CDC counters worries about off-target flu vaccine

Are we heading into flu season with a mismatched flu vaccine? Some influenza experts worry two parts of the four-in-one vaccine might not adequately target the main strains that circulate this year, especially the part that protects against H3N2 viruses. But CDC flu experts disagree. David Wentworth, chief of virology surveillance, tells STAT there has been so much H3N2 illness over the past three winters that there’s a lot of immunity to those viruses. That’s one of the reasons why the experts who selected the strains to go in this winter's vaccine chose the one they did: It should both prompt immune systems to remember the older H3N2 viruses and generate protection against the newer variants. “It’s a good choice,” he insisted. And if H3N2 viruses take a back seat this winter, the H1N1 strain in the vaccine is “an excellent selection,” Wentworth said.