By Michael Erman and Raghav Mahobe

(Reuters) -A panel of advisers to the U.S. Centers for Disease Control and Prevention (CDC) on Wednesday recommended that new vaccines from Pfizer and GSK to prevent severe respiratory syncytial virus (RSV) infections be available to older adults in the U.S. but stopped short of saying all of them should get the shots.

In two separate votes, the CDC's Advisory Committee on Immunization Practices (ACIP) said that people aged 60 and older may receive the RSV shots after consulting with a health care provider.

It was not the strongest recommendation that the ACIP could have made for the shots. Some of the committee members wanted a broader recommendation, but others had concerns that there was not enough data about how effective the vaccines are in people over the age of 75 and other high-risk groups.

"Those who are at high risk for disease and for high risk for hospitalizations and death were actually not included in the trials," said committee member Dr. Helen Keipp Talbot. "The patient population that participated in the study were younger and healthier and had fewer comorbid conditions, were not immunocompromised and were not living in nursing homes."

The CDC's director needs to sign off on the recommendation before the vaccines can be made available. Both drugmakers have said they expect to be able to supply the shots ahead of the RSV season later this year.

RSV usually causes mild, cold-like symptoms but can also lead to serious illness and hospitalization. It is estimated to be responsible for 14,000 deaths in adults aged 65 and older in the United States annually, according to government data.

During the meeting, the companies presented data on whether one inoculation could remain effective over the course of two RSV seasons compared with protection seen with an annual shot.

The efficacy of Pfizer's vaccine in preventing lower respiratory tract disease with three or more symptoms fell to 78.6% through the middle of a second RSV season from 88.9% at the end of the first season in older adults. Efficacy fell to 48.9% from about 65% for less severe forms of the disease in that age group.

With the GSK vaccine, efficacy in preventing severe disease defined by three or more symptoms fell to 84.6% through the middle of the second RSV season, from about 94% at the end of first in older adults. Efficacy of the vaccine in preventing lower respiratory tract disease fell to 77.3% from 82.6% at the end of the first season in older adults.

The U.S. Food and Drug Administration last month approved the first RSV vaccine from GSK, branded as Arexvy, and later Pfizer's Abrysvo for people aged 60 and older to protect them from lower respiratory tract disease caused by the virus.

Pfizer and GSK have said they expect RSV vaccines to eventually become multibillion-dollar sellers.

For this year, GSK has said it expects the U.S. market to be in the range of 10 million to 15 million people, a fraction of the size of the expected flu or COVID-19 market for 2023.

At the meeting, GSK said it expects to price its shot between $200 and $295 a dose. Pfizer provided the CDC with a price range of $180 to $270 per dose but would not guarantee that its final price would fall within that range, saying it was in the middle of competitive price negotiations on the shots.

(Reporting by Michael Erman in New Jersey and Raghav Mahobe in Bengaluru, Additional reporting by Mariam Sunny in Bengaluru; Editing by Bill Berkrot and Lisa Shumaker)