Flu vaccine moderately effective, CDC says

Early estimates from the Centers for Disease Control (CDC) place effectiveness of the seasonal influenza vaccine at 62%.

“This interim estimate indicates moderate effectiveness,” the CDC stated in its recent Morbidity and Mortality Weekly Report. At the same time, vaccination reduced the risk for flu-related medical visits by approximately 60%.

As of January 11, 2013, 24 states and New York City were reporting high levels of influenza-like illness, 16 states were reporting moderate levels, and five states were reporting low levels. By January 4, more than 128 million doses of flu vaccine has been distributed in the United States for the 2012-2013 season, out of an estimated 135 million doses previously expected to be available for the U.S. market, a CDC statement said.

“As this time, some vaccine providers might have exhausted their vaccine supplies. Persons seeking vaccination might have need to call more than one provider to locate vaccine,” the CDC stated.

While the CDC recommends that the annual influenza vaccination efforts continue as long as flu viruses are circulating, the early estimates “underscore that some vaccinated persons will become infected with influenza”, according to MMWR. “Therefore, antiviral medications should be used as recommended for treatment in patients, regardless of vaccination status,” CDC stated.

The early results also highlight the importance of continued efforts to develop more effective vaccines, the CDC added.

For its early estimate -similar to an estimate from a meta-analysis of randomized controlled clinical trial data - the CDC analyzed data from 1,155 adults and children with acute respiratory infection (ARI) from December 3, 2012, through January 2, 2013.