International Vaccine Institute, Seoul, Republic of Korea.
Vaccine. 2012 Aug 3;30(36):5389-95. doi: 10.1016/j.vaccine.2012.06.015. Epub 2012 Jun 18.
Typhoid fever is endemic in Karachi, with an incidence among children ranging from 170 to 450 per 100,000 child-years. Vaccination strategies are important for prevention, and the Vi capsular polysaccharide (ViCPS) vaccine has been shown to be effective in reducing the burden of typhoid fever.
A cluster randomized trial was conducted in three low socioeconomic urban squatter settlements in Karachi, Pakistan between 2002 and 2007. Subsamples were followed up for assessment of immune response and adverse events after vaccination.
The study participants were similar in a wide variety of socio-demographic and economic characteristics at baseline. A total of 27,231 individuals of the total target population of 51,965 in 120 clusters either received a ViCPS vaccine (13,238 [52% coverage]) or the control Hepatitis A vaccine (13,993 [53%]). Typhoid fever was diagnosed in 30 ViCPS vaccine recipients and 49 Hepatitis A vaccine recipients with an adjusted total protective effectiveness of 31% (95%CI: -28%, 63%). The adjusted total vaccine protective effectiveness was -38% (95%CI: -192%, 35%) for children aged 2-5 years and 57% (95%CI: 6%, 81%) for children 5-16 years old.
The ViCPS vaccine did not confer statistically significant protection to children in the study areas, and there was a decline in antibody response 2 years post-vaccination. However, the ViCPS vaccine showed significant total protection in children 5-16 years of age, which is consistent with other studies of ViCPS vaccine conducted in India, Nepal, China and South Africa. These findings suggest that ViCPS vaccination of school-aged children will protect the children of urban, typhoid endemic areas against typhoid fever.
伤寒在卡拉奇流行，儿童发病率为每 10 万儿童年 170 至 450 例。疫苗接种策略对于预防至关重要，Vi 荚膜多糖（ViCPS）疫苗已被证明可有效降低伤寒负担。
2002 年至 2007 年，在巴基斯坦卡拉奇的三个低社会经济城市棚户区进行了一项集群随机试验。在接种疫苗后，对亚组进行了免疫反应和不良事件评估。
研究参与者在基线时在广泛的社会人口统计学和经济特征方面相似。在总共 120 个簇中的总目标人群 51965 人中，共有 27231 人接受了 ViCPS 疫苗（52%的覆盖率为 13238 人）或对照甲型肝炎疫苗（53%的覆盖率为 13993 人）。在 30 名 ViCPS 疫苗接种者和 49 名甲型肝炎疫苗接种者中诊断出伤寒，调整后的总保护效力为 31%（95%CI：-28%，63%）。2-5 岁儿童的调整后总疫苗保护效力为-38%（95%CI：-192%，35%），5-16 岁儿童为 57%（95%CI：6%，81%）。
ViCPS 疫苗在研究区域内并未为儿童提供统计学上显著的保护作用，并且接种疫苗后 2 年抗体反应下降。然而，ViCPS 疫苗在 5-16 岁儿童中表现出显著的总保护作用，这与在印度、尼泊尔、中国和南非进行的其他 ViCPS 疫苗研究结果一致。这些发现表明，对学龄儿童进行 ViCPS 疫苗接种将保护城市伤寒流行地区的儿童免受伤寒的侵害。
