RSV vaccines for babies and adults are on the way. Here's what the CDC is saying about them.

A federal advisory committee on Thursday discussed promising results of new vaccines and treatments for RSV while raising some concerns about the products that are currently under Food and Drug Administration review.

Respiratory syncytial virus infects nearly everyone by age 2 and typically causes cold symptoms. But it’s also the leading cause of hospitalizations among newborns and younger children, with the Centers for Disease Control and Prevention reporting between 58,000 and 80,000 hospitalizations per year among those under 5.

RSV also strikes at the other end of life: It causes more than 177,000 hospitalizations and 14,000 deaths among older adults every year.

The CDC's Advisory Committee on Immunization Practices on Thursday weighed recommendations for two RSV vaccines for older adults and pregnant people, and a monoclonal antibody for babies and toddlers.

If approved by the FDA later this year, the CDC panel will have an official vote on recommendations followed by the CDC director's approval.

Here's what we know.

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Sanofi’s monoclonal antibody for infants and toddlers

A monoclonal antibody from Sanofi and AstraZeneca, called nirsevimab, helps prevent RSV lower respiratory tract disease in newborns and infants entering or during their first RSV season.

The FDA accepted nirsevimab to review for approval in January. If approved, it would be the second monoclonal antibody on the market for infants. The other option – palivizumab – is only recommended for high-risk infants who were born severely premature at 29 weeks or earlier.

Jon Heinrichs, Sanofi's global head of innovation and emerging sciences, expects the 50-milligram dose of nirsevimab to be available for all infants up to 24 months of age, regardless of whether they were born to term or preterm.

The CDC panel reviewed previous data that found:

  • The monoclonal was about 80% effective against medically attended RSV lower respiratory tract infections in infants born at 35 weeks or later, according to clinical trial data released this week.

  • Nirsevimab reduced the incidence of infections by 70% in healthy preterm infants born between 29 and 35 weeks compared to the placebo, per data released in January.

According to research reviewed by the panel, the antibody would be best for:

  • All babies at birth if born during October through March

  • Babies born during April through September, who should get nirsevimab within eight months of their first RSV season, preferably during their two-, four- or six-month wellness visit

  • High-risk babies entering their second RSV season

The panel expressed a few concerns regarding calling it a vaccine and the cost.

Nirsevimab is not technically a vaccine but panel experts think it should get vaccine perks. This could include monitoring by the Vaccine Adverse Event Reporting System (VAERS), making nirsevimab available at no cost to families through the Vaccines For Children program, and appearing on immunization records.

Heinrichs said the monoclonal antibody will be priced like a vaccine, and cost analysis model from the company put it at $500. Although there is no set price until the product comes to market, panel experts worry nirsevimab may not be cost-effective.

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Pfizer’s RSV vaccine for pregnant people

The FDA announced Wednesday it has agreed to review Pfizer’s vaccine candidate, RSVpreF, for approval and set an action date for August 2023. If approved, the vaccine would be for pregnant people to help protect against RSV severe disease in infants from birth through 6 months.

In the fall, the company said results from a Phase 3 clinical trial showed its vaccine protected infants when given to pregnant participants between 24 and 36 weeks of gestation. Through the first 90 days of a baby's life, the vaccine was more than 80% effective at preventing severe illness. At 6 months, it remained nearly 70% effective. The trial did not raise any major safety concerns for parent or child.

On Thursday, Pfizer revealed new data on maternal and infant safety:

  • Researchers said pregnant people who received the vaccine experienced moderate to mild side effects like redness, swelling and some pain at the injection site, fatigue; and headache, nauseas, muscle or joint pain, vomiting and diarrhea.

  • Of the roughly 7,400 participants who were enrolled in the trial, about 5.6% of infants were born premature, which the CDC says is on par with national preterm birth rates.

A working group for Pfizer's maternal vaccine won't make suggested recommendations until June. But in the meantime, panel experts raised questions regarding breastfeeding and limited data.

The panel wanted to know how breastfeeding played a role in transferring RSV immunity to the infant. And because most of the data reflected pregnant people in their third trimester with term births, panel members also asked for more information on complications specific to pregnancy and birth.

GSK and Pfizer vaccines for older adults

The federal advisory panel also discussed RSV vaccines for older adults developed by GlaxoSmithKline called AReSVi and Pfizer under the same name as the maternal vaccine, RSVpreF.

  • GSK: The vaccine was shown to reduce severe RSV in older adults by 94%, according to a 25,000-person Phase 3 trial.

  • Pfizer: In August, researchers announced a single 120-microgram dose of RSVpreF was effective at preventing severe disease in adults 60 and older in a study of more than 37,000 people.

The big debate surrounding these vaccines was whether to recommend them for adults 60 and older, or 65 and older. Some panel experts argued the vaccines should be recommended to an older population because the risk for severe illness, hospitalization and death tends to increase with age.

But others argued the vaccines should be recommended for people 60 and older to narrow gaps in health equity, as adults from racially diverse and low-income communities tend to suffer the worst outcomes of RSV at earlier ages.

Contributing: Karen Weintraub, USA TODAY. Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

This article originally appeared on USA TODAY: RSV vaccine for babies, adults: What to know about CDC review of data