Pfizer Lyme vaccine shows more than 70% efficacy but misses key statistical goal

Pfizer and Valneva said on Monday their Lyme disease vaccine showed more than 70% efficacy in a late-stage study, even as it missed its main goal

Pfizer and Valneva said on Monday their Lyme disease vaccine showed more than 70% efficacy in a late-stage study, even as it missed its main goal.

U.S.-listed shares of the French drugmaker tumbled more than 35% in premarket trading following the update, while Pfizer was flat.

The vaccine demonstrated 73.2% efficacy starting 28 days after the fourth dose in reducing confirmed Lyme disease cases, compared to the placebo.

However, fewer-than-anticipated Lyme cases during the study led to the trial falling short of the key requirement that the vaccine should still be at least 20% effective even in the worst-case scenario. In the first analysis, it came in lower, at 15.8%.

A second planned analysis met the bar, though with 74.8% efficacy, adding to Pfizer’s confidence “in the vaccine’s potential,” as it plans “submissions to regulatory authorities.”