Persistence of Anti-SARS-CoV-2 Antibodies Six Months after Infection in an Outbreak with Five Hundred COVID-19 Cases in Borriana (Spain): A Prospective Cohort Study

Salvador Domènech-Montoliu,David Jovani-Sales,Manuel Sánchez-Urbano,Alba Del Rio-González,Maria Dolores Llopico-Vilanova,Sonia Valls-López,Maria Carmen León-Domingo,Claudia Dols-Bernad,Belén Cervera-Ferrer,Ursula Clerig-Arnau,Mercedes Moros-Blasco,Gema Ferrer-Abad,Raquel Ruíz-Puig,Paula Vidal-Utrillas,Cristina Notari-Rodríguez,Sara Ferrando-Rubert,Alberto Arnedo-Pena,Laura Aparisi-Esteve,Marta Latorre-Poveda,Gema Badenes-Marques,Joan Puig-Barberà,Lorna Gómez-Lanas ,María Rosario Pac-Sa ,María Fontal-Carcel

doi:10.3390/covid1010006

Abstract

In March 2020, several mass gathering events were related to the Falles festival in Borriana (Spain), resulting in a 536 laboratory-confirmed COVID-19 cases outbreak among participants. This article estimates anti-SARS-CoV-2 antibodies persistence six months after and factors associated with antibody response. A prospective population-based cohort study was carried out by the Public Health Centre of Castellon and the Emergency and Clinical Analysis and Microbiology Services of Hospital de la Plana in Vila-real. In October 2020, a seroepidemiologic study was used to estimate the persistence of anti-SARS-CoV-2 antibodies against nucleocapsid protein (N) by an electrochemiluminescence immunoassay (ECLIA) was implemented. We enrolled 484 (90.2%) of the 536 members of the initial outbreak cohort and detected persistent antibodies in 479 (99%) without reinfection episodes. Five participants had a negative antibody test. Factors associated with a negative result were a lower body mass index (BMI), and less contact with other COVID-19 cases. Among the 469 participants with two ECLIA tests, 96 (20.5%) had an increase of antibodies and 373 (79.5%) a decline. Increased antibodies were associated with older age, higher BMI, more severe illness, and low current smokers. Our results show that after a COVID-19 infection, a high proportion of cases maintain detectable anti-SARS-CoV-2 antibodies.

Highlights

At the time of writing, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)has caused 160,457,476 confirmed cases and 3,331,604 deaths globally [1]
We invited all the subjects who tested positive for SARS-CoV-2 in the outbreak of the mass gathering events (MGEs) of Falles festival to participate in a second seroepidemiological study in October 2020
We explore factors associated with the immune response, comparing the geometric mean of total anti-SARS-CoV-2 antibodies of participants in the first and second serologic surveys and the change in magnitude between tests as an increase or a decline

Summary

Introduction

At the time of writing, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)has caused 160,457,476 confirmed cases and 3,331,604 deaths globally [1]. COVID 2021, 1 main unknowns is the duration of immunity elicited after coronavirus disease (COVID-19). Serologic surveys are needed to gather evidence on the persistence and protection of the humoral immunity to SARS-CoV-2 infection [2,3], as well as the study of the cellular immunity mediated by T cells [4,5]. In the first days of March 2020, several mass gathering events (MGEs) for the Falles festival took place in Borriana, a city of 35,000 inhabitants in Castellon (Spain), and a COVID-19 outbreak ensued. During March–June 2020, an epidemiologic study whit a serologic survey of this outbreak found 570 COVID-19 cases (536 laboratory-confirmed and 34 with clinical and epidemiologic criteria), 13 admissions and one death, among 1338 participants in the MGEs; the attack rate (AR) was 42.6%

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