BACKGROUND In 2011, Argentina experienced its highest pertussis incidence and mortality rates of the last decade; 60% of deaths were among infants aged <2 months. In response, a dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine was recommended for all pregnant women at ≥20 weeks of gestation. Although recent studies suggest that maternal Tdap vaccination is effective at preventing infant disease, no data have come from low- or middle-income countries, nor from ones using whole-cell pertussis vaccines for primary immunization. METHODS We conducted a matched case-control evaluation to assess the effectiveness of maternal Tdap vaccination in preventing pertussis among infants aged <2 months in Argentina. Pertussis case patients identified from September 2012 to March 2016 at 6 hospital sites and confirmed by polymerase chain reaction testing were included. Five randomly selected controls were matched to each case patient by hospital site and mother's health district. We used multivariable conditional logistic regression to calculate odds ratios (ORs). Vaccine effectiveness (VE) was estimated as (1 - OR) × 100%. RESULTS Seventy-one case patients and 300 controls were included in the analysis. Forty-nine percent of case patients and 78% of controls had mothers who were vaccinated during pregnancy. Overall Tdap VE was estimated at 80.7% (95% confidence interval, 52.1%-92.2%). We found similar VE whether Tdap was administered during the second or third trimester. CONCLUSIONS Tdap vaccination during pregnancy is effective in preventing pertussis in infants aged <2 months in Argentina, with similar effectiveness whether administered during the second or third trimester of pregnancy.

中文翻译：

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阿根廷的孕产妇疫苗接种：妊娠期间预防破伤风、白喉和无细胞百日咳疫苗对 2 个月以下婴儿百日咳的有效性。

背景 2011 年，阿根廷经历了过去十年中最高的百日咳发病率和死亡率。60% 的死亡发生在 2 个月以下的婴儿中。作为回应，建议所有妊娠≥20 周的孕妇接种一剂破伤风类毒素、减量白喉类毒素和无细胞百日咳 (Tdap) 疫苗。尽管最近的研究表明，母体 Tdap 疫苗接种可有效预防婴儿疾病，但没有来自低收入或中等收入国家的数据，也没有来自使用全细胞百日咳疫苗进行初级免疫的国家的数据。方法 我们进行了匹配的病例对照评估，以评估在阿根廷小于 2 个月的婴儿中，母体 Tdap 疫苗接种预防百日咳的有效性。包括 2012 年 9 月至 2016 年 3 月在 6 个医院地点发现并通过聚合酶链反应检测确认的百日咳病例患者。五个随机选择的对照按医院地点和母亲的健康区与每个病例患者进行匹配。我们使用多变量条件逻辑回归来计算优势比 (OR)。疫苗有效性 (VE) 估计为 (1 - OR) × 100%。结果 71 名病例患者和 300 名对照者被纳入分析。49% 的病例患者和 78% 的对照组的母亲在怀孕期间接种了疫苗。总体 Tdap VE 估计为 80.7%（95% 置信区间，52.1%-92.2%）。无论是在孕中期还是孕晚期使用 Tdap，我们都发现了类似的 VE。