A panel of outside advisers to the U.S. health regulator on Wednesday backed GSK Plc's respiratory syncytial virus (RSV) vaccine, setting it up for a race with rival Pfizer to become the first approved U.S. shot against the disease.

The Food and Drug Administration's (FDA) advisory committee voted unanimously in favor of the vaccine, saying the company's clinical study data showed the shot was effective in preventing lower respiratory tract disease caused by RSV in adults aged 60 and above.

The recommendation for GSK's vaccine follows the panel's vote in favor of Pfizer's RSV shot on Tuesday.

Pfizer and GSK are running a tight race to tap into the RSV vaccine market, which is estimated to be over $5 billion and could exceed $10 billion by 2030, according to analysts.

The panel voted 10 to 2 in favor of GSK's vaccine safety when administered to adults aged 60 years and older for the prevention of lower respiratory tract disease caused by the viral infection.

The FDA is scheduled to decide on the vaccine by May, and typically follows the recommendations of its independent panel of experts.

• FDA Panel Recommends Pfizer's RSV Vaccine