Background

Long-term immunity following yellow fever vaccination remains controversial. We aimed to summarise the literature regarding the long-term protection (≥10 years) conveyed by a single dose of yellow fever vaccination.

Methods

In this systematic review and meta-analysis, we searched 11 databases from database inception to Aug 24, 2023. We included cohort and cross-sectional studies reporting immunogenicity outcomes for children or adults who received a single dose of yellow fever vaccination 10 or more years ago. Case series and single case reports were excluded. Participants who received more than one dose of yellow fever vaccination before measurement of the outcome were excluded. Identified records were reviewed by two independent reviewers. The primary outcome of the meta-analysis was the pooled seroprotection rate. Risk of bias was assessed with the Risk Of Bias In Non-randomized Studies of Interventions tool, and the Joanna Briggs Institute tool for analytical cross-sectional studies. Studies of moderate or good quality that reported seroprotection were included for random-effects meta-analysis and stratified by endemicity and specific risk groups. The study was registered with PROSPERO, CRD42023384087.

Findings

Of the 7363 articles identified by our search, 39 were eligible for inclusion for systematic review. These studies comprised 2895 individuals vaccinated 10–60 years ago. 20 studies were included in the meta-analysis. Pooled seroprotection rates were 94% (95% CI 86–99) among healthy adults in a non-endemic setting (mostly travellers) and 76% (65–85) in an endemic setting (all Brazilian studies). The pooled seroprotection rate was 47% (35–60) in children (aged 9–23 months at time of vaccination) and 61% (38–82) in people living with HIV. Reported criteria for seroprotection were highly heterogeneous.

Interpretation

The gathered evidence suggests that a single dose of yellow fever vaccination provides lifelong protection in travellers. However, in people living with HIV and children (younger than 2 years), booster doses might still be required because lower proportions of vaccinees were seroprotected 10 or more years post-vaccination. Lower observed seroprotection rates among residents of endemic areas were partly explained by the use of a higher cutoff for seroprotection that was applied in Brazil. Studies from sub-Saharan Africa were scarce and of low quality; thus no conclusions could be drawn for this region.

Funding

None.

中文翻译：

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黄热病疫苗接种后的长期免疫力：系统评价和荟萃分析

背景

黄热病疫苗接种后的长期免疫力仍存在争议。我们的目的是总结有关单剂量黄热病疫苗接种所提供的长期保护（≥10 年）的文献。

方法

在这项系统回顾和荟萃分析中，我们检索了从数据库建立到 2023 年 8 月 24 日的 11 个数据库。我们纳入了队列研究和横断面研究，报告了接受单剂黄热病疫苗接种 10 年或以上的儿童或成人的免疫原性结果前。病例系列和单个病例报告被排除在外。在测量结果之前接受超过一剂黄热病疫苗接种的参与者被排除在外。确定的记录由两名独立审查员审查。荟萃分析的主要结果是汇总血清保护率。使用非随机干预研究中的偏倚风险工具和乔安娜·布里格斯研究所的分析横断面研究工具来评估偏倚风险。报告血清保护作用的中等或良好质量的研究被纳入随机效应荟萃分析，并按流行病和特定风险组进行分层。该研究已在 PROSPERO 注册，CRD42023384087。

发现

在我们检索到的 7363 篇文章中，有 39 篇符合纳入系统评价的条件。这些研究包括 2895 名 10-60 年前接种过疫苗的个体。荟萃分析中纳入了 20 项研究。非流行环境下健康成年人（主要是旅行者）的汇总血清保护率为 94%（95% CI 86-99），流行环境下为 76%（65-85）（所有巴西研究）。儿童（接种疫苗时年龄为 9-23 个月）的汇总血清保护率为 47%（35-60），艾滋病毒感染者为 61%（38-82）。所报告的血清保护标准具有高度异质性。

解释

收集到的证据表明，单剂黄热病疫苗可为旅行者提供终生保护。然而，对于艾滋病毒感染者和儿童（2 岁以下），可能仍需要加强剂量，因为接种疫苗后 10 年或更长时间内获得血清保护的疫苗接种者比例较低。流行地区居民观察到的血清保护率较低，部分原因是巴西采用了较高的血清保护临界值。来自撒哈拉以南非洲地区的研究很少且质量低下；因此无法对该地区得出任何结论。

资金

没有任何。