Statistical Modelling of Waning Immunity After Shanchol™ Vaccination: A Prospective Cohort Study

Area of Science:

• Public Health
• Vaccinology
• Immunology

Background:

• Cholera poses a significant threat in endemic regions.
• Oral cholera vaccines (Shanchol™) are crucial for control, but supply is limited.
• Understanding vaccine antibody kinetics is vital for effective revaccination strategies.

Purpose of the Study:

• To determine the kinetics of vaccine-induced vibriocidal antibodies after Shanchol™ vaccination.
• To assess how prior vaccination history influences antibody response timing and duration.
• To provide data for optimizing cholera vaccine booster schedules in endemic areas.

Main Methods:

• Prospective cohort study in Zambia involving adults (18-65 years) receiving two Shanchol™ doses.
• Serum antibody titres (Ogawa and Inaba) measured at baseline and multiple time points post-vaccination.
• Serotype-specific mixed-effects models used to analyze antibody titre trajectories and derive peak timing and half-lives.

Main Results:

• Antibody titres peaked around day 36-37 post-vaccination for both Ogawa and Inaba serotypes.
• Post-peak half-lives were approximately 37-41 days for Ogawa and 42-46 days for Inaba.
• Antibody kinetics showed minimal variation across participants with zero, one, or two prior Shanchol™ doses.

Conclusions:

• Shanchol™ vaccination elicits vibriocidal antibody responses that peak around 5 weeks and wane over the subsequent 5-7 weeks.
• Antibody decay kinetics were similar regardless of prior vaccination history.
• Findings support evidence-based decisions on revaccination timing in cholera-endemic settings.