Aldevron Breakthrough Blog
Continuing the RSV Fight
October 23, 2024 by Patrick Paez
Children’s vaccine is the next challenge
Respiratory syncytial virus (RSV) is one of the most notable pathogens causing hospitalizations during the fall and winter seasons across most of the US. Primarily affecting the neonate, pediatric, and geriatric populations, RSV has the added complication in that certain regions of the US do not follow the seasonal pattern, leading to varying recommendations for protection in states like Florida, Alaska, Hawaii, and some US territories. Fortunately, approvals for new RSV vaccines and therapies have occurred in the past year. Unfortunately, those vaccines aren’t suitable for the pediatric population.
The history of developing an RSV vaccine aimed at the pediatric population has a long history of failure. But from that failure came many lessons on developing the target Fusion protein (F protein) antigen, resulting in three RSV vaccine approvals, all for adults ages 60 and older, with one of those approved for administration to pregnant individuals during gestational weeks 32-36 to provide infant protection upon delivery. However, the search for a direct vaccine for infants or children against RSV still continues.
It is estimated that 2.1 million children end up in clinics annually due to RSV, with about 472,000 of these patients requiring emergency care. Treatment options for children experiencing lower respiratory tract disease (LRTD) caused by RSV infection were once limited to general supportive care and a prophylactic monoclonal antibody (MAb) called SYNAGIS®. Approved in 1998, SYNAGIS targets the F protein, helping prevent infection from this pathogen.
A longer-acting prophylactic MAb called Bayfortus® was approved in July 2023, improving the duration of protection from approximately one month to five months while decreasing hospitalizations by 82% as shown in a study published in The Lancet. This chart shows the approved vaccines and prophylactic treatments for RSV as of this writing:
| Treatment Type | Name | Indications & Usage | Approval Date |
| Vaccine | Abrysvo® (Pfizer) | Weeks 32-36 pregnancy | 8/21/2023 |
| Vaccine | Abrysvo® (Pfizer) | Adults 60+ | 5/31/2023 |
| Vaccine | AREXVY (GSK) | Adults 60+ | 5/03/2023 |
| Vaccine | mRESVIA® (Moderna) | Adults 60+ | 5/31/2024 |
| MAb therapy | Bayfortus® (Sanofi) | Children 0-24 months | 7/17/2023 |
| MAb therapy | SYNAGIS® (Sobi) | Children 0-24 months | 6/01/1998 |
The tools pediatricians can use to protect their vulnerable patient population has undergone a significant expansion in the past year with the recent approvals. While there is still no vaccine for the pediatric population, the potential of using Abrysvo® for pregnant individuals during the 32-36 week gestational range appears to provide good protection for the infant against RSV after birth. Additionally, Bayfortus® may become an option for passive immunity, conferring significant long-term protection for those unable to receive the vaccine during gestation.
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Patrick Paez serves as a technical marketing manager for Aldevron’s marketing team. He earned a bachelor's degree in Pre-Medicine and Psychology, and a Ph.D. in Immunology at Virginia Commonwealth University (VCU) in Richmond, VA. His Ph.D. training at VCU's Medical College of Virginia campus was in a translational science lab at the Massey Cancer Center, where he focused on developing immunotherapeutic interventions in the field of immuno-oncology for phase 1 clinical trials.