Lyme Vaccine Shows Promise, but 'Tricky' Path Lies Ahead

A potential comeback for a Lyme disease vaccine just cleared a big, but not decisive, hurdle. Pfizer and French drugmaker Valneva say their experimental shot cut Lyme infections by more than 70% in a late-stage trial of 9,400 people ages 5 and up—strong enough that they plan to seek regulatory approval, reports the Washington Post. However, STAT News sees a "tricky regulatory path" ahead. One reason is that too few participants in the study contracted Lyme disease for the results to be considered conclusive, explains the Wall Street Journal. Still, the real-world effectiveness looked strong at 73.2%, when compared with a placebo.

The new shot resembles LYMErix, a vaccine approved in 1998 that was shown to be about 76% effective but was withdrawn four years later amid safety concerns and weak demand. Since then, the need has not gone away: Lyme, spread by ticks carrying Borrelia burgdorferi, is estimated to strike about 476,000 people a year in the US, and it can lead to long-term problems such as arthritis and heart inflammation if not treated early. One University of Pennsylvania researcher tells the Post that because the vaccine is somewhat similar to the first one, he is "quite skeptical of its regulatory success."