The Food and Drug Administration has delayed by three months its decision on what could be the first vaccine available in the U.S. for chikungunya virus.
In an announcement Monday, French vaccine maker Valneva said the FDA extended an evaluation of its shot to the end of November. The regulator was expected to decide whether to grant the vaccine an “accelerated” approval by August 31.
However, according to Valneva, the agency needs more time to come to terms with the company on the design of a post-marketing trial first. Such a study is required for drugs that receive an accelerated approval, and is meant to provide further information about a treatment’s purported benefits, risks and best uses.
The FDA hasn’t asked Valneva to submit any new data before approval, the company said.
The announcement delays the arrival of what could be the first marketed shot in the U.S. for the chikungunya virus, which is transmitted to humans by the bites of infected mosquitoes. Infections from the virus can cause fever as well as severe joint and muscle pain that lasts for several days. No preventive treatments are available, though Valneva and Danish drugmaker Bavarian Nordic have shots in advanced testing.
Valneva submitted its experimental shot, dubbed VLA1553, to the FDA in December following success in Phase 3 studies last year. Testing showed a single shot spurred neutralizing antibodies against the virus in most study volunteers after one month, and that the results largely held up after six months. The positive results were observed in younger adults as well as those over 65 years of age. The majority of side effects were mild to moderate.
While the FDA hasn’t required more information before an approval, the delay “may be frustrating for investors, given the likely complexity” of the post-marketing trial the agency is requesting, wrote Stifel analyst Max Herrmann, in a note to investors on Monday.
The delay also pushes back the receipt of a priority review voucher Valneva is expecting upon approval. These vouchers can be used to shorten FDA reviews and are often sold from one company to another. Valneva doesn’t expect the issues it’s facing in the U.S. to impact the shot’s ongoing evaluation in Canada or a planned submission in Europe.
Still, the news represents the latest setback for Valneva, which has seen its shares plummet from more than $60 in 2021 to less than $14 apiece. The company and partner Pfizer recently pushed back their development timeline for an experimental Lyme disease shot. Valneva also struggled with a COVID-19 shot that has faced multiple hurdles in Europe.