US CDC advisers weigh use of GSK, Pfizer RSV vaccines in older adults

(Adds details on Pfizer and GSK vaccines long-term efficacy data in paragraphs 4-6) June 21 (Reuters) - A panel of advisers to the U.S. Centers for Disease Control and Prevention (CDC) on Wednesday are expected to vote on whether to recommend the use of recently approved vaccines from Pfizer and GSK to prevent severe respiratory syncytial virus (RSV) infections in older adults.

(Adds details on Pfizer and GSK vaccines long-term efficacy data in paragraphs 4-6) June 21 (Reuters) -

A panel of advisers to the U.S. Centers for Disease Control and Prevention (CDC) on Wednesday are expected to vote on whether to recommend the use of recently approved vaccines from Pfizer and GSK to prevent severe respiratory syncytial virus (RSV) infections in older adults. If the CDC's Advisory Committee on Immunization Practices backs the vaccines and the agency's director formally signs off on their use as expected, the shots can be rolled out ahead of the RSV season this fall. The expert panel is expected to discuss exactly who should receive the vaccines as well as how frequently.

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.