METHODS: Participants returned to one of six health facilities in Kinshasa in 2021, where study staff collected a brief medical history and blood specimen. We assessed neutralising antibody titres against yellow fever virus using a plaque reduction neutralisation test with a 50% cutoff (PRNT50). Participants with a PRNT50 titre of 10 or higher were considered seropositive. The primary outcome was the proportion of participants seropositive at 5 years.
RESULTS: Among the 764 participants enrolled, 566 (74%) completed the 5-year visit. 5 years after vaccination, 539 (95·2%, 95% CI 93·2-96·7) participants were seropositive, including 361 (94·3%, 91·5-96·2) of 383 who were seronegative and 178 (97·3%, 93·8-98·8) of 183 who were seropositive at baseline. Geometric mean titres (GMTs) differed significantly across age groups for those who were initially seronegative with the lowest GMT among those aged 2-5 years and highest among those aged 13 years and older.
CONCLUSIONS: A fractional dose of the 17DD yellow fever vaccine induced an immunologic response with detectable titres at 5 years among the majority of participants in the Democratic Republic of the Congo. These findings support the use of fractional-dose vaccination for outbreak prevention with the potential for sustained immunity.
BACKGROUND: Gavi, the Vaccine Alliance through the CDC Foundation.
UNASSIGNED: For the French translation of the abstract see Supplementary Materials section.
方法:参与者于2021年返回金沙萨的六个医疗机构之一,研究人员在那里收集了简短的病史和血液样本。我们使用具有50%截止值(PRNT50)的空斑减少中和试验评估了针对黄热病病毒的中和抗体滴度。PRNT50滴度为10或更高的参与者被认为是血清阳性。主要结果是5年时参与者血清阳性的比例。
结果:在764名参与者中,566(74%)完成了为期5年的访问。接种疫苗后5年,539(95·2%,95%CI93·2-96·7)参与者血清呈阳性,包括361(94·3%,91·5-96·2)383名血清阴性者和178名(97·3%,93·8-98·8)的183名基线血清阳性。对于最初为血清阴性的患者,2-5岁的GMT最低,13岁及以上的GMT最高的患者,几何平均滴度(GMT)在不同年龄段之间存在显着差异。
结论:在刚果民主共和国的大多数参与者中,部分剂量的17DD黄热病疫苗在5年时诱导了可检测滴度的免疫应答。这些发现支持使用分剂量疫苗预防爆发,并具有持续免疫的潜力。
背景:Gavi,通过CDC基金会的疫苗联盟。
■有关摘要的法语翻译,请参见补充材料部分。