While not downplaying the serious nature of respiratory syncytial virus (RSV) in compromised individuals, knowing the risks of the RSV vaccine- can help you make an informed decision.

 Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections (LRTI) in infants worldwide, however mortality rate is very low. 97% of infant deaths occur in underserved populations where nutrition, living conditions and hygienic practices and availability are insufficient. (1)

CDC recommends the RSV vaccine ABRYSVO for Pregnant Women (2)

The following excerpt is taken directly from the RSV vaccine ABRYSVO website. (3)

• “ABRYSVO has not been evaluated for the potential to cause carcinogenicity, genotoxicity, or impairment of male fertility.
• It is not known whether ABRYSVO is excreted in human milk. Data are not available to assess the effects of ABRYSVO on the breastfed infant or on milk production/excretion.
• The results of a post marketing observational study suggest an increased risk of Guillain-Barré syndrome during the 42 days following vaccination with ABRYSVO.”

Noted: Compared to placebo, pregnant women post vaccination experienced an elevated level of hypertension, preterm rupture of membranes, and fetal death. It is unknown if this is a correlation and not cause of vaccination.

2023 FDA Press release on approval of ABRYSVO (4)

A press release from the FDA approving ABRYSVO:” In the safety studies, low birth weight and jaundice in infants occurred at a higher rate in the pregnant ABRYSVO recipients compared to pregnant placebo recipients.”

The press release goes on to state:

“Preterm births in ABRYSVO recipients (5.7%) occurred compared to those who received placebo (4.7%). The available data are insufficient to establish or exclude a causal relationship between preterm birth and ABRYSVO. Specifically, the warning informs healthcare providers that to avoid the potential risk of preterm birth with use of ABRYSVO before 32 weeks of gestation, administer ABRYSVO as indicated in pregnant individuals at 32 through 36 weeks gestational age. Pregnant individuals who were at increased risk of preterm birth were generally excluded from clinical studies of ABRYSVO.”  

FACTS

Full term births: Infants whose mothers contracted RSV during pregnancy were found to have maternal antibodies. The antibody half-life is about a month after birth; with steady decline in antibodies up to 6 months after birth. (5)

Breast milk post RSV infected mother contains maternal RSV antibodies for about 6 months, providing protection to newborn. This provides protection as the newborn’s immune system develops. Breastfeeding has shown to reduce incidence, morbidity and mortality of RSV. (6)

ABRYSVO ingredients

Along with DNA, residual host cell proteins and more, there are two stabilizers to note: A full list of ingredients can be found at their website. (7)

Two stabilizers in ABRYSVO

• Tromethamine hydrochloride IS FDA CATEGORY C- UNKNOWN IF IT WILL HARM UNBORN BABY- (8)
• Polysorbate 80- Evidence suggests maternal intake can promote metabolic syndrome in offspring, low grade inflammation and impair microbiome. (9)

Being armed with the facts will better equip you with the ability to make the right choice for you and your unborn infant.

References

iran Liang, Donghui Liu, Yan Li, Haonan Hou, Pengxi Li, Xiaoran Ma, Peize Li, Jing Zhan, Peng Wang,Maternal polysorbate 80 intake promotes offspring metabolic syndrome through vertical microbial transmission in mice,Science of The Total Environment, Volume 909,2024,168624,ISSN 00489697,https://doi.org/10.1016/j.scitotenv.2023.168624.(https://www.sciencedirect.com/science/article/pii/S0048969723072522)

Munro APS, Martinón-Torres F, Drysdale SB, Faust SN. The disease burden of respiratory syncytial virus in Infants. Curr Opin Infect Dis. 2023 Oct 1;36(5):379-384. doi: 10.1097/QCO.0000000000000952. Epub 2023 Aug 23. PMID: 37610444; PMCID: PMC10487373.

Centers for Disease Control and Prevention. (2024, May 16). Protect Your Baby From RSV. Retrieved February 4, 2025, from https://www.cdc.gov/rsv/vaccines/protect-infants.html

Pfizer Laboratories Div Pfizer Inc. (2025, January). ABRYSVO (Respiratory Syncytial Virus Vaccine) for injection, for intramuscular use: Highlights of prescribing information. Retrieved March 8, 2025, from https://labeling.pfizer.com/ShowLabeling.aspx?id=19589

FDA. (2023, August 21). FDA approves first vaccine for pregnant individuals to prevent RSV in infants. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/fda-approves-first-vaccine-pregnant-individuals-prevent-rsv-infants

Cox KR, Mandelbaum RS, Brueggmann D, Ouzounian JG, Matsuo K. Pregnant patients with respiratory syncytial virus infection: assessment of characteristics and maternal morbidity at delivery. AJOG Glob Rep. 2023 Nov 11;4(1):100289. doi: 10.1016/j.xagr.2023.100289. PMID: 38090541; PMCID: PMC10711461.

Anderson, E. J., & Doffinger, R. (2024). The role of antibody-mediated immunity in protecting children from respiratory syncytial virus. European Respiratory Review, 33(174), 240106. https://doi.org/10.1183/16000617.0106-2024

Pfizer Medical Information. (n.d.). Abrysvo (Respiratory Syncytial Virus Vaccine) description. Retrieved from https://www.pfizermedicalinformation.com/patient/abrysvo/description

Kaiser Permanente. (n.d.). Tromethamine. Retrieved from https://wa.kaiserpermanente.org/kbase/topic.jhtml?docId=d00472a1&secId=d00472a1-Header