CDC: This season's flu shot nearly 50% effective

Feb. 20 (UPI) -- Getting the flu shot helped Americans stay healthy this winter season, even though it failed to work against some strains of the virus, preliminary numbers from the U.S. Centers for Disease Control and Prevention suggest.

Early effectiveness estimates released by the agency Thursday indicate that the flu vaccine developed for 2019-20 reduced doctor visits associated with the virus by 45 percent overall, and by 55 percent in children.

These figures are consistent with estimates of flu vaccine effectiveness from past seasons, which typically range from 40 percent to 60 percent, the CDC report noted.

"These numbers show that the vaccine isn't perfect but is helping those who get it," Tony Moody, an associate professor of pediatric infectious diseases and immunology at Duke University Medical Center, told UPI. "So it is having an impact, though not as large an impact as we would like. It's certainly still worth getting vaccinated if people have not yet had the vaccine."

The preliminary findings are based on data from more than 4,000 children and adults who participate in the U.S. Vaccine Effectiveness Network. It includes information on their flu status from October 23 through January 25.

According to data from the CDC, the 2019-20 vaccine has been far more effective than last year's shot, which reduced doctor visits associated with the flu by just 29 percent. Although the final figures won't be released until flu season is over, the vaccine is currently on track to be the most effective shot since the winter 2015-16 vaccine, which reduced doctor visits by 48 percent.

"For the foreseeable future, we're going to have continued year-to-year variation, although the ability to now do whole genome sequencing of viruses should allow slightly better estimation of what will be circulating in the coming year," said Richard T. Ellison, a professor of infectious diseases and immunology at the University of Massachusetts Medical School in Worcester. "There is ongoing research to develop a universal flu vaccine that would target portions of the influenza virus that doesn't change every year, but such vaccines are a number of years away from being available for use."

In the meantime, Moody noted that efficacy of the current vaccine in children is important, given that younger people have been particularly susceptible this season. The CDC estimates that more than 200,000 children 4 years old and younger have been hospitalized with flu-related illness so far this winter, and 92 have died.

"Children have these periodic seasons of higher disease activity, and if the vaccine can help them all the better," Moody explained. "This is probably a 'glass half full' view, but the truth is no vaccine data is going to be perfect, just as no other medical intervention is going to have perfect data."