Aga Khan University, Karachi, Pakistan.
Vaccine. 2013 Apr 8;31(15):1987-93. doi: 10.1016/j.vaccine.2013.02.003. Epub 2013 Feb 18.
Seroprevalence studies provide important data on performance of immunization programs, susceptible groups and populations at-risk of future outbreaks. Identifying risk factors that affect seroconversion of the oral polio vaccine (OPV) will enable the polio eradication initiatives to increase seroprevalence. This paper describes the first population-based seroprevalence survey in Pakistan.
This study evaluated the seroprevalence of poliovirus (PV) types 1, 2, and 3 antibodies to OPV in an illustrative sample of 554 subjects 6-11 months of age in three geographic locations of Pakistan (Lahore, Karachi, and Peshawar) representing a low socioeconomic at-risk populations. Antibody titers were measured and sero protection rates and geometric median titers were compared among different geographic regions and populations, as were demographics and OPV vaccination history collected by questionnaire. Univariate and multivariate analyses were conducted on subject characteristics to assess for potential risk factors for failure to sero-convert.
The average seroprevalence of PV1, PV2, and PV3 was 96.0%, 87.9% and 86.7%, respectively. The lowest sero protection rate for all three serotypes was for Karachi with 90.2%, 73.8%, and 78.8% for PV1, PV2, and PV3, respectively. Significant regional variation in PV3 seroprevalence was found (range: 74.2-100%). In the univariate analysis, age, total and campaign OPV doses were associated with higher seroprevalence, whereas stunting, respondent education and diarrhea in the past six months were significant risk factors for failure to sero-convert.
These findings demonstrate consistently high levels of antibody response to PV1 and more geographically varied response to PV2 and PV3. Additionally, important risk factors affecting seropositivity were identified.
血清流行率研究为免疫规划的实施情况、易感人群以及未来疫情爆发风险人群提供了重要数据。确定影响口服脊髓灰质炎疫苗（OPV）血清转化率的危险因素，将使消灭脊髓灰质炎倡议能够提高血清阳性率。本文描述了巴基斯坦首例基于人群的血清流行率调查。
本研究评估了巴基斯坦三个地理位置（拉合尔、卡拉奇和白沙瓦）的 554 名 6-11 个月龄儿童对 OPV 的脊灰病毒（PV）1、2 和 3 型抗体的血清流行率。通过问卷调查收集人口统计学和 OPV 接种史等数据，并测量抗体滴度，比较不同地理位置和人群的血清保护率和几何平均滴度，还对单变量和多变量分析进行了分析，以评估未能血清转换的潜在危险因素。
PV1、PV2 和 PV3 的平均血清流行率分别为 96.0%、87.9%和 86.7%。三种血清型的血清保护率最低的是卡拉奇，分别为 90.2%、73.8%和 78.8%。还发现了三种血清型的 PV3 血清流行率存在显著的地域差异（范围：74.2-100%）。在单变量分析中，年龄、总剂量和疫苗接种剂量与更高的血清流行率相关，而发育迟缓、应答者教育程度和过去六个月的腹泻是未能血清转换的重要危险因素。
这些发现表明，对 PV1 的抗体反应始终很高，而对 PV2 和 PV3 的反应则更加具有地域差异。此外，还确定了影响血清阳性率的重要危险因素。
