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

In March 2020, several mass gathering events were related to the Falles festival in Borriana (Spain), resulting 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 Public Health Centre of Castellon Emergency Clinical Analysis Microbiology Services Hospital de la Plana Vila-real. October seroepidemiologic used estimate against nucleocapsid protein (N) an electrochemiluminescence immunoassay (ECLIA) implemented. We enrolled 484 (90.2%) members initial detected persistent 479 (99%) without reinfection episodes. Five participants had negative test. Factors result lower body index (BMI), less contact other cases. Among 469 two ECLIA tests, 96 (20.5%) increase 373 (79.5%) decline. Increased older age, higher BMI, more severe illness, low current smokers. Our results show that infection, high proportion maintain detectable antibodies.