Flu Vaccine Effective for Only 9% of Seniors This Season, CDC Finds

While this season's influenza vaccine was effective for about 56% of all recipients of the shot, it was helpful for just 9% of recipients age 65 and older, according to a CDC analysis of the current season's vaccine efficacy rates, Reuters reports (Steenhuysen, Reuters, 2/21).

The analysis -- published in the latest edition of the agency's Morbidity and Mortality Weekly Report -- is based on the U.S. Influenza Vaccine Effectiveness Network poll of 2,697 children and adults, which was conducted between Dec. 3, 2012, and Jan. 19 (Weise, USA Today, 2/21).

CDC officials noted that the vaccine effectiveness rates could change as the end of the season approaches, when more individuals would be sampled (Reuters, 2/21).

According to CDC epidemiologist Michael Jhung, the flu-related hospitalization rate among individuals age 65 and older already has reached a record high this season. The analysis found that in the last week of January, the rate of seniors who were hospitalized with a confirmed case of the flu was 116 per 100,000 individuals in the age group. The previous record high was 73.7 individuals per 100,000 (USA Today, 2/21).

Although CDC researchers did not identify a specific reason for the vaccine's limited effectiveness among seniors, agency scientists noted that virus type, age and variations in immune system response can affect how individuals respond to vaccines (Reuters, 2/21).

Some experts also said that elderly people tend to have a slower immune system response to flu strains of varying strengths, the AP/Sacramento Bee reports. As a result, the majority of them faced great challenges this year against the different, harsher strain of the flu, compared with the weaker strains of the previous two years (Stobbe, AP/Sacramento Bee, 2/21).

CDC Director Thomas Frieden said, "We simply need a better vaccine against influenza, one that works better and lasts longer." Several flu vaccine manufacturers -- including AstraZeneca, GlaxoSmithKline and Sanofi -- already are working to deliver more effective vaccines, some of which could be available by the next flu season, Frieden said. He added that HHS also is working to create a universal flu vaccine within the next eight to 10 years (Reuters, 2/21).

However on Wednesday, NIH Director Francis Collins warned that a federal program to develop a universal flu vaccine would be delayed if mandated spending cuts under sequestration take effect next month (Reichard, CQ Roll Call, 2/20).