COVID-19: less accurate self-collected saliva tests may bridge gaps

  • Caulley L & al.
  • Ann Intern Med
  • 28 Aug 2020

  • curated by Liz Scherer
  • Clinical Essentials
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Takeaway

  • Self-administered saliva tests for COVID-19 might help address specific staffing, personal protective equipment, and other testing challenges.
  • The tests are less accurate than naso/oropharyngeal swabs for COVID-19 detection but may have a place in the detection toolkit.
  • Standard swab testing might be unreliable as a reference standard.

Why this matters

  • The authors of a related study see saliva-based testing as a resolution to bottlenecks and a way to reduce exposure risk with clinic-based testing, in addition to reducing resource use.

Key results

  • 1939 paired swab and saliva samples from asymptomatic persons at high risk for COVID-19 or mildly symptomatic patients with COVID-19.
  • SARS-CoV-2 was detected in 70 samples (80.0% swabs, 68.6% saliva).
  • 48.6% (n=34) tested positive on both swab and saliva samples. 
  • Discordance seen in 31.4% (n=22) testing positive on swab only and 20% (14) testing positive by saliva only.
  • Swabs were obtained from nasopharynx in 35.7% of participants testing positive by saliva only vs 9.1% by swab only.

Study design

  • Prospective cohort analysis evaluating efficacy of self-administered saliva collection kits vs standard swab testing for COVID-19 detection.
  • Funding: None disclosed.

Limitations

  • No gold standard diagnostic.
  • Naso/oropharyngeal swabbing based on availability.
  • Limited sample size.