Fall and winter is the typical flu season in the US, and officials are seeking the best ways to deal with both swine flu and seasonal flu. Though most cases of swine flu have been mild, there are concerns that severity may spike during the fall and winter due to the cold weather and/or the pandemic influenza pattern of a mild spring outbreak followed by a far more severe fall/winter resurgence. This pattern was most notably observed during the 1918 “Spanish flu” pandemic. If an effective H1N1 swine flu vaccine can be made available by October, officials hope to prevent such a resurgence.

Researchers theorize that the swine flu vaccine may prove to affect individuals differently. Because the present H1N1 swine flu strain bears some resemblance to strains seen several decades ago, older individuals may already have some degree of immunity from past exposure. Younger individuals have likely had no exposure, and may require a higher dosage of the vaccine.