[Evaluation of the validity of Ag PANBIO-COVID19 in the diagnosis of SARS-CoV-2 infection in asymptomatic or mildly infected patients]. / Evaluación de la validez del Ag PANBIO-COVID19 de Abbott en el diagnóstico de la infección por SARS-CoV-2 en pacientes asintomáticos o con infección leve.

OBJECTIVE: To assess the validity of SARS-CoV-2 Antigen (Ag) detection for the diagnosis of SARS-CoV-2 infection in mildly infected or asymptomatic patients. METHODS: Observational study to evaluate diagnostic tests. Non-hospitalized patients with indication for diagnostic testing for SARS-CoV-2 infection were included. The diagnostic test to be evaluated was the determination of Ag and as a reference standard to determine the presence of viral RNA the RT-PCR was used. RESULTS: A total of 494 patients were included. Of these 71.5% (353/494) had symptoms and 28.5% (141/494) were asymptomatic (presurgery screening (35/494) and confirmed case-contact (106/494). The overall sensitivity of the Ag test was 61.1% and the specificity was 99.7%. The sensitivity and specificity in the asymptomatic group were 40% and 100% respectively, and in the symptomatic group 63.5% and 99.6% respectively. In turn, the sensitivity and specificity in the group of symptomatic patients varied according to the time of symptom evolution: in patients with recent symptoms, they were 71.4% and 99.6% respectively, while in patients with symptoms of more than 5 days of evolution, they were 26.7% and 100% respectively. In all groups studied, the presence of antigen is associated with a high viral load (Ct<30 cycles). CONCLUSIONS: The use of Ag detection test is not indicated for the diagnosis of SARS-CoV-2 infection in asymptomatic patients or with symptoms of more than 5 days of evolution, but it could be useful in patients with symptoms of 1-5 days of evolution.

Effectiveness of a SARS-CoV-2 infection prevention model in elective surgery patients - a prospective study: does universal screening make sense?

This observational study included patients who underwent pre-operative coronavirus disease 2019 (COVID-19) screening in order to preserve patient safety. Reverse transcriptase polymerase chain reaction (PCR) for severe acute respiratory syndrome coronavirus-2 was performed in 2292 of 8740 surgical procedures, and the incidence of a positive PCR result was 0.0022%. No healthcare-associated infections were detected. There was no difference in overall mortality or length of hospital stay compared with the same period from the previous year. A selective screening strategy to identify patients for PCR testing, based on isolation measures, presurgical clinical-epidemiological assessment and selected major surgeries susceptible to a poor COVID-19-related outcome, is effective and safe for patients and healthcare workers.