ABSTRACT
Introduction: The detection of SARS-CoV-2 genetic material from nasopharyngeal swab samples by RT-PCR is the most specific and sensitive way to test suspected cases. However, factors such as the sampling process, the type of hyssop used, and the anatomical area from which the sample is collected can distort the result and cause false negatives. Objective: To evaluate the reliability of CNUERO hyssops for sample collection for the SARS-CoV-2 diagnosis versus IMPROSWAB hyssops. Material and Methods: To study the reliability of hyssops developed in Cuba for swabbing for the COVID-19 diagnosis by comparing them to other hyssops successfully used for this task, 2 swabbing samples were obtained from each patient (136). One of these two samples was taken using the hyssops made in Cuba, while the other was taken using another hyssop imported from Germany. The positive detections obtained with the use of both hyssops were compared using the Fisher’ s exact test. The result of the detection of each hyssop was evaluated and compared using the ROC curve. Results: The use of CNEURO hyssops allowed the detection of 45 out of 59 positive cases, while IMPROSAWAB hyssops detected 52 out of 59 true positive cases. There were no significant differences between positive cases detected with the use of each hyssop. The sensitivity of sample detection using CNEURO hyssops was 76,3 % while the one using IMPROSWAB hyssops was 88,1 %. Hence, there are no significant differences in the detection of cases using these two hyssops. Conclusion: CNEURO hyssops are safe and reliable to be used to take nasopharyngeal samples from COVID-19 patients.
ABSTRACT
Introduction: The SARS-CoV-2 virus is a positive-strand RNA virus. The virus can also be detected in many different specimens as throat swabs, nasal swabs, sputum, saliva, blood, etc. Objective: The aim of this paper is to compare the reliability of different types of specimen collection, saliva and swabs samples for the detection of SARS-CoV-2. Material and Methods: A sample of 22 COVID-19 positive patients was selected. Paired samples from saliva, nasopharyngeal, oropharyngeal and nasopharyngeal + oropharyngeal swabs were collected on the 7th day after diagnosis. The hyssops and medium employed was IMPROSWAB and IMPROVIRAL NAT Medium, Germany. The sample evaluation was conducted through RT-PCR. The results were compared using Fisher's exact test and ROC curve. The gold standard proposed in this paper was the nasopharyngeal + oropharyngeal swabs specimen. Results: The gold standard method detected 10 true positive cases, of which oropharyngeal swabs, nasopharyngeal swabs and saliva only detected three positive cases. Significant differences (Fisher's exact test p = 0.003) were detected in the comparison between saliva and the gold standart proposed. The ROC curve analysis showed that saliva had an area under the curve of 0.650, with a 30 % of sensibility. However, the nasopharyngeal and nasopharyngeal + oropharyngeal samples had an area under curve of 0.950 and 1.000, respectively, with a sensibility of 90 % and 100 %, respectively. Conclusion: Saliva samples are not a reliable specimen for SARS-CoV-2 RNA detection. In turn, the most reliable specimens are nasopharyngeal and nasopharyngeal + oropharyngeal samples collected by swabbing. © 2021 Universidad de Ciencias Medicas de La Hab. All rights reserved.