Comparative Effectiveness of Different Strategies of Oral Cholera Vaccination in Bangladesh: A Modeling Study

BackgroundKilled, oral cholera vaccines have proven safe and effective, and several large-scale mass cholera vaccination efforts have demonstrated the feasibility of widespread deployment. This study uses a mathematical model of cholera transmission in Bangladesh to examine the effectiveness of potential vaccination strategies.Methods & FindingsWe developed an age-structured mathematical model of cholera transmission and calibrated it to reproduce the dynamics of cholera in Matlab, Bangladesh. We used the model to predict the effectiveness of different cholera vaccination strategies over a period of 20 years. We explored vaccination programs that targeted one of three increasingly focused age groups (the entire vaccine-eligible population of age one year and older, children of ages 1 to 14 years, or preschoolers of ages 1 to 4 years) and that could occur either as campaigns recurring every five years or as continuous ongoing vaccination efforts. Our modeling results suggest that vaccinating 70% of the population would avert 90% of cholera cases in the first year but that campaign and continuous vaccination strategies differ in effectiveness over 20 years. Maintaining 70% coverage of the population would be sufficient to prevent sustained transmission of endemic cholera in Matlab, while vaccinating periodically every five years is less effective. Selectively vaccinating children 1–14 years old would prevent the most cholera cases per vaccine administered in both campaign and continuous strategies.ConclusionsWe conclude that continuous mass vaccination would be more effective against endemic cholera than periodic campaigns. Vaccinating children averts more cases per dose than vaccinating all age groups, although vaccinating only children is unlikely to control endemic cholera in Bangladesh. Careful consideration must be made before generalizing these results to other regions.背景：口服霍乱疫苗（oral cholera vaccines）已被证实安全有效，多项大规模霍乱疫苗群体性接种实践已证明其广泛部署的可行性。本研究基于孟加拉国霍乱传播的年龄结构数学模型，探究不同潜在疫苗接种策略的防控效果。 方法与结果：我们构建了霍乱传播的年龄结构数学模型，并针对孟加拉国马塔巴（Matlab）地区的霍乱流行动态进行校准，以复现该地区的霍乱传播规律。利用该模型预测未来20年内不同霍乱疫苗接种策略的效果。我们评估了三类聚焦程度逐步提升的目标人群接种方案：覆盖1岁及以上全部符合疫苗接种条件的人群、1~14岁儿童，以及1~4岁学龄前儿童；同时模拟了每5年开展一次的周期性接种，与持续进行的常规接种两种实施模式。建模结果显示，对70%的目标人群实施接种可在首年规避90%的霍乱病例，但周期性接种与持续接种策略在20年周期内的防控效果存在差异。维持70%的人群接种覆盖率可有效阻止马塔巴地区地方性霍乱（endemic cholera）的持续传播，而每5年一次的周期性接种效果相对更弱。在周期性与持续接种两种模式下，针对1~14岁儿童开展选择性接种的单位疫苗剂量所规避的霍乱病例数最多。 结论：我们认为，针对地方性霍乱，持续群体性疫苗接种的效果优于周期性接种活动。相较于覆盖全年龄段人群，针对儿童开展接种可实现单位疫苗剂量更高的病例规避量，但仅为儿童接种或难以控制孟加拉国的地方性霍乱流行。在将本研究结果推广至其他区域前，需进行审慎评估。