir marboxil have not lost any of their effectiveness. In addition flu vaccines continue to provide protection against infection and severe illness from the virus. “It is unknown how widely these mutated viruses will circulate in the upcoming season”, the CDC said. “It is important to continue monitoring the spread of these viruses and the evolution of these viruses”.