STAMARIL® Vaccine for Yellow Fever May Be Acceptable Alternative to YF-VAX®

Surveillance data suggest that the STAMARIL vaccine is safe for protection against yellow fever, as severe adverse events were rare and outcomes were consistent with its known safety profile.

Results of a study published in the Journal of Travel Medicine support the use of the STAMARIL® vaccine for protection against yellow fever.

The YF-VAX® vaccine, a live-attenuated vaccine based on the 17D-204 strain, is the only yellow fever vaccine licensed in the United States. Due to manufacturing disruption of YF-VAX, researchers aimed to assess the safety profile of STAMARIL, an alternative 17D-204 strain-based live-attenuated yellow fever vaccine that was imported as an investigational new drug through the expanded access program (EAP) of the US Food and Drug Administration (FDA).

In this study, safety outcomes were evaluated among individuals (N=623,285) who received the STAMARIL vaccine between 2017 and 2021 across 250 clinics participating in the EAP.

Among participants included in the analysis, ages ranged from 0 to 10 (5.4%), 10 to 20 (12.9%), 20 to 30 (17.6%), 30 to 40 (18.6%), 40 to 50 (15.8%), 50 to 60 (14.2%), 60 to 70 (10.9%), and more than 70 years (4.5%). A total of 317,694 participants were women or girls, and the overall mean age among male and female participants was 38.5 and 40.3 years, respectively.

The overall rate of adverse and severe adverse events (AEs) was 208.59 and 19.5 per 100,000 individuals, respectively. A total of 7 diagnoses of yellow fever-associated neurotropic disease and 3 diagnoses of yellow fever-associated viscerotropic disease occurred among the participants, corresponding to rates of 1.1 and 0.5 per 100,000 individuals, respectively. In addition, all diagnoses occurred among participants aged 60 years and older.

[N]o new safety concerns were identified and serious adverse reactions were very rare and consistent with the known safety profile of STAMARIL.

Factors associated with AE occurrence included older age (>60 years) and female vs male sex (0.23% vs 0.19%).

Of 41 women who were vaccinated during pregnancy, no congenital anomalies were reported and 5 severe AEs occurred, including 2 adverse pregnancy outcomes that were deemed unrelated to STAMARIL vaccination.

Study limitations include potential underestimation of vaccine-related events, as there was no active surveillance program and participants were asked to self-report events.

According to the researchers, “[N]o new safety concerns were identified and serious adverse reactions were very rare and consistent with the known safety profile of STAMARIL.”

Disclosures: This research was supported by Sanofi. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Rojas A, Hachey W, Kaur G, Korejwo J, Muhammad R. Enhanced safety surveillance of STAMARIL® yellow fever vaccine provided under the Expanded Access Investigational New Drug Program in the United States. J Travel Med. Published online March 31, 2023. doi:10.1093/jtm/taad037