Health officials say swine flu was widespread in only four states last week, indicating the fall wave of illness is still declining.
Swine flu was widespread in seven states the previous week. Reported infections have been dropping since a peak in late October, when 48 states reported high levels of sickness.
The Centers for Disease Control and Prevention released the new data Thursday. The four states are Delaware, Maine, New Jersey and Virginia.
CDC officials say swine flu vaccine is increasingly easy to get, with more than 118 million doses now available. They say people should still get vaccinated because there could be another wave of infections this winter.