RSV Vaccine Candidate Intends to Increase Neutralizing Antibody Levels in Pregnant Women

A small Phase 1/2 clinical trial has been launched by Pfizer, Inc. of its respiratory syncytial virus (RSV) vaccine candidate.

There is not a licensed vaccine to prevent RSV, at this time.

RSV is a common respiratory virus that affects the lungs and airways, with significant impact on both young children and older adults.

“RSV is a very real danger that most parents of young children fear", said Chris Felton, PharmD Clinical Pharmacist MTM and Immunization Specialist, Brookshire Grocery Company.

"Currently, isolation, hand hygiene, and sanitization are the only ways to protect the vulnerable, but the successful development of this vaccine could alleviate fears and save lives”, continued Felton.

Available prophylactic treatments for RSV are limited for use in high risk, young children, and infants, including premature infants.

Globally, there are an estimated 33 million cases of RSV annually in children less than 5 years of age, with about 3 million hospitalized and up to approximately 120,000 dying each year from complications associated with the infection.

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The highest risk of severe outcome from RSV occurs in the first months of life.

For older adults, RSV is the second leading cause of moderate to severe respiratory illness, following influenza.

It is estimated that in the United States approximately 177,000 older adults are hospitalized annually because of RSV.

This maternal vaccine candidate is intended to raise RSV neutralizing antibody levels in pregnant women who then pass these protective antibodies to their unborn child and provide immunity during the early months of an infant’s life.

Pfizer’s RSV vaccine candidate builds on foundational basic science discoveries including those made at the National Institutes of Health (NIH), which detailed the crystal structure of a key viral protein that RSV uses to attack human cells. 

They showed that the antibodies that protect humans from RSV target one form of this viral protein. 

Applying insights from this important work, Pfizer engineered and tested numerous candidates and identified those that elicited a strong and stable immune response in a pre-clinical evaluation, which led to the vaccine candidate which Pfizer is evaluating in human trials.

Edward E. Walsh, M.D., Principal Investigator, Professor of Medicine at the University of Rochester, and Head of Infectious Diseases at the Rochester General Hospital in New York, said “There is an urgent global need to develop a safe and effective vaccine as a preventative option to reduce the incidence and severity of this infection in these populations.”

The trial is designed as a Phase 1/2 randomized, placebo-controlled, observer-blind, dose-ranging study with two age groups enrolled in parallel to support both the maternal and older adult indications.

The study’s primary endpoints are safety and tolerability, and its secondary endpoint is immunogenicity.