Getachew Tesfaye et al.

Armauer Hansen Research Institute

Abstract

Background: severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is responsible for coronavirus disease 2019 (COVID-19). The World Health Organization (WHO) has declared the COVID-19 outbreak as a global pandemic on March 11, 2020. The gold standard for the diagnosis of COVID-19 is detection of SARS-CoV2 RNA by real-time RT-PCR and the recommended sample is nasopharyngeal swab (NPS). Here, we showed that saliva could be a good alternative sample to detect SARS-CoV2 RNA in COVID-19 patients.

Materials and methods: Pair of nasopharyngeal swab and saliva samples were collected from 102 symptomatic COVID-19 patients. Samples were collected from confirmed COVID-19 patients and admitted to St. Paul hospital, one of the COVID-19 health care facilities in Addis Ababa, within five to seven days after they were tested positive for SARS-CoV2 using NPS samples by reverse transcriptase polymerase chain reaction (RT-PCR). We tested the presence of SARS‐CoV2 RNA in paired saliva and NPS by RT-PCR, and compared their positivity rate, viral load, and duration of viral RNA shedding.

Results: on the day of admission to hospital, from the total of 102 patients 93 (91.18%) were tested positive and 9 (8.82%) were negative for SARSA-CoV2 RNA in saliva whereas 54 (52.94%) patients tested positive and 48 (47%) were negative in NPS sample. At week two follow-up time, of the 38 pairs of saliva and NPS samples collected, viral RNA was detected in 31 (81.58%) of saliva, while only 10 (26.32%) patients were tested positive in NPS sample. A comparison of viral load from 53 pairs of NPS and saliva shows saliva contains significantly higher viral load than NPS (P < 0.001).

Conclusions: our study revealed that saliva has higher positivity rate in detecting of SARS-CoV2 RNA. In addition, COVID-19 patients show higher viral load and prolonged period of SARS-CoV-2 RNA shedding in saliva. Hence, we recommend the use of saliva as good alternative sample to NPS to diagnose COVID-19 patients.