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Pediatrics. 2013 Oct;132(4):624-30. doi: 10.1542/peds.2013-0878. Epub 2013 Sep 30.
In 2010, 9120 cases of pertussis were reported in California, more than any year since 1947. Although this resurgence has been widely attributed to waning immunity of the acellular vaccine, the role of vaccine refusal has not been explored in the published literature. Many factors likely contributed to the outbreak, including the cyclical nature of pertussis, improved diagnosis, and waning immunity; however, it is important to understand if clustering of unvaccinated individuals also played a role.
We analyzed nonmedical exemptions (NMEs) for children entering kindergarten from 2005 through 2010 and pertussis cases with onset in 2010 in California to determine if NMEs increased in that period, if children obtaining NMEs clustered spatially, if pertussis cases clustered spatially and temporally, and if there was statistically significant overlap between clusters of NMEs and cases.
Kulldorff's scan statistics identified 39 statistically significant clusters of high NME rates and 2 statistically significant clusters of pertussis cases in this time period. Census tracts within an exemptions cluster were 2.5 times more likely to be in a pertussis cluster (odds ratio = 2.47, 95% confidence interval: 2.22-2.75). More cases occurred within as compared with outside exemptions clusters (incident rate ratios = 1.20, 95% confidence interval: 1.10-1.30). The association remained significant after adjustment for demographic factors. NMEs clustered spatially and were associated with clusters of pertussis cases.
Our data suggest clustering of NMEs may have been 1 of several factors in the 2010 California pertussis resurgence.
2010 年，加利福尼亚州报告了 9120 例百日咳病例，这是自 1947 年以来的最高纪录。尽管这种复苏现象被广泛归因于无细胞疫苗免疫力下降，但在已发表的文献中尚未探讨疫苗接种拒绝的作用。许多因素可能导致了此次爆发，包括百日咳的周期性、诊断水平的提高和免疫力下降；然而，了解未接种人群的聚集是否也起到了作用是很重要的。
我们分析了 2005 年至 2010 年期间进入幼儿园的儿童的非医学豁免（NME）和 2010 年发病的百日咳病例，以确定在此期间 NME 是否增加，获得 NME 的儿童是否在空间上聚集，百日咳病例是否在空间和时间上聚集，以及 NME 集群和病例之间是否存在统计学上显著的重叠。
Kulldorff 的扫描统计数据确定了在此期间有 39 个高 NME 率的统计学显著集群和 2 个统计学显著的百日咳病例集群。豁免集群内的普查地段感染百日咳的可能性是集群外普查地段的 2.5 倍（优势比=2.47，95%置信区间：2.22-2.75）。在豁免集群内发生的病例比集群外多（发病率比=1.20，95%置信区间：1.10-1.30）。在调整人口统计学因素后，这种关联仍然显著。NME 呈空间聚集，与百日咳病例集群相关。
我们的数据表明，NME 的聚集可能是 2010 年加利福尼亚州百日咳疫情反弹的几个因素之一。
