Flu Vaccine Effective in More Than Half of Cases, CDC Finds

The influenza vaccine administered last season was effective in 52% of older adults, although the vaccine was not an exact match for the flu strain most prevalent in the United States, according to a CDC study released on Thursday, the Atlanta Journal-Constitution reports (Wahlberg, Atlanta Journal-Constitution, 8/13). For the study, CDC researchers asked 304 Colorado residents who were lab-diagnosed for flu and 1,055 other state residents whether they had received the flu vaccine, became ill or were admitted to the hospital (Yee, AP/San Luis Obispo Tribune, 8/12). The study also found that the flu vaccine prevented pneumonia and influenza in 49% of children younger than age two (Atlanta Journal-Constitution, 8/13).

CDC said that children who previously have never received the flu vaccine should receive two doses because the study found that those who received only one dose had the same protection against flu as children who did not receive the vaccine. According to CDC, the efficacy rate of the flu vaccine last season was comparable to rates in previous seasons when the vaccine was not an exact match for the most prevalent flu strain (AP/San Luis Obispo Tribune, 8/12). Dr. Carolyn Bridges, a medical epidemiologist for the National Immunization Program at CDC, said, "We should continue to vaccinate even when we may not have a perfect match."

According to the Journal-Constitution, no new flu strains have emerged since CDC finalized the vaccine for the next season. Dr. Keiji Fukuda, chief of influenza epidemiology at CDC, said, "It looks like the strains selected for the vaccine will be good for the upcoming year," but he added that new flu strains could emerge (Atlanta Journal-Constitution, 8/13).