Puzelli S, Facchini M, Spagnolo D, De Marco MA, Calzoletti L, Zanetti A, Fumagalli R, Tanzi ML, Cassone A, Rezza G, Donatelli I. Transmission of hemagglutinin D222G mutant strain of pandemic (H1N1) 2009 virus. Emerg Infect Dis 2010;16(5):863-5.