Influenza Vaccination Not Effective Against New Flu Strains

As the number of flu cases increases throughout the nation, U.S. health officials are reporting that this season's influenza vaccine is proving not as effective as originally expected. According to the Centers for Disease Control and Prevention (CDC), two strains of the virus infecting the majority of people nationwide were not included in the three strains that make up this flu season's vaccine.

To date, the "Brisbane" and "Yamagata" strains have caused more than 40 percent of flu cases in the U.S. The CDC estimates that the vaccine may only be about 50 percent effective against the two, compared to 70 to 90 percent effectiveness against the "Wisconsin" and "Victoria" strains included in the vaccine.

Public health director Thomas Schlenker, MD, says the news doesn't surprise him, since the influenza virus can mutate into new strains. "You try to match the vaccine with the viral strains predicted to be out there," Schlenker said, "but it's never a perfect match, because it's unpredictable what kind of flu bug individuals are going to get."

"Most years, the prediction is very good," said Joseph S. Bresee, MD, chief of epidemiology and prevention at the CDC Influenza Division. "In 16 of the last 19 years, we have had a well-matched vaccine."

The CDC is also reporting that a new strain of flu has developed a resistance to the popular antiviral drug, TamiFlu.

Despite these problems, the CDC maintains that everyone should still get vaccinated.

"Getting a flu vaccine may reduce the risk of death or hospitalization from the disease," Bresee told WebMD Medical News. "While vaccination is the best way to prevent flu, good hand hygiene and flu etiquette are also effective in preventing flu transmission."

According to Bresee, this year's flu season hasn't peaked yet. He anticipates several more weeks of empty desks at work and school.


Source: Nurses World Magazine