Doctors urge vaccination after Colorado sets back-to-back records for kids’ flu hospitalizations

Last year, the H3N2 strain of influenza A, which tends to be more severe, was the most common version of the virus, said Suchitra Rao, an infectious-disease specialist at Children’s Hospital Colorado [and professor of pediatrics]. In addition, the strain picked up a few mutations that made the vaccine less effective, and the vaccination rate dropped, meaning fewer kids had even partial protection, she said.