We examined the usefulness of dried spot blood and saliva samples in SARS-CoV-2 antibody analyses. We analyzed 1231 self-collected dried spot blood and saliva samples from healthcare workers. Participants filled in a questionnaire on their COVID-19 exposures, infections, and vaccinations. Anti-SARS-CoV-2 IgG, IgA, and IgM levels were determined from both samples using the GSP/DELFIA method. The level of exposure was the strongest determinant of all blood antibody classes and saliva IgG, increasing as follows: (1) no exposure (healthy, non-vaccinated), (2) exposed, (3) former COVID-19 infection, (4) one vaccination, (5) two vaccinations, and (6) vaccination and former infection. While the blood IgG assay had a 99.5% sensitivity and 75.3% specificity to distinguish participants with two vaccinations from all other types of exposure, the corresponding percentages for saliva IgG were 85.3% and 65.7%. Both blood and saliva IgG-seropositivity proportions followed similar trends to the exposures reported in the questionnaires. Self-collected dry blood and saliva spot samples combined with the GSP/DELFIA technique comprise a valuable tool to investigate an individual’s immune response to SARS-CoV-2 exposure or vaccination. Saliva IgG has high potential to monitor vaccination response wane, since the sample is non-invasive and easy to collect.

我们检查了干点血和唾液样本在 SARS-CoV-2 抗体分析中的用途。我们分析了来自医护人员的 1231 份自行采集的干点血和唾液样本。参与者填写了一份关于他们的 COVID-19 暴露、感染和疫苗接种的问卷。使用 GSP/DELFIA 方法从两个样本中测定抗 SARS-CoV-2 IgG、IgA 和 IgM 水平。暴露水平是所有血液抗体类别和唾液 IgG 中最强的决定因素，增加如下：(1) 未暴露（健康，未接种疫苗），(2) 暴露，(3) 既往 COVID-19 感染，(4 ) 一次疫苗接种，(5) 两次疫苗接种，以及 (6) 疫苗接种和既往感染。虽然血液 IgG 检测具有 99.5% 的敏感性和 75.3% 的特异性，可以将接种过两次疫苗的参与者与所有其他类型的暴露人群区分开来，唾液 IgG 的相应百分比为 85.3% 和 65.7%。血液和唾液 IgG 血清学阳性比例的趋势与问卷中报告的暴露相似。自收集的干血和唾液斑点样本与 GSP/DELFIA 技术相结合，构成了研究个体对 SARS-CoV-2 暴露或疫苗接种的免疫反应的宝贵工具。唾液 IgG 具有监测疫苗接种反应减弱的巨大潜力，因为样本是非侵入性的且易于收集。自收集的干血和唾液斑点样本与 GSP/DELFIA 技术相结合，构成了研究个体对 SARS-CoV-2 暴露或疫苗接种的免疫反应的宝贵工具。唾液 IgG 具有监测疫苗接种反应减弱的巨大潜力，因为样本是非侵入性的且易于收集。自收集的干血和唾液斑点样本与 GSP/DELFIA 技术相结合，构成了研究个体对 SARS-CoV-2 暴露或疫苗接种的免疫反应的宝贵工具。唾液 IgG 具有监测疫苗接种反应减弱的巨大潜力，因为样本是非侵入性的且易于收集。