Author(s):
Gonçalves, Juliana ; Sousa, Rita L. ; Jacinto, Maria J. ; Silva, Daniela A. ; Paula, Filipe ; Sousa, RD ; Zahedi, Sara ; Carvalho, Joana ; Cabral, MG ; Costa, Manuela ; Branco, Jaime ; Canhão, Helena ; Alves J, Delgado ; Maria Rodrigues, Ana ; Soares, Helena
Date: 2020
Persistent ID: http://hdl.handle.net/10362/110136
Origin: Repositório Institucional da UNL
Subject(s): IgA and IgG; pauci/asymptomatic COVID-19 prevalence; post-confinement community setting; SARS-CoV2; serosurvey; Medicine(all)
Description
Funding: This work was supported by FCT grants (PTDC/MECREU/29520/2017 to HS and CHRC UIDB/4923/2020, UIPD/4923/2020). JG, MJJ, and DAS are supported by FCT through /BD/128343/2017, PTDC/EGE-OGE/32573/2017, and PD/BD/137409/2018, respectively. The anti-SARSCoV-2 ELISA assay was developed within the context of Serology4COVID consortium, in which IBET (Instituto de Biologia Experimental e Tecnológica) produced and purified the Spike protein. This initiative was supported by Calouste Gulbenkian Foundation’s Emergency Fund for COVID-19, Sociedade Francisco Manuel dos Santos and Oeiras Municipality.
Seroprevalence studies are crucial both for estimating the prevalence of SARS-CoV-2 exposure and to provide a measure for the efficiency of the confinement measures. Portuguese universities were closed on March 16th 2020, when Portugal only registered 62 SARS-CoV-2 infection cases per million. We have validated a SARS-CoV-2 ELISA assay to a stabilized full-length spike protein using 216 pre-pandemic and 19 molecularly diagnosed SARS-CoV-2 positive individual's samples. At NOVA University of Lisbon, presential work was partially resumed on May 25th with staggered schedules. From June 15th to 30th, 3–4 weeks after the easing of confinement measures, we screened 1,636 collaborators of NOVA university of Lisbon for the presence of SARS-CoV-2 spike specific IgA and IgG antibodies. We found that spike-specific IgG in 50 of 1,636 participants (3.0%), none of which had anti-spike IgA antibodies. As participants self-reported as asymptomatic or paucisymptomatic, our study also provides a measurement of the prevalence of asymptomatic/paucisymptomatic SARS-CoV-2 infections. Our study suggests that essential workers have a 2-fold increase in viral exposure, when compared to non-essential workers that observed confinement. Additional serological surveys in different population subgroups will paint a broader picture of the effect of the confinement measures in the broader community.
