Antibody response to 17D yellow fever vaccine in Ghanaian infants

Area of Science:

• * Pediatric Infectious Diseases
• * Vaccinology
• * Immunology

Background:

• * Yellow fever remains a significant public health concern, particularly in endemic regions.
• * Current vaccination schedules often recommend yellow fever vaccine administration later in infancy.
• * Understanding early seroresponses and safety is crucial for optimizing infant immunization strategies.

Purpose of the Study:

• * To evaluate seroresponses to the 17D yellow fever vaccine in infants immunized at 6 versus 9 months of age.
• * To assess the safety and adverse effects of the 17D yellow fever vaccine in infants, with a focus on 6-month-old infants.
• * To determine the feasibility of earlier infant yellow fever vaccination.

Main Methods:

• * A randomized controlled trial involving 420 infants who had completed primary immunizations (BCG, OPV, DPT).
• * Infants were randomized to receive the 17D yellow fever vaccine at either 6 or 9 months of age.
• * Serum samples were collected pre-immunization and 3 months post-immunization for antibody titration against the vaccine virus.

Main Results:

• * Both 6-month and 9-month immunization groups demonstrated high seroconversion rates (98.6% and 98%, respectively).
• * Geometric Mean Titers (GMTs) of yellow fever antibodies were comparable between the two groups (158.5 at 6 months vs. 129.8 at 9 months).
• * Common adverse reactions included fever, cough, diarrhea, and local site reactions, with no statistically significant differences between the age groups.

Conclusions:

• * The 17D yellow fever vaccine elicits similar and robust seroresponses when administered at 6 or 9 months of age.
• * Immunization at 6 months of age showed good seroresponse with no significant adverse effects, supporting its potential use.
• * The 17D yellow fever vaccine can be recommended for infants at 6 months in outbreak situations or endemic areas with high risk.