That could be true, virus' are pretty small critters and can get through some fairly small gaps when motivated. That said, when I wore these masks during the last wildfire here (SOCAL) it cleaned up the air a lot. As I understand the H1N1 virus is dependent on droplets and isn't "in the air". The mask will stop you from inhaling those droplets. . . maybe, I think, not sure but it won't hurt.