SARS-COV-2 Infection and Specific Antibody Detection on Health Care Workers from a Military Hospital in Madrid, Spain

This study aims to assess the COVID-19 seroprevalence in HCW at the Hospital Central de la Defensa Gómez Ulla (HCDGU) (Madrid). From 27 April to 10 June 2020 nasopharyngeal swab and serum samples from employees were processed in order to evaluate their seroprevalence and infective situation. Employees were classified according to their exposure to SARS-CoV-2 infection as high, moderate, and low exposure groups (level 1, level 2, and level 3, respectively). A specific real-time polymerase chain reaction (RT-PCR) was run to diagnose each patient, whereas the qualitative detection of IgG antibodies to SARS-CoV-2 was performed by means of an immunoassay. In total, 2781 HCW were screened. From this sample, 30 employees (1.1%) were infected with SARS-CoV-2 and 450 (16.2%) were positive to SARS-CoV-2-IgG antibodies. The seroprevalence was higher in the high exposure group.The seroprevalence of antibodies against SARS-CoV-2 among employees without any COVID-19 training was higher than in those who received COVID-19 training (14.5% vs 18.6%, P = 0.035). The seroprevalence in military and civilian personnel in level 1 was 18.2% and 20.0%, respectively (P = 0.4616), while in level 2 it was 6.0% and 16.0% (P = 0.0008) and in level 3 it was 16.7% and 10.2% (P = 0.0315). The results from the present study have shown that the high exposure group and HCW not receiving specific training against COVID-19 showed higher seroprevalence. Furthermore, the military employees from this hospital presented low percentage of seroprevalence.