Atlanta, Georgia (CNN) -- As many as 80 million Americans were sickened by and another 16,000 died because of the H1N1 influenza virus between April 2009 and December, the Centers for Disease Control and Prevention said Friday.
Those numbers are at the high end of the CDC's estimate. The number of infected could be closer to 39 million while deaths could be about 8,000.
Exact counts are difficult to obtain because many people with the flu don't seek medical care and only a small number who do are tested.
The H1N1 virus is still circulating and causing illness, hospitalization and death, according to the CDC, which recently made another call for vaccination. About 61 million Americans have been vaccinated.
Vaccines are widely available, with more than 130 million doses produced and 160 million people at high priority for getting the vaccine.