In unvaccinated children , cumulative incidence of infection was estimated to be 59 % in the first wave of H1N1pdm09 in 2009-2010 , and 7 % , 14 % , 20 % , and 31 % in subsequent epidemics of H3N2 ( 2010 ) , H1N1pdm09 ( 2011 ) , B ( 2012 ) , and H3N2 ( 2012 ) , respectively .