While the H1N1 flu pandemic seems to have peaked in Butler County, there is a chance for more illnesses through March.

Dr. Tom McGill, Butler Memorial Hospital's vice president of quality and safety and an infectious disease control specialist, said it is likely another wave of influenza will sweep through the region before April.

The H1N1 pandemic began in April 2009 in Mexico and spread globally. The federal Centers for Disease Control and Prevention in Atlanta, estimate there have been about 55 million cases in the United States of the flu from H1N1 with the majority of those affecting people ages 18 to 64.

The CDC also estimates there have been about 11,690 deaths in the U.S. from the H1N1 influenza.

In Butler County, only one person has died directly from a confirmed H1N1 infection. As of the end of October, the Butler Memorial laboratory confirmed 565 cases of H1N1 influenza. That is the most current data on confirmed H1N1 cases here.

The Pennsylvania Department of Health lists the total number of confirmed H1N1 cases statewide at 10,960 with another 130 case probable as of Feb. 11. There have been 77 deaths statewide.

Once H1N1 was identified last April, world health organizations rushed to begin production of a vaccine that would complement the annual seasonal flu vaccine.

McGill said about 70 million people in the U.S. have been vaccinated or been infected with H1N1 giving about 40 percent of the population immunity. However, a 75 percent immunity rate, known as herd immunity, is needed to end the pandemic.

McGill, along with the CDC, the state Department of Health and other health organizations still recommend the H1N1 vaccine for anyone who has yet to get the shot or the flu, especially since it can lead to future immunity.

"Older and middle aged people have not gotten the H1N1 flu as much as younger age groups," McGill said. He attributes those lower numbers to their exposure in the 1950s, probably 1957, when influenza, while not H1N1, had a swine origin.

"That exposure was enough to allow some immunity to this flu, so getting the H1N1 vaccine now may help immunity in the future," he said.