ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Catalonia, Spain.
CIBER de Enfermedades Infecciosas, Madrid, Spain.
BMC Med. 2021 Nov 23;19(1):309. doi: 10.1186/s12916-021-02184-1.
Surveillance tools to estimate viral transmission dynamics in young populations are essential to guide recommendations for school opening and management during viral epidemics. Ideally, sensitive techniques are required to detect low viral load exposures among asymptomatic children. We aimed to estimate SARS-CoV-2 infection rates in children and adult populations in a school-like environment during the initial COVID-19 pandemic waves using an antibody-based field-deployable and non-invasive approach.
Saliva antibody conversion defined as ≥ 4-fold increase in IgM, IgA, and/or IgG levels to five SARS-CoV-2 antigens including spike and nucleocapsid constructs was evaluated in 1509 children and 396 adults by high-throughput Luminex assays in samples collected weekly in 22 summer schools and 2 pre-schools in 27 venues in Barcelona, Spain, from June 29th to July 31st, 2020.
Saliva antibody conversion between two visits over a 5-week period was 3.22% (49/1518) or 2.36% if accounting for potentially cross-reactive antibodies, six times higher than the cumulative infection rate (0.53%) assessed by weekly saliva RT-PCR screening. IgG conversion was higher in adults (2.94%, 11/374) than children (1.31%, 15/1144) (p=0.035), IgG and IgA levels moderately increased with age, and antibodies were higher in females. Most antibody converters increased both IgG and IgA antibodies but some augmented either IgG or IgA, with a faster decay over time for IgA than IgG. Nucleocapsid rather than spike was the main antigen target. Anti-spike antibodies were significantly higher in individuals not reporting symptoms than symptomatic individuals, suggesting a protective role against COVID-19.
Saliva antibody profiling including three isotypes and multiplexing antigens is a useful and user-friendlier tool for screening pediatric populations to detect low viral load exposures among children, particularly while they are not vaccinated and vulnerable to highly contagious variants, and to recommend public health policies during pandemics.
监测工具可用于评估儿童人群中的病毒传播动态，对于指导学校在病毒流行期间的开放和管理建议至关重要。理想情况下，需要使用敏感技术来检测无症状儿童中的低病毒载量暴露。我们旨在使用基于抗体的现场部署和非侵入性方法，在新冠疫情早期的波次中，在类似学校的环境中估算儿童和成人人群中的 SARS-CoV-2 感染率。
我们通过高通量 Luminex 分析，评估了 2020 年 6 月 29 日至 7 月 31 日期间，在西班牙巴塞罗那的 27 个地点的 22 所暑期学校和 2 所学前班中，每周采集的 1509 名儿童和 396 名成人的样本中，5 种 SARS-CoV-2 抗原（包括刺突蛋白和核衣壳构建体）的 IgM、IgA 和/或 IgG 水平≥ 4 倍升高的情况，定义为唾液抗体转换。
在 5 周的时间内进行两次访问，唾液抗体转换率为 3.22%（49/1518），如果考虑可能存在交叉反应的抗体，则为 2.36%，是每周唾液 RT-PCR 筛查评估的累积感染率（0.53%）的 6 倍。成年人（2.94%，11/374）的 IgG 转换率高于儿童（1.31%，15/1144）（p=0.035），IgG 和 IgA 水平随年龄增长而适度增加，女性的抗体水平更高。大多数抗体转换者 IgG 和 IgA 抗体均增加，但有些仅增加 IgG 或 IgA，且 IgA 衰减速度快于 IgG。核衣壳而非刺突蛋白是主要的抗原靶标。与有症状个体相比，无症状个体的抗刺突抗体显著更高，表明其对 COVID-19 具有保护作用。
包括三种同种型和多重抗原的唾液抗体分析是一种有用且更易于使用的工具，可用于筛查儿科人群，以检测儿童中的低病毒载量暴露，尤其是在他们未接种疫苗且易受高传染性变异株影响的情况下，以及在大流行期间建议公共卫生政策。
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