SARS-CoV-2 y RT-PCR en pacientes asintomáticos: resultados de una cohorte de trabajadores del Aeropuerto Internacional El Dorado de Bogotá, 2020

Abstract

Introducción. La pandemia de COVID-19 ha ocasionado cerca de 25 millones de casos en el mundo. Se ha descrito que los pacientes asintomáticos pueden ser fuentes de transmisión. Sin embargo, es difícil detectarlos y no es claro su papel en la dinámica de transmisión del virus, lo que obstaculiza la implementación de estrategias para la prevención.Objetivo. Describir el comportamiento de la infección asintomática por SARS-CoV-2 en una cohorte de trabajadores del Aeropuerto Internacional El Dorado “Luis Carlos Galán Sarmiento” de Bogotá, Colombia.Materiales y métodos. Se diseñó una cohorte prospectiva de trabajadores del Aeropuerto El Dorado. El seguimiento se inició en junio de 2020 con una encuesta a cada trabajador para caracterizar sus condiciones de salud y trabajo. Cada 21 días se tomó una muestra de hisopado nasofaríngeo para detectar la presencia del SARS-CoV-2 mediante reacción en cadena de la polimerasa con transcriptasa inversa (RT-PCR). Se analizó el comportamiento del umbral del ciclo (cycle threshold) de los genes ORF1ab y N según el día de seguimiento. Resultados. En los primeros tres seguimientos de la cohorte se encontró una incidencia de la infección por SARS-CoV-2 del 16,51 %. La proporción de contactos positivos fue del 14,08 %. La mediana del umbral del ciclo fue de 33,53.Conclusión. Se determinaron las características de la infección asintomática por el SARSCoV-2 en una cohorte de trabajadores. La detección de infectados asintomáticos sigue siendo un reto para los sistemas de vigilancia epidemiológica.

The Proportion of SARS-CoV-2 Infections That Are Asymptomatic

“…Nineteen of the PCR-based studies collected data on symptoms longitudinally after testing, making it possible to distinguish between presymptomatic and asymptomatic infection ( 15 , 17 , 18 , 20 , 22 , 25 , 26 , 27 , 32 , 37–40 , 45 , 47 , 48 , 51 , 53 , 54 ). The follow-up period in these studies ranged from 2 to 70 days, with a median of 14 days (IQR, 14.0 to 15.8 days).…”

Association between cycle threshold (Ct) values and clinical and laboratory data in inpatients with COVID‐19 and asymptomatic health workers

“… 28 During a cohort of 202 Colombian workers, C t values in asymptomatic patients did not differ significantly from the symptomatic ones, the mean C t value in the asymptomatic group were 33.53 for ORF1ab gene and 33.61 for N gene, C t value in the symptomatic group was 34.13 for ORF1ab . 29 , 30 In contrast, a study regarding viral dynamics in 31 asymptomatic COVID‐19 patients showed that 22 presented symptoms after their hospital admission and that their C t values ( C t = 39) previously were significantly higher than those of symptomatic patients ( C t = 34.5). 30 In the present study, we found that patients with COVID‐19 exhibited higher C t values than AHW, similarly to C t values described by Kim et al, 27 but in our study, positive AHW were not presymptomatic subjects since they never exhibited symptoms related to COVID‐19.…”

“… 29 , 30 In contrast, a study regarding viral dynamics in 31 asymptomatic COVID‐19 patients showed that 22 presented symptoms after their hospital admission and that their C t values ( C t = 39) previously were significantly higher than those of symptomatic patients ( C t = 34.5). 30 In the present study, we found that patients with COVID‐19 exhibited higher C t values than AHW, similarly to C t values described by Kim et al, 27 but in our study, positive AHW were not presymptomatic subjects since they never exhibited symptoms related to COVID‐19.…”

8806 Russian patients demonstrate T cell count as better marker of COVID-19 clinical course severity than SARS-CoV-2 viral load

“…As we found in another study of a relatively small group of HIV/SARS-CoV-2 co-infected people, the maximum of T cell response to SARS-CoV-2 acute infection is usually observed since Day 6 to 16 34 . As well, PaO 2 /FiO 2 ratio was measured on Days 8–12 (1) to correspond roughly with T cell measurements; and (2) since it was demonstrated by different groups of researchers that severe COVID-19-associated ARDS is generally detected after the first week of the COVID-19 disease 35 – 38 . Two separate intakes and two separate measurements with calculating the average value were made in every analysis, to reduce the contribution of experimental errors.…”