Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens

Eero Poukka, Henna Mäkelä, Lotta Hagberg, Thuan Vo, Hanna Nohynek, Niina Ikonen, Kirsi Liitsola, Otto Helve, Carita Savolainen-Kopra, Timothée Dub

Research output: Contribution to journalArticleScientificpeer-review

2 Downloads (Pure)


The gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection diagnosis is reverse transcription (RT)-PCR from a nasopharyngeal swab specimen (NPS). Its collection involves close contact between patients and health care workers, requiring a significant amount of workforce and putting them at risk of infection. We evaluated self-collection of alternative specimens and compared their sensitivity and cycle threshold (CT) values to those of NPS. We visited acute coronavirus disease 2019 (COVID-19) outpatients to collect concomitant NPS and gargle specimens and had patients self-collect gargle and either sputum or spit specimens the next morning. We included 40 patients and collected 40 concomitant NPS and gargle specimens, as well as 40 gargle, 22 spit, and 16 sputum specimens the next day (2 patients could not produce sputum). All specimens were as sensitive as NPS. Gargle specimens had a sensitivity of 0.97 (95% confidence interval [CI], 0.92 to 1.00), whether collected concomitantly with NPS or the next morning. Next-morning spit and sputum specimens showed sensitivities of 1.00 (95% CI, 1.00 to 1.00) and 0.94 (95% CI, 0.87 to 1.00]), respectively. The gargle specimens had significantly higher mean CT values of 29.89 (standard deviation [SD], 4.63; P < 0.001) and 29.25 (SD, 3.99; P < 0.001) when collected concomitantly and the next morning, respectively, compared to NPS (22.07 [SD, 4.63]). CT values obtained with spit (23.51 [SD, 4.57]; P = 0.11) and sputum (25.82 [SD, 9.21]; P = 0.28) specimens were close to those of NPS. All alternative specimen collection methods were as sensitive as NPS, but spit collection appeared more promising, with a low CT value and ease of collection. Our findings warrant further investigation. IMPORTANCE Control of the COVID-19 pandemic relies heavily on a test-trace-isolate strategy. The most commonly used specimen for diagnosis of SARS-CoV-2 infection is a nasopharyngeal swab. However, this method is quite uncomfortable for the patient, requires specific equipment (nose swabs and containers), and requires close proximity to health care workers, putting them at risk of infection. Developing alternative sampling strategies could decrease the burden for health care workers, help overcome potential shortages of equipment, and improve acceptability of testing by reducing patient discomfort.

Original languageEnglish
Pages (from-to)e00035-21
JournalMicrobiology spectrum
Issue number1
Publication statusPublished - 2021
Publication typeA1 Journal article-refereed


  • alternative testing methods
  • COVID-19
  • gargle
  • nasopharyngeal swab
  • SARS-CoV-2
  • spit
  • sputum

Publication forum classification

  • Publication forum level 1

ASJC Scopus subject areas

  • Physiology
  • Ecology
  • Immunology and Microbiology(all)
  • Genetics
  • Microbiology (medical)
  • Cell Biology
  • Infectious Diseases


Dive into the research topics of 'Detection of SARS-CoV-2 Infection in Gargle, Spit, and Sputum Specimens'. Together they form a unique fingerprint.

Cite this