US CDC backs Pfizer's maternal RSV vaccine to protect infants

By Sriparna Roy and Michael Erman

(Reuters) -The U.S. Centers for Disease Control and Prevention (CDC) on Friday backed Pfizer's respiratory syncytial virus (RSV) vaccine for women in the middle of the third trimester of pregnancy to protect their babies from severe illness.

The CDC recommendation comes after a panel of advisers voted 11 to 1 for use of the shot in women 32 weeks to 36 weeks into their pregnancy from September to January, paving the way for it to become the first maternal vaccine for the seasonal respiratory virus available in the country.

“This is another new tool we can use this fall and winter to help protect lives,” CDC Director Dr. Mandy Cohen said in a statement.

The vaccine was approved by the U.S. Food and Drug Administration last month for use during that same window of 32 to 36 weeks into pregnancy to prevent lower respiratory tract infection and severe disease in infants until they are six months old.

"RSV throughout my career has been a difficult disease with just supportive care treatment because there have been no options so today is an exciting day," said Dr. Katherine Poehling, a member of the CDC advisory panel and a professor of pediatrics and epidemiology and prevention at Wake Forest School of Medicine.

Getting the vaccine late in pregnancy is likely to reduce a possible risk of preterm births and complications that might arise from taking it earlier, doctors on the panel said.

RSV is a common respiratory virus that usually causes mild, cold-like symptoms but can also lead to serious illness and hospitalization. It is typically a seasonal illness, starting in autumn and peaking in the winter in most of the U.S., according to the CDC.

Because RSV is a seasonal disease, "year round administration could not benefit children born in April through September," panel member Dr. Sarah Long, professor of pediatrics at Drexel University College of Medicine said.

If needed, those babies could receive Sanofi and AstraZeneca's antibody therapy nirsevimab to prevent RSV in infants and toddlers, which was approved earlier this year, she said.

An estimated 58,000 to 80,000 children below the age of five years are hospitalized each year due to RSV infection in the U.S., according to government data.

Pfizer's vaccine, along with another made by GSK, won U.S. approval in May for use in people age 60 and older and are already available around the country.

Pfizer said the list price of the maternal shot will be $295 per dose, the same as for older adults. It plans to use a tiered pricing strategy for the shot outside of the U.S.

At an advisory meeting in May, FDA staffers had flagged a higher number of pre-term births among participants taking Pfizer's vaccine in a clinical trial compared to those who received a placebo. However, the agency said the difference did not appear to be statistically significant, thus might have been due to chance.

A surge in cases of RSV infections coinciding with an increase in COVID transmission and an earlier-than-normal flu season has raised the specter of a so-called 'tripledemic' of respiratory illness across the United States.

CDC has said it expects total hospitalizations from the three to be similar to last year.

For the first time, vaccines to protect against all three diseases will be available this autumn, the government health agency said.

(Reporting by Sriparna Roy and Mariam Sunny in Bengaluru; Editing by Bill Berkrot)