Viva la revolución: rethinking influenza a virus antigenic drift.

Rapid antigenic evolution of the influenza A virus hemagglutinin has precluded developing vaccines that provide durable protection. The yearly costs of influenza (circa $10(11) in the USA alone) easily justify investments in better understanding the interaction of influenza with antibodies and other inducible elements of the immune system that potentially limit or circumvent antigenic variation. Here, I summarize exciting new findings that offer the possibility of a quantum improvement in vaccine efficacy, focusing on studies clearly documenting robust neutralizing antibody responses to the conserved stem region of the hemagglutinin.