The A/Fujian/411/02(H3N2)-like stains from the 2002-2003 season gained a potential glycosylation site at position 144, thereby masking the supposed "key" site for antigenic change [33] . Substitutions at antigenic site B and the predicted N-glycosylation at position 144 in HA antigenic site A together with a stronger NA might have contributed to the increased infectivity of the reassorted Fujian-like viruses of the 2003-2004 season, causing an epidemic in Denmark. We have shown that the preferred antibody epitope for genetic change is antigenic site B for the Danish dataset also reflecting that site A is camouflaged by glycosylation. Thus the antigenic changes at a glycosylated site A may not play a major role in escape from the immune system as long as the glycosylation is present.