Flu virus mutates, vaccinated patients still at risk

DALLAS -- Fourteen-year old Avery Schroeder caught it first. She then gave the flu to her 11-year-old sister Ella, over Thanksgiving break.

Both had been vaccinated.

"The flu vaccine that we got in October," explains Baylor Dallas Dr. Bradley Jones, "may not cover about 50 percent of the strains that we're being exposed to."

Dr. Jones says he's also treated a vaccinated flu patient this season.

The flu vaccine is needed after the flu virus has mutated.

More previously vaccinated patients, say CDC officials, are likely to be diagnosed with influenza in coming weeks. A health advisory issued by the CDC warns that could lead to a potentially severe flu season.

According to the CDC, the type A H3N2 strain circulating right now mutated from what was going around a few months ago.

That means the formulation in this year's influenza vaccine isn't a perfect match, though health officials say it still offers protection from the virus.

"It would decrease the severity of the flu if you caught the flu," says Dallas County Health and Human Services Dr. Christopher Perkins. "[It could] prevent you from being hospitalized and ultimately having bad consequences, especially if you have underlying health issues."

Dr. Perkins hopes people don't mistakenly believe they don't need to get a flu shot. The quadrivalent shot protects against three strains in addition to the H3N2.

Dallas County is giving free flu shots to residents who qualify.

H3N2 is a potentially more serious strain, with higher rates of complications. The CDC is urging anyone with underlying medical issues who develops flu symptoms to see a doctor. Anti-viral medication can help prevent serious complications, including pneumonia, which commonly leads to hospitalizations.

The Dallas county health department confirms one person this week already died from influenza.

Dr. Brad Jones from Baylor Health Center explains why flu vaccines may not be as effective this year.