Validation of RT-qPCR test for SARS-CoV-2 in saliva specimens.

BACKGROUND: Saliva samples may be an easier, faster, safer, and cost-saving alternative to NPS samples, and can be self-collected by the patient. Whether SARS-CoV-2 RT-qPCR in saliva is more accurate than in nasopharyngeal swaps (NPS) is uncertain. We evaluated the accuracy of the RT-qPCR in both types of samples, assuming both approaches were imperfect. METHODS: We assessed the limit of detection (LoD) of RT-qPCR in each type of sample. We collected paired NPS and saliva samples and tested them using the Berlin Protocol to detect SARS-CoV-2 envelope protein (E). We used a Bayesian latent class analysis (BLCA) to estimate the sensitivity and specificity of each test, while accounting for their conditional dependence. RESULTS: The LoD were 10 copies/mL in saliva and 100 copies/mL in NPS. Paired samples of saliva and NPS were collected in 412 participants. Out of 68 infected cases, 14 were positive only in saliva. RT-qPCR sensitivity ranged from 82.7 % (95 % CrI: 54.8, 94.8) in NPS to 84.5 % (50.9, 96.5) in saliva. Corresponding specificities were 99.1 % (95 % CrI: 95.3, 99.8) and 98.4 %(95 % CrI: 92.8, 99.7). CONCLUSIONS: SARS-CoV-2 RT-qPCR test in saliva specimens has a similar or better accuracy than RT-qPCR test in NPS. Saliva specimens may be ideal for surveillance in general population, particularly in children, and in healthcare or other personnel in need of serial testing.

[Incidence of respiratory symptoms and the association with air pollution in preschoolers: a multilevel analysis]. / Incidencia de síntomas respiratorios y su asociación con contaminación atmosférica en preescolares: un análisis multinivel.

The aim of this study was to evaluate the association between air pollution and respiratory symptoms in preschoolers from Bucaramanga, Colombia. A cohort study was conducted by reporting daily symptoms in preschoolers living in two zones of the city with different PM10 air pollution levels. Individual and neighborhood variables were included in a multilevel analysis. In 707 preschoolers followed for a year, sneezing and cough with mucus were the most frequent symptoms, with incidence rates of 277.2 and 203.3 events per 100 child months at risk. In the high pollution zone, an increase of 10 microg/m3 in PM10 concentration increased the reporting of daily symptoms by 1.3. Multilevel analysis showed no statistical association between PM10 and respiratory symptoms, but asthma history, heavy traffic in front of the residence, presence of domestic pets, and dirt floors were associated with respiratory symptoms.

Incidencia de sintomas respiratorios y su asociacion con contaminacion atmosferica en preescolares: un analisis multinivel / Incidence of respiratory symptoms and the association with air pollution in preschoolers: a multilevel analysis

El objetivo del estudio fue determinar la asociacion entre contaminacion atmosferica y el desarrollo de sintomas respiratorios en preescolares de Bucaramanga, Colombia. Se realizo un estudio de cohorte durante un ano, registrando sintomas en preescolares residentes en dos zonas de la ciudad con mediciones extremas de PM10 y se ajusto por variables individuales y residenciales con un modelo multinivel. Se siguieron 707 preescolares. El estornudo y la tos con flemas fueron los sintomas mas frecuentes con tasas de incidencia de 277,2 y 203,3 eventos por 100 ninos-mes en riesgo. En la zona de mayor contaminacion, un incremento de 10µg/m³ en la concentracion atmosferica de PM10 incremento en 1,3 el numero de sintomas diarios reportados. El analisis multinivel mostro ausencia de asociacion entre PM10 y sintomas respiratorios y que la historia de asma, la exposicion a alto flujo vehicular frente a la vivienda, la presencia de animales domesticos y de suelos de tierra, son las variables que tienen mayor efecto sobre la presencia de sintomas en esta poblacion de preescolares.

The aim of this study was to evaluate the association between air pollution and respiratory symptoms in preschoolers from Bucaramanga, Colombia. A cohort study was conducted by reporting daily symptoms in preschoolers living in two zones of the city with different PM10 air pollution levels. Individual and neighborhood variables were included in a multilevel analysis. In 707 preschoolers followed for a year, sneezing and cough with mucus were the most frequent symptoms, with incidence rates of 277.2 and 203.3 events per 100 child months at risk. In the high pollution zone, an increase of 10µg/m3 in PM10 concentration increased the reporting of daily symptoms by 1.3. Multilevel analysis showed no statistical association between PM10 and respiratory symptoms, but asthma history, heavy traffic in front of the residence, presence of domestic pets, and dirt floors were associated with respiratory symptoms.