U.S. Swine Flu Infections Reach the Million Mark

Madeline Ellis, June 26, 2009

Health officials now estimate that as many as 1 million Americans have been infected with the H1N1 flu, which first surfaced in Mexico in mid-April, and the virus shows no signs of abating. Dr. Daniel Jernigan, a medical epidemiologist with the CDC’s Influenza Division, says the novel virus continues to spread in parts of the country, especially the Northeast, even though flu season is normally over by now. “The U.S. will likely see (swine) flu activity continue throughout the summer,” he said during a press conference.

The estimate, based on a mathematical model of surveys by health officials, was presented to a vaccine advisory panel by Lyn Finelli, a flu surveillance official with the U.S. Centers for Disease Control and Prevention (CDC). And while some at the meeting may have been surprised by the number, experts like Dr. William Schaffner, Vanderbilt University’s infectious disease expert, who have been closely monitoring the virus weren’t. “We knew diagnosed cases were just the tip of the iceberg,” he said.

So far, approximately half the H1N1cases worldwide, nearly 28,000, have been reported in the U.S., according to the Associated Press. That count includes 3,065 hospitalizations and 127 deaths. And though infections continue to produce mild illness, for the most part, the percentage of cases hospitalized has been increasing. Finelli says that could be due to closer scrutiny of extremely ill patients. In most cases, other health conditions have also been a factor in hospitalization: about one in three had asthma, 16 percent diabetes, 12 percent immune system problems, and 11 percent chronic heart disease.

By comparison, seasonal flu sickens an estimated 15 million to 60 million Americans each year, leading to roughly 36,000 deaths; usually proving most lethal to the very young and the elderly. The H1N1 has also proven fatal to people 65 and older, with deaths in more than 2 percent of elderly people infected, Finelli said. However, about half of the deaths worldwide were young and previously healthy people. The average age of H1N1 patients is 12, the average age of hospitalized patients is 20, and a mere 37 for those who died.

Both seasonal and swine flu vaccines were another topic of discussion at the meeting. Dr. Anthony Fiore, a CDC flu specialist, said about 10 million doses of seasonal flu vaccine should be available by early September, with the total production for the entire flu season around the 143 million doses produced for the 2008-09 season. The swine flu vaccine has to tested and licensed before it’s distributed to the public, and might be given as two shots, 21 days apart. Health officials outlined possibilities for a campaign compelling people to get the protective vaccination.

Meanwhile, health officials worldwide continue to closely monitor the H1N1 flu virus as it makes its way from the Northern to the Southern Hemisphere, where the flu season is currently under way. Experts fear that, as the virus circulates around the globe, it could mutate—becoming more virulent. Margaret Chan, director general of the World Health Organization (WHO) says the virus is “highly unpredictable,” but “is not mutating at the moment.”