Pharmaceutical company Pfizer announced on Thursday positive results in the elderly of its vaccine against respiratory syncytial virus (RSV), for which there is currently no licensed vaccine, AFP reported.

This virus causes bronchiolitis, a respiratory disease that mainly affects infants, but can also be dangerous for the elderly, who can develop pneumonia, for example.

According to US health authorities, more than 177,000 elderly people in the United States are hospitalized each year due to RSV infection, and about 14,000 die from it.

The vaccine has been tested on people over the age of 60 in ongoing clinical trials. According to a preliminary analysis, it was found to be about 85% effective in preventing severe cases (three or more symptoms).

Pfizer said it plans to apply for approval to the US Food and Drug Administration (FDA) and other regulatory bodies around the world “in the coming months.”

“Scientists and researchers have worked unsuccessfully to develop RSV vaccines for more than half a century,” said Annalisa Anderson, scientific coordinator for vaccine development at Pfizer. “These results are an important step in our efforts to protect against RSV.”

The vaccine was well-tolerated and raised no safety concerns, according to the company, which said the results will be submitted for publication in a scientific journal.

About 37,000 participants have already been recruited for the clinical trial, with a total of 40,000 expected. Half of the people receive a vaccine that targets two strains of the virus (RSV A and B), while the rest receive a placebo.

Other companies, including Moderna, are also working on developing an RSV vaccine.