The Centers for Disease Control and Prevention (CDC) estimates that this season’s flu vaccine has been 48 percent effective at preventing flu-related outpatient visits for acute respiratory illness.

More specifically, the vaccine has been 43 percent effective against the influenza A virus (H3N2) and 73 percent effective against the influenza B virus, according to the federal agency’s Interim Estimates of 2016–17 report.

The CDC says flu activity is likely to continue for several more weeks, and vaccination efforts should continue as long as flu viruses are circulating.