Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N., Seattle, 98109, WA, USA.
Department of Biostatistics, School of Public Health, University of Washington, Seattle, 98195, WA, USA.
BMC Infect Dis. 2018 Feb 20;18(1):84. doi: 10.1186/s12879-018-2981-4.
Oral cholera vaccine (OCV) is a feasible tool to prevent or mitigate cholera outbreaks. A better understanding of the vaccine's efficacy among different age groups and how rapidly its protection wanes could help guide vaccination policy.
To estimate the level and duration of OCV efficacy, we re-analyzed data from a previously published cluster-randomized, double-blind, placebo controlled trial with five years of follow-up. We used a Cox proportional hazards model and modeled the potentially time-dependent effect of age categories on both vaccine efficacy and risk of infection in the placebo group. In addition, we investigated the impact of an outbreak period on model estimation.
Vaccine efficacy was 38% (95% CI: -2%,62%) for those vaccinated from ages 1 to under 5 years old, 85% (95% CI: 67%,93%) for those 5 to under 15 years, and 69% (95% CI: 49%,81%) for those vaccinated at ages 15 years and older. Among adult vaccinees, efficacy did not appear to wane during the trial, but there was insufficient data to assess the waning of efficacy among child vaccinees.
Through this re-analysis we were able to detect a statistically significant difference in OCV efficacy when the vaccine was administered to children under 5 years old vs. children 5 years and older. The estimated efficacies are more similar to the previously published analysis based on the first two years of follow-up than the analysis based on all five years.
ClinicalTrials.gov identifier NCT00289224.
口服霍乱疫苗（OCV）是预防或减轻霍乱暴发的可行工具。更好地了解不同年龄组疫苗的效果以及其保护作用迅速减弱的情况，有助于指导疫苗接种政策。
为了估计 OCV 功效的水平和持续时间，我们重新分析了先前发表的一项为期五年随访的、随机、双盲、安慰剂对照的聚类试验的数据。我们使用 Cox 比例风险模型，并对年龄组对疫苗功效和安慰剂组感染风险的潜在时变影响进行建模。此外，我们还研究了暴发期对模型估计的影响。
对于 1 岁以下的接种者，疫苗的有效性为 38%（95%置信区间：-2%，62%）；对于 5 岁以下的接种者，疫苗的有效性为 85%（95%置信区间：67%，93%）；对于 15 岁及以上的接种者，疫苗的有效性为 69%（95%置信区间：49%，81%）。在成年接种者中，疫苗的有效性在试验期间似乎没有减弱，但缺乏足够的数据来评估儿童接种者疫苗效力的减弱情况。
通过这项重新分析，我们能够检测到在向 5 岁以下儿童和 5 岁及以上儿童接种疫苗时 OCV 功效的统计学显著差异。估计的功效与基于前两年随访的先前发表的分析更相似，而不是基于所有五年的分析。
ClinicalTrials.gov 标识符 NCT00289224。
