In this Contemporary Pediatrics video interview, Octavio Ramilo, MD, chair, Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, highlighted challenges and breakthroughs to prevent respiratory syncytial virus (RSV) among the infant population.

RSV is the leading cause of infant hospitalization in the United States, with an estimated 58,000–80,000 children younger than 5 years hospitalized each year because of the disease, according to the Centers for Disease Control and Prevention (CDC).¹

The CDC also notes that "nearly every child will get RSV by the time they are 2 years old."¹

"For 60 years, we've been trying to develop new preventive strategies for RSV in children, and it has been very difficult because [of] the immune system of children," Ramilo said. "We cannot use the traditional vaccine strategy of 2, 4 and 6 months, because, number one, this infection affects the very early in life... even before they can get their routine vaccines. Second, the immune system of infants is immature, so they cannot respond so well to these attempts to do a traditional vaccination."

Developments in recent years have moved the needle in a big way for the prevention of RSV disease.

"A few years ago, there was a major observation in the RSV field, and it was the development of the clarification of the structure of the RSV fusion protein, or RSV F," explained Ramilo, who noted there are 2 forms of the protein.

"One is the pre-fusion form, and the other is the post-fusion and that allows [us] to understand what part of the protein induced more protein-neutralizing antibodies, which led to No. 1, the development of the maternal vaccines using this protein F in the pre-fusion conformation, and also to develop new monoclonal antibodies against different targets that induce very potent neutralizing antibodies," said Ramilo.

The FDA approvals of the monoclonal antibody nirsevimab (Beyfortus; Sanofi and AstraZeneca) and Pfizer's maternal vaccine Abrysvo have for the first time allowed for the prevention of RSV disease in this patient population, says Ramilo. In addition, clesrovimab (Merck) is being investigated as another potential monoclonal antibody tool to prevent RSV disease.^2-4

Click here to listen to Ramilo discussing the clinical development and recently-released clinical data for clesrovimab.

"The first one that was approved is nirsevimab," said Ramilo. "These antibodies are very unique compared to the previous antibodies that we used to have. They are more potent, and they have been genetically engineered so they can last longer. They have a prolonged half life, so one dose of the antibody will cover the whole the complete 5, 6 months of the RSV season. That has been really important, and we begin to experience improvements with this strategy."

Related: Tina Tan: Higher uptake in nirsevimab, maternal vaccine expected this RSV season

Contemporary Pediatrics' editor-in-chief Tina Tan, MD, FAAP, FIDSA, FPIDS, talks RSV immunization and the availability of prevention tools.

Click here to watch this 2-minute video interview.

References:

1. RSV in infants and young children. Centers for Disease Control and Prevention. Updated August 30, 2024. Accessed October 22, 2024. https://www.cdc.gov/rsv/infants-young-children/index.html

2. Fitch, J. Nirsevimab-alip FDA approved to prevent RSV in neonates, infants. Contemporary Pediatrics. July 17, 2023. Accessed October, 2022. https://www.contemporarypediatrics.com/view/nirsevimab-alip-fda-approved-to-prevent-rsv-in-neonates-infants

3. Fitch, J. FDA approves Pfizer’s maternal vaccine to prevent RSV in infants. Contemporary Pediatrics. August 21, 2023. Accessed October 22, 2024. https://www.contemporarypediatrics.com/view/fda-approves-pfizer-s-maternal-vaccine-to-prevent-rsv-in-infants

4. Fitch, J. Clesrovimab: A potential new player to protect against RSV. Contemporary Pediatrics. October 18, 2024. Accessed October 22, 2024. https://www.contemporarypediatrics.com/view/clesrovimab-a-potential-new-player-to-protect-against-rsv