Institute of Tropical Pathology and Public Health, Federal University of Goias, Brazil.
Department of Nursing, Pontifical Catholic University of Goias, Brazil.
Vaccine. 2018 Jan 25;36(4):479-483. doi: 10.1016/j.vaccine.2017.12.011. Epub 2017 Dec 14.
Varicella vaccine was introduced into the Brazilian Immunization Program in October 2013, as a single-dose schedule administered at 15 months of age. Its effectiveness had not yet been assessed in the country.
A matched case-control study was carried out in São Paulo and Goiânia (Southeast and Midwest regions, respectively), Brazil. Suspected cases, were identified through a prospective surveillance established in the study sites. All cases had specimens from skin lesion collected for molecular laboratory testing. Cases were confirmed by either clinical or PCR of skin lesions and classified as mild, moderate, and severe disease. Two neighborhood controls were selected for each case. Cases and controls were aged 15-32 months and interviewed at home. Evidence of prior vaccination was obtained from vaccination cards. Univariate and multivariate logistic regression models were used, and odds ratio and its respective 95% confidence intervals were estimated. Vaccine effectiveness was estimated by comparing de odds of having received varicella vaccine among cases and controls.
A total of 168 cases and 301 controls were enrolled. Moderate and severe illness, was found in 33.3% and 9.9% of the cases. Effectiveness of a single dose varicella vaccine was 86% (95%CI 72-92%) against disease of any severity and 93% (95%CI 82-97%) against moderate and severe disease. Out of 168 cases, 81.8% had positive PCR results for wild-type strains, and 22.0% were breakthrough varicella cases. Breakthrough cases were milder compared to non-breakthrough cases (p < .001).
Effectiveness of single dose varicella vaccine in Brazil is comparable to that in other countries where breakthrough varicella cases have also been found to occur. The goal of the varicella vaccination program, along with disease burden and affordability should be taken into consideration when considering the adoption of a second dose of varicella vaccine into national immunization programs.
2013 年 10 月,水痘疫苗被纳入巴西免疫计划,采用 15 个月龄单剂接种程序。该疫苗在该国的有效性尚未得到评估。
在巴西的圣保罗和戈亚尼亚(东南部和中西部地区)进行了一项匹配病例对照研究。通过在研究地点建立的前瞻性监测来发现疑似病例。所有病例均采集皮损标本进行分子实验室检测。通过临床或皮损 PCR 确诊病例,并分为轻症、中症和重症疾病。为每个病例选择了 2 名邻居对照。病例和对照的年龄在 15-32 个月之间,并在家中接受访谈。通过疫苗接种卡获取疫苗接种的证据。采用单变量和多变量逻辑回归模型,估计比值比及其相应的 95%置信区间。通过比较病例和对照中接受水痘疫苗的几率来估计疫苗的有效性。
共纳入 168 例病例和 301 例对照。33.3%和 9.9%的病例为中症和重症疾病。一剂水痘疫苗对任何严重程度疾病的有效性为 86%(95%CI 72-92%),对中症和重症疾病的有效性为 93%(95%CI 82-97%)。在 168 例病例中,81.8%的 PCR 结果为野生型病毒株阳性,22.0%为突破性水痘病例。突破性病例比非突破性病例更轻(p<0.001)。
巴西一剂水痘疫苗的有效性与其他发现突破性水痘病例的国家相当。在考虑将水痘疫苗第二剂纳入国家免疫规划时,应考虑水痘疫苗接种计划的目标、疾病负担和可负担性。