Local health experts are bracing for a worse-than-expected flu season, after discovering this year's influenza vaccine protects against fewer than 30 percent of the cases diagnosed in Texas.

"If this vaccine is not working as well as we'd hoped, it has the makings of being one of the worst years for flu," said Dr. R. Doug Hardy, infectious disease specialist at Children's Medical Center Dallas and UT Southwestern Medical Center.

Normally, the vaccine protects against 70 percent to 90 percent of the flu viruses that hit the U.S.

In Texas, this season's vaccine protected against nine of 33 influenza samples – or 27 percent.

The shot was more effective around the U.S., protecting against about 50 percent of the cases analyzed nationally.

Nonetheless, health experts are encouraging people who have not been vaccinated against the flu to get the shot.

WILLIAM DESHAZER/DMN

Dr. Martin Jones, regional medical director for CareNow, said the chain's 19 urgent-care clinics in the Dallas area have treated about 8,000 flu cases this season. On Tuesday, he examined Cheryl Birdwell of Rockwall, who had flu-like symptoms.

"I don't want people to say it's worthless and that they shouldn't have taken the shot in the first place," said Dr. William Sutker, chief of infectious diseases at Baylor University Medical Center at Dallas.

"The shot will lessen the severity of the illness, so that maybe you'll have more of a cough or bronchitis instead of pneumonia."

The ability of a flu vaccine to protect a person depends on the age and health of the person getting the vaccine, and the similarity between the virus strains in the vaccine and those in circulation, according to the U.S. Centers for Disease Control and Prevention.

Flu shots have been a good match in 16 of the last 19 years, the federal agency said.

Since September, laboratory testing of early flu cases in Texas indicated that this year's vaccine did not fully protect against A/Brisbane, the predominant flu strain hitting the state.

"The Brisbane strain evolved from the Wisconsin strain," which is in the vaccine, explained Dr. Wendy Chung, chief epidemiologist for Dallas County Health and Human Services.

"You could expect some degree of cross protection. We just don't know how much."

The flu vaccine changes annually based on international surveillance and scientists' estimates about which types and strains of viruses will circulate in a given year, the CDC said.

The vaccine, which protects against three flu virus strains each year, must be manufactured ahead of the season because millions of doses are needed.

"We're talking about predicting nature and the natural path that a disease will take," Dr. Hardy said. "It's always your best guess. Some years, we're really good."

So this year, health officials in Dallas are watching for signs of a more serious flu outbreak.

School absences have been climbing in recent weeks, as influenza-like illnesses are spreading within the 14 Dallas County school districts that voluntarily report absences to the Dallas County health department.

More than 3,000 absences related to flu-like symptoms were reported to the health department in the week ending Feb. 6.

"We would not be surprised to see more cases of influenza in people who received the vaccine because it is not that good of a match," Dr. Chung said.

Despite questions being raised about the flu vaccine, school officials said they still have faith in its protective effect.

"We'd like the flu vaccine to cover all the viruses," said Mary Kay Hartley, Irving school district's director of health services. "It's been kind of hit and miss."

But she said she felt certain that the students who got the shots were getting a milder case than those who didn't.

Several health officials around Dallas said they were seeing more flu cases than usual this year, though the illness typically peaks in mid-February.

An official at Parkland Memorial Hospital said twice as many patients with flu-like symptoms had been seen in the emergency room, compared with last year.

Since the last week of January, flu symptoms had accounted for 352 emergency cases and 42 hospitalizations, said spokeswoman Charise Thomason.

Dr. Martin Jones, regional medical director for CareNow, a chain of urgent-care clinics, said this flu season was shaping up to be the worst since 2003.

"We've had about 8,000 positive flu cases at our 19 clinics in the Dallas area," he said. "The majority of the patients did not get a flu shot, however."

Early diagnosis allows flu sufferers to be treated with Tamiflu, a drug that must be prescribed by a doctor within 48 hours of the illness' onset.

Flu symptoms include fever, cough, sore throat, runny or stuffy nose, headache, muscle aches and extreme fatigue. Most people recover fully in one to two weeks, though it can be fatal.

The Dallas area recorded its first flu-related pediatric death at Children's Medical Center recently, when a teenager with the flu died after developing a drug-resistant staph infection.

Hospital officials declined to identify the youth, but the Dallas County health department said the patient from Ellis County died about two weeks ago.

Ten children, ranging from 4 months to 14 years, have died from flu-related complications around the country so far this season.

No pediatric deaths have been reported among Dallas County residents so far this year.

Dr. Hardy said the area's recent flu death shows that "the flu is serious enough that a healthy young person can die of its complications. That's reason enough to get a flu shot."

Staff writer Katherine Unmuth contributed to this report.

Despite the possible limitations of this year's flu vaccine, experts say it's worthwhile – and not too late – to get vaccinated. Shots are available from personal physicians and area health agencies.

Dallas County: Dallas County Health & Human Services is offering free flu shots until they run out from 8 a.m. to 4 p.m. Monday through Friday at its offices at 2377 N. Stemmons Freeway in Dallas. For more information, call 214-819-2162 or 214-819-2163 or go to www.dallascounty.org/department/hhservices/SeasonalInfluenza.html.

Collin County: Flu shots are available from 8 to 11 a.m. and 1 to 4 p.m. Monday through Friday at the Collin County McKinney Plaza location, 825 N. McDonald St., Suite 130, McKinney. To reach the Collin County Health Care Services office, call 972-548-5500.

Tarrant County: Flu shots are available at six locations through Tarrant County Public Health. Call 817-321-4700 or go to www.tarrantcounty.com/eHealth

IS IT THE FLU?

Flu: Symptoms are worse than the common cold. Symptoms such as fever, body aches, extreme tiredness and dry cough are more common and intense. Tests that usually must be done within the first few days of an illness can tell whether the person has the flu.

Cold: Usually milder than the flu and more likely to include a runny or stuffy nose. Colds generally do not result in serious health problems, such as pneumonia, bacterial infections or hospitalizations.