ABSTRACT
Sample pooling testing for SARS-COV-2 can be an effective tool in COVID-19 screening when resources are limited, yet it is important to assess the performance before implementation as pooling has its limitations. Our objective was to assess the efficacy of pooling samples for coronavirus 2019 (COVID-19) compared to an individual analysis by using commercial platforms for nucleic acid testing. A total of 2200 nasopharyngeal swabs for SARS-COV-2 were tested individually and in pools of 4, 8, and 10. The cycle threshold (Ct) values of the positive pooled samples were compared to their corresponding individual positive samples. In pool size 10 samples, an estimated increase of 3-Ct was obtained, which led to false negative results in low viral load positive samples. Pooling SARS COV-2 samples is an effective strategy of screening to increase laboratories' capacity and reduce costs without affecting diagnostic performance. A pool size of 8 is recommended.
ABSTRACT
Sample pooling testing for SARS-COV-2 can be an effective tool in COVID-19 screening when resources are limited, yet it is important to assess the performance before implementation as pooling has its limitations. Our objective was to assess the efficacy of pooling samples for coronavirus 2019 (COVID-19) compared to an individual analysis by using commercial platforms for nucleic acid testing. A total of 2200 nasopharyngeal swabs for SARS-COV-2 were tested individually and in pools of 4, 8, and 10. The cycle threshold (Ct) values of the positive pooled samples were compared to their corresponding individual positive samples. In pool size 10 samples, an estimated increase of 3-Ct was obtained, which led to false negative results in low viral load positive samples. Pooling SARS COV-2 samples is an effective strategy of screening to increase laboratories' capacity and reduce costs without affecting diagnostic performance. A pool size of 8 is recommended.
ABSTRACT
OBJECTIVE: Because of the rapidly emerging SARS-CoV-2 pandemic and its wide public health challenges, rapid diagnosis is essential to decrease the spread. Antigen-based rapid detection tests are available; however, insufficient data about their performance are available. METHODS: The lateral-flow immunochromatographic BIOCREDIT COVID-19 antigen test was evaluated using nasopharyngeal swabs in a viral transport medium from patients with confirmed infection, contacts, and exposed healthcare professionals at Fayoum University Hospital in Egypt. Test performance was determined in comparison to the SARS-CoV-2 real-time reverse-transcription polymerase chain reaction (RT-PCR) test. RESULTS: Three hundred ten specimens from 3 categories-patients with confirmed diagnoses of COVID-19, contacts, and exposed healthcare professionals-were included; 188 specimens were RT-PCR-positive, from which 81 were detected by rapid antigen test. Overall sensitivity was 43.1%. Sensitivity was significantly higher in specimens with high viral loads. CONCLUSION: Poor sensitivity of the BIOCREDIT COVID-19 test does not permit its use for diagnosis, and it can only be used in conjunction with RT-PCR for screening.