Department of Biomedical, Surgical and Dental Sciences, Università degli Studi di Milano, Milan, Italy.
Department of Health Sciences, Università degli Studi di Milano, Milan, Italy.
J Glob Health. 2024 Feb 9;14:05004. doi: 10.7189/jogh.14.05004.
When the coronavirus disease 2019 (COVID-19) pandemic broke out, most countries enforced school closures as a precautionary measure. Although COVID-19 is still present three years later, schools have been reopened. We aimed to test the association of molecular salivary testing (MST) and dried blood spot (DBS) analysis for community surveillance by investigating the immunological profile of a group of school staff during and following COVID-19 vaccination.
We conducted the study in a school in Milan from April 2021, when school staff were administered the first dose of vaccine against SARS-CoV-2, until the school year ended in June 2022. Each participant provided samples for MST and DBS one month (T1, W1) after receiving their first dose of vaccine. Subsequently, they collected weekly MST samples for five weeks (W2-W6), plus a DBS sample in the last week (T2). Both samples were collected one (T3), four (T4), and seven months (T5) after the administration of the second vaccine dose in May 2021. A final DBS sample was collected one year (T6) after T3.
Sixty participants provided 327 MSTs and 251 DBSs. None of the MST samples tested positive for SARS-CoV-2 RNA during the study period. A total of 201 DBS samples tested positive for the IgG semiquantitative analysis. Negative samples were found only at T1 (20.45%) and T2 (7.32%). We observed borderline results at T1 (4.55%), T2 (7.32%), and T4 (2.70%). The anti-SARS-CoV-2 average antibody ratio increased after the second dose between T2 and T3, and the trend peaked after the third dose between T4 and T6. We performed an immunoenzymatic assay of antibodies against nucleocapsid protein on samples collected at T1 from five participants who reported having been infected before the study and from four subjects with an abnormal increase in the antibody values at T4. Two samples tested positive in the first group and two in the second one.
Our findings show that MST and DBS could be effective tools in the active surveillance of school personnel and that schools could be considered safe settings in view of SARS-CoV-2 infection. Vaccines might have contributed to case and/or symptom reduction.
2019 年冠状病毒病（COVID-19）大流行爆发时，大多数国家都采取了关闭学校这一预防措施。尽管 COVID-19 已经出现了三年，但学校已经重新开放。我们旨在通过调查一组学校工作人员在 COVID-19 疫苗接种期间和之后的免疫状况，来检验分子唾液检测（MST）和干血斑（DBS）分析用于社区监测的相关性。
我们于 2021 年 4 月在米兰的一所学校进行了这项研究，当时学校工作人员接种了第一剂针对 SARS-CoV-2 的疫苗，直至 2022 年 6 月学年结束。每个参与者在接种第一剂疫苗后一个月（T1，W1）提供 MST 和 DBS 样本。随后，他们在接下来的五周（W2-W6）每周采集 MST 样本，最后一周（T2）采集 DBS 样本。两次样本均在 2021 年 5 月接种第二剂疫苗后一个月（T3）、四个月（T4）和七个月（T5）采集。最后一次 DBS 样本在 T3 一年后采集（T6）。
60 名参与者提供了 327 份 MST 和 251 份 DBS。在研究期间，没有一份 MST 样本检测到 SARS-CoV-2 RNA 呈阳性。共有 201 份 DBS 样本 IgG 半定量分析呈阳性。仅在 T1（20.45%）和 T2（7.32%）时发现阴性样本。我们在 T1（4.55%）、T2（7.32%）和 T4（2.70%）时观察到了边缘结果。第二次接种后，T2 和 T3 之间的抗 SARS-CoV-2 平均抗体比值增加，第三次接种后 T4 和 T6 之间的趋势达到峰值。我们对 T1 时的五个报告在研究前感染过的参与者和 T4 时抗体值异常升高的四个对象的样本进行了核衣壳蛋白抗体的免疫酶分析。第一组中有两个样本呈阳性，第二组中有两个样本呈阳性。
我们的研究结果表明，MST 和 DBS 可能是学校人员主动监测的有效工具，而且考虑到 SARS-CoV-2 感染，学校可能是安全的环境。疫苗可能有助于减少病例和/或症状。
