The number of confirmed flu cases more than doubled in the single week ending Jan. 4, with a large percentage of those people requiring hospitalization, according to the Allegheny County Health Department.
The number of lab-confirmed cases surged from 44 to 110 that week, with an average age of 45 years among those flu victims, said health department spokesman Guillermo Cole. Of those cases, 42 people had to be hospitalized, he said. One person, a 62-year-old woman, has died.
"It just reflects the trajectory of the outbreak -- it's on its way up," Mr. Cole said of the pace of the increase. "It peaks, and when it peaks is not known."
Peaks often happen in late January or early February, with flu viruses continuing to circulate into April, making it still possible to ward off influenza later in the season, he said.
"The first line of defense is the flu shot and there's plenty of vaccine," although it usually takes about two weeks to become fully effective, he said.
This year's vaccine is well-matched to the variant of H1N1 swine flu that is causing most of the illness this year, health officials have said. That particular strain of the flu, which emerged for the first time in 2009, is related to a version of swine flu that caused an outbreak in the Fort Dix, N.J., area in 1976 and that shares a similar structure with the virus that caused the Spanish Flu epidemic in 1918-19.
This time last year, when the flu season was particularly severe and started earlier than this year, the county had seen 336 confirmed cases of flu, he said.
State reports, which show suspected as well as confirmed influenza cases, showed similar increases. In the week ending Jan. 4, the overall number of cases in Allegheny County jumped from 149 to 302, according to data from the Pennsylvania Department of Health.
Across the state, the department reported 3,800 confirmed and suspected cases of influenza as of Jan. 4, according to the most recent data reports. Six Pennsylvanians have died as a result of complications from influenza, state officials said.
Amy McConnell Schaarsmith: firstname.lastname@example.org or 412-263-1719.