Pfizer’s RSVpreF Vaccine Accepted by FDA for Priority Review

Pfizer’s RSV maternal vaccine candidate, RSVpreF (PF-06928316), was recently accepted by the US Food and Drug Administration (FDA) for priority review, with an action date set for August 2023.[0] The FDA’s decision sets the stage for the potential approval of the first vaccine to be administered to pregnant individuals to protect against the complications of respiratory syncytial virus (RSV) in infants from birth through six months.[1]

Respiratory Syncytial Virus (RSV) is a common virus that usually brings on symptoms similar to the common cold, however, it can be much more serious for infants and elderly people.[2] An estimated 58,000 children under 5 years old and 60,000 to 160,000 adults 65 years and older are hospitalized each year due to an RSV infection, according to the Centers for Disease Control and Prevention (CDC).[3]

Pfizer’s submission was based on the positive top-line results from the phase 3 MATISSE (MATernal Immunization Study for Safety and Efficacy) clinical trial, which evaluated the efficacy, safety, and immunogenicity of RSVpreF against medically attended lower respiratory tract illness (MA-LRTI) and severe MA-LRTI in infants born to healthy women vaccinated during pregnancy.[4] The data will be presented in the upcoming CDC ACIP meeting on February 23, and during the ReSViNET Foundation’s 2023 Global Conference on Novel RSV Preventive and Therapeutic Interventions.[5]

The study also showed that the bivalent vaccine induced a stronger neutralizing antibody response against new Omicron sublineages in participants 55 years of age and older. For those over 55 who participated in the study, superiority of the bivalent vaccine over the original vaccine was demonstrated in terms of Omicron BA.4/BA.5-neutralizing antibodies elicited.

Pfizer is also partnered with GlaxoSmithKline (GSK) to develop a RSV vaccine for older adults called AReSVi. Along with the RSVpreF, the companies are also developing a bivalent vaccine which has been tested in a clinical trial and induced a more robust neutralizing antibody response against newer Omicron sublineages in participants 55 and older.

0. “First FDA-Approved RSV Vaccines Expected Later This Year: The Top Vaccines And Their Effectiveness” Forbes Africa, 21 Feb. 2023,

1. “Pfizer's maternal RSV vaccine filing gets priority review, setting up showdown with AstraZeneca, Sanofi” FierceBiotech, 21 Feb. 2023,

2. “RSV vaccines to receive review by FDA advisory panel” Washington Examiner, 22 Feb. 2023,

3. “FDA Action Date Set for Pfizer RSV Vaccine Candidate” Drug Topics, 24 Feb. 2023,

4. “FDA accepts BLA for Pfizer maternal RSV vaccine” Contemporary Pediatrics, 22 Feb. 2023,

5. “FDA Accepts Biologics License Application for RSV Maternal Vaccine Candidate” Pharmacy Times, 23 Feb. 2023,

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