U.S. expert panel backs Pfizer's RSV vaccine for older adults

A panel of outside advisers to the U.S. health regulator on Tuesday recommended Pfizer's respiratory syncytial virus (RSV) vaccine, bringing it closer to becoming one of the first approved RSV shots for older adults in the United States.

The U.S. Food and Drug Administration's (FDA) advisory committee voted 7-4 in favour of the vaccine, saying data from the company's study established that the shot was effective and safe in preventing lower respiratory tract disease caused by RSV in those aged 60 years and older. One member abstained during voting.

GSK, another forerunner in a crowded race to develop the first RSV vaccine, will face scrutiny from a panel of experts on Wednesday.

While panellists backed Pfizer's vaccine, concerns were voiced over insufficient efficacy data in the company's study for adults aged 80 and above, who need the vaccine the most, and suggested a need for detailed post-marketing safety surveillance to address the issue of any serious adverse event.

"The population where the vaccine is going to potentially have the biggest impact is less represented in this study," said Hana Sahly, one of the 12 FDA panellists.

Decision on approval expected by May

The first approved vaccines for the virus — which leads to 3.4 million hospitalizations and 100,000 deaths worldwide each year — could help the firms gain a foothold in a market estimated at $5 billion to $10 billion US, according to analysts.

The FDA is scheduled to decide on approval of the vaccines for people aged 60 and above by May, and typically follows the recommendations of its independent panel of experts.

That would enable the shots to be rolled out ahead of a seasonal surge typical in the winter.

RSV infections can feel like a mild cold, but the virus is also one of the leading causes of more serious health conditions, including bronchiolitis and pneumonia, in young children.

It has also confounded researchers since the search for a vaccine began in the 1960s, but increased understanding of RSV's biology in recent years has led to the development of several shots.

Merck, Moderna, and Johnson & Johnson are also conducting trials of their own RSV vaccines.

High efficacy in trials

"RSV is the last of the great big respiratory viruses that afflict our population on an annual basis," said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center in Nashville.

GSK's vaccine was nearly 83 per cent effective in preventing lower respiratory tract disease in people aged 60 and over, and roughly 94 per cent effective in preventing severe disease.

Meanwhile, Pfizer's vaccine was close to 67 per cent effective in preventing RSV-related lower respiratory tract illness with over two symptoms, and 86 per cent effective against illness marked by over three symptoms.

As for when the shots may be approved in Canada, there's no clear timeframe just yet, though as one report suggests, Health Canada does tend to take longer to approve new products than its counterparts south of the border or in Europe.