This year’s influenza vaccine has reduced the risk of contracting the virus by approximately 50 percent, according to an interim report released by the Centers for Disease Control and Prevention (CDC). The agency warns that the 2016-17 flu season is likely not over yet, and continues to urge everyone over the age of six months to get vaccinated as soon as possible.
The CDC estimates that the flu vaccine has been 48 percent effective at reducing influenza-associated medical visits so far this flu season. Last year, this number reached 59 percent, however the previous year’s vaccine saw only 19 percent effectiveness.
The flu vaccine is changed each year to confer immunity against which strains are predicted to be predominant in that season. According to the CDC, this year’s vaccine has shown improved protection against the influenza A (H3N2) virus, which was also predominant during the 2014-15 flu season.
The CDC reports that as of November of last year, 37 percent of children between the age of six months and 17 years had received the flu vaccine. The same percentage of adults aged 18 to 64 were vaccinated in this time, with adults over the age of 65 seeing the highest vaccination rate at 57 percent.
“As of February 3, 2017, approximately 145 million doses of influenza vaccine had been distributed in the United States for the 2016–17 season,” wrote the authors of the CDC report. “Because influenza activity remains elevated, CDC and the Advisory Committee on Immunization Practices recommend that annual influenza vaccination efforts continue as long as influenza viruses are circulating.”
This observational study used vaccination data from 3,144 children and adults enrolled in the US Influenza Vaccine Effectiveness Network (US Flu VE Network) to estimate the national effectiveness of the flu vaccine. The authors admit that the results of the report are limited based on the fact that vaccination status was self-reported at four of the five study sites.