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Early-Morning vs Spot Posterior Oropharyngeal Saliva for Diagnosis of SARS-CoV-2 Infection: Implication of Timing of Specimen Collection for Community-Wide Screening.
Hung, Derek Ling-Lung; Li, Xin; Chiu, Kelvin Hei-Yeung; Yip, Cyril Chik-Yan; To, Kelvin Kai-Wang; Chan, Jasper Fuk-Woo; Sridhar, Siddharth; Chung, Tom Wai-Hin; Lung, Kwok-Cheung; Liu, Raymond Wai-To; Kwan, Grace Sze-Wai; Hung, Ivan Fan-Ngai; Cheng, Vincent Chi-Chung; Yuen, Kwok-Yung.
  • Hung DL; Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China.
  • Li X; Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China.
  • Chiu KH; Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China.
  • Yip CC; Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China.
  • To KK; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
  • Chan JF; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
  • Sridhar S; Department of Clinical Microbiology and Infection, The University of Hong Kong-Shenzhen Hospital, Shenzhen, Guangdong Province, China.
  • Chung TW; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
  • Lung KC; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
  • Liu RW; Department of Clinical Microbiology and Infection, The University of Hong Kong-Shenzhen Hospital, Shenzhen, Guangdong Province, China.
  • Kwan GS; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
  • Hung IF; Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
  • Cheng VC; Department of Microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China.
  • Yuen KY; Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong Special Administrative Region, China.
Open Forum Infect Dis ; 7(6): ofaa210, 2020 Jun.
Article in English | MEDLINE | ID: covidwho-1387982
ABSTRACT

BACKGROUND:

Posterior oropharyngeal saliva is increasingly recognized as a valid respiratory specimen for SARS-CoV-2 diagnosis. It is easy to collect and suitable for community-wide screening. The optimal timing of collection is currently unknown, and we speculate that an early-morning specimen before oral hygiene and breakfast would increase the diagnostic yield.

METHODS:

Posterior oropharyngeal saliva was collected at 5 different time points within the same day from 18 patients with previously confirmed SARS-CoV-2 infection by molecular testing. Cycle threshold (Ct) values were compared.

RESULTS:

There was an overall trend of lower Ct values from specimens collected in the early morning, with a gradual decrease of viral load towards nighttime, but reaching statistical significance only when compared with the specimens collected at bedtime. Eight out of 13 subjects had a higher viral load in the early morning than the rest of the 4 time points (before lunch, before teatime at 3 pm, before dinner, before bedtime).

CONCLUSIONS:

The result suggests a diurnal variation of viral shedding from the upper respiratory tract with a trend showing higher viral load in the early morning. For community screening purposes, posterior oropharyngeal saliva could be taken throughout the day, but preferably in the early morning to maximize the yield.
Keywords

Full text: Available Collection: International databases Database: MEDLINE Type of study: Diagnostic study Language: English Journal: Open Forum Infect Dis Year: 2020 Document Type: Article Affiliation country: OFID

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Full text: Available Collection: International databases Database: MEDLINE Type of study: Diagnostic study Language: English Journal: Open Forum Infect Dis Year: 2020 Document Type: Article Affiliation country: OFID