San Francisco Frontiers - Mixed results for Lyme disease vaccine hit Valneva shares

There are currently no approved vaccines to treat Lyme disease -- the world's most common illness spread to infected ticks -- in humans.

The new vaccine candidate "demonstrated more than 70 percent efficacy in preventing Lyme disease in individuals aged five years and above" during a phase 3 clinical trial, the US and French-Austrian companies said in a joint statement.

However, because there were fewer cases of Lyme disease than expected during the study period, the trial did not meet its primary endpoint, they added.

Following the announcement, Valneva's share price plunged more than 38 percent at around noon GMT on the Paris stock exchange, which was otherwise up 0.7 percent.

Prizer said in the statement it remains "confident in the vaccine's potential and is planning submissions to regulatory authorities" in the United States and European Union.

"These results bring us a step closer to our goal of delivering a much-needed vaccine to help protect against Lyme disease," Valneva CEO Thomas Lingelbach added.

The vaccine LB6V, formerly called VLA15, creates antibodies in humans that fight off the bacteria Borrelia burgdorferi, which causes Lyme disease.

The condition is rarely fatal, but people bitten by an infected tick often get a rash and suffer flu-like symptoms including muscle and joint ache, headache, nausea and vomiting.

In some cases, it can also cause neurological problems.

Research in 2022 estimated that more than 14 percent of the global population has had the disease, warning that transmission rates could increase as climate change brings longer, drier summers.

C.Lewis--SFF