Despite the availability of a vaccine, a flu epidemic is spreading across the United States, with 11 deaths attributed to the virus reported Wednesday alone in San Diego County, Calif. Image by Terry Schmitt/UPI

Dec. 29 (UPI) -- Laboratory-confirmed cases of contagious flu are on the rise in the United States, with 11 deaths attributed to the virus in San Diego County, Calif., alone.

County health officials said six more deaths were reported this week, as were 3,873 confirmed cases of the illness. At this time in 2016, only four deaths were attributed to the virus, they said Wednesday.


The California Department of Public Health said that as of Dec. 16, the date of its most recent report, it counted 10 deaths in its under-65 population. It added that two or fewer deaths per year are typical at this time of the year.

The flu season, usually about 12 weeks long, may have started earlier than normal, the Centers for Disease Control and Prevention said. The flu has reached epidemic proportions in seven of the 10 regions of the country, Lynnette Brammer, an epidemiologist in the U.S. Centers for Disease Control and Prevention's influenza division, said. No national statistics regarding flu and flu-related deaths have been announced.

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The CDC added that elevated numbers of hospitalizations and positive laboratory tests have been reported in most states. Deaths attributed to several forms of the virus, and deaths in which the flu may have been a contributing factor, are separate issues. Earlier this month, the CDC said between 291,000 and 646,000 people worldwide could be expected to die from seasonal influenza-related respiratory illnesses.

On Thursday, North Carolina's Department of Health and Human Services reported the first death of a child from the flu. The age of the child was not announced. There have been 11 flu-related deaths of adults in the state this year, six of whom were over 65.

Five people this season, all adults, and two aged 81 and 98, died of seasonal flu complications in Dallas County, Texas, the county's health services office said on Thursday. A survey released this week by the Walgreen's pharmacy indicates that Texas leads the country in flu activity, the Dallas Morning News reported.

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A flu vaccine, available at pharmacies and in good supply in the United States, may not offer adequate protection against Type A, subtype H3N2, the influenza virus strain currently circulating in the country, the San Francisco Chronicle reported on Thursday.

H3N2 "tends to be the strain of virus that most impacts the elderly, that causes the most complications, and up until this point the vaccine results have been quite disappointing," said Dr. Randy Bergen, of healthcare company Kaiser Permanente. "Those things make us concerned that we're going to have a lot of sick people."

The increase of expected flu cases is similar to that in Australia, where the H3N2 strain was prevalent. During Australia's flu season, which ended in September, hospital admissions for influenza were twice the normal rate and three times the usual number of deaths were reported.

Some reports, though, indicate that the virus strain in Australia is not identical to the one circulating in the United States, leading to suggestions that the U.S. strain is covered by the available vaccine.

"They [Australia] just had a lot of cases, the most they've had since 2009, which was a pandemic year," Dr. David Relman, an infectious disease specialist at Stanford Health Care, told the San Francisco Chronicle.

The United States is using the same vaccine used in Australia, where it had a success rate of only about 10 percent.