Record levels of flu show that vaccine ineffective

It turns out the rumors were true: This year’s flu shot is indeed less effective than usual.

An unusually resilient strain of influenza called H3N2 has been the predominant assailant this season, and the vaccine rolled out last year was ill-suited to protect against it. Though previous analyses from Canada and Australia on its H3N2 effectiveness lent some non-significant support to suspicions about the shot, a new report from the Centers for Disease Control and Prevention laid all doubt to rest: This season’s vaccine reduced illness caused by H3N2 by only 25 percent.

Still, it’s better to get a shot because it offers some protection, especially against other strains that are just starting to emerge. The vaccine was particularly effective for children ages 6 months to 8 years, reducing their risk of contracting H3N2 by more than half. Overall, however, this season’s vaccine is more than 40 percentage points less effective against H3N2 than it is for H1N1, another flu strain that’s also out there.

Weaker-than-usual vaccine protection is among the reasons this season features record levels of flu. The most recent data show the amount of influenza-like illness currently being reported matches the peak of the 2009 swine flu epidemic.

There were 40,414 deaths in the United States during the third week of 2018, the most recent data available, and 4,064 were from pneumonia or influenza, according to the CDC data. The number for that week is expected to rise as more reports are sent to the agency. The death toll in future weeks is expected to grow even higher because flu activity is still rising.