VAC-SIP-YF (Vaccination- Safety & Immunogenicity During Pregnancy- Yellow Fever)

Comparative Study of Tolerance and Immunogenicity Induced by Primary Yellow Fever Vaccination in Pregnant and Non-pregnant Women

The aim of this study is to compare the immunogenicity induced by yellow fever vaccination administered during pregnancy with that induced by vaccination outside pregnancy, and to assess the maternal and fetal tolerance of this vaccination.

Yellow fever (YF), caused by the yellow fever virus (YFV), is an endemic disease in tropical and subtropical regions of South America and Africa. The virus is transmitted to humans by mosquitoes and can cause severe acute illness, leading to death in 20 to 60% of cases. There is currently no antiviral treatment available.

The yellow fever vaccine is a live attenuated virus vaccine recommended for individuals living in or traveling to tropical regions of Africa and South America. Under the International Health Regulations (IHR), cross-border travelers aged one year and older must present an immunization certificate issued by a government-approved international vaccination center. Globally, between twenty and sixty million doses are administered each year.

In France, the vaccine used against Yellow Fever is Stamaril® (Sanofi Pasteur MSD), which utilizes the 17D-204 strain. Due to insufficient data on the tolerance and immunogenicity induced by yellow fever vaccination during pregnancy, specific precautions and guidelines are recommended in this scenario. Currently, pregnancy is a relative contraindication for yellow fever vaccination. It may be considered for pregnant women who cannot postpone travel, are traveling to a yellow fever endemic area, and where the benefit-risk ratio of vaccination is deemed favorable by the attending physician.

This research consists of 2 sections:

• Tolerance section: related to yellow fever vaccination, will involve solely collecting retrospective data. This first component will be conducted during a telephone call led by the investigating physician.
• Immunogenicity section: to evaluate the immune response induced by yellow fever vaccination. This second component will be conducted during a visit to the CMIP, where a blood sample will be taken.

All women will participate in the tolerance assessment component. If they wish and sign the written consent, they may also participate in the immunogenicity assessment component. Following the telephone call, an appointment at the CMIP will be scheduled.

Inclusion Criteria:

Common :

• Person over 18 years of age at the time of the first yellow fever vaccination
• Female gender
• Oral consent obtained after subject has been informed
• Subject covered by Social Security with the exception of Aide Médicale d'Etat

Specific to both groups :

• For women vaccinated during pregnancy (case): Primary yellow fever vaccination during pregnancy
• For women vaccinated outside pregnancy (control): Primary yellow fever vaccination outside pregnancy

Exclusion Criteria:

Criteria common to both sections (tolerance and immunogenicity):

• Subject having received a second yellow fever vaccination
• Persons unable to give informed consent for participation
• Women born in areas where yellow fever is endemic
• Female adults under legal protection (guardianship or trusteeship)

Specific criteria for participants in the immunogenicity section:

• Medical condition imcompatible with 18.5 mL blood
• Women who have not given written consent to participate in the study. immunogenicity