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The acceptability and validity of self-collected nasal swabs for detection of influenza virus infection among older adults in Thailand.

Author(s): Goyal S, Prasert K, Praphasiri P, Chittaganpitch M, Waicharoen S, Ditsungnoen D, Jaichuang S, Lindblade KA

Publication: Influenza Other Respir Viruses, 2017, Vol. 11, Page 412-417

PubMed ID: 28741903 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared the sensitivity and specificity of self-collected nasal swabs to healthcare worker-collected nasal and nasopharyngeal swab s for influenza diagnosis by real-time qRT-PCR. The adequacy of at-home self-collected nasal swabs for influenza diagnosis was also investigated. Specimens were collected at four outpatient clinics from 127 patients (≥65 y, mean age=73 y) seeking medical attention for an acute respiratory infection defined as having two or more of the following symptoms: cough or worsening of a chronic cough, measured (≥38.5°C) or subjective fever, nasal congestion, and sore throat. Clinic patients were asked to self-collect nasal specimens by inserting a foam-tipped swab approximately one inch into the anterior naris for five seconds and turning the swab twice while touching the nasal cavity walls. The swab was then placed tip-first into a test tube filled with universal transport media. Healthcare workers then collected nasal swab and nasopharyngeal swab specimens from the other nasal cavity (details not provided). Specimens were stored in a refrigerator at 2-8°C for <24 h. For at-home self-collected specimens, 26 participants (≥65 y, mean age=73 y) with the onset of an acute respiratory infection defined as the onset of cough or worsening of chronic cough were instructed to obtain nasal swab specimens following the same instructions provided to clinic participants and to store refrigerated until transport in cool boxes at 2-8°C to the centralized clinic. All self-collected (clinic and at-home) and healthcare worker-collected specimens were placed in a liquid nitrogen freezer within 24 h of collection and shipped to the Thai National Institute of Health for influenza detection by real-time qRT-PCR (details not provided). Adequacy for testing of at-home self-collected nasal swab specimens was defined as those collected within 72 h of symptom onset and testing positive for ribonuclease P (an indicator for presence of human cells) with a cycle threshold (Ct) value <37.

   Summary of Findings:

   The sensitivity of influenza diagnosis for self-collected nasal swabs was 78% using the healthcare worker-collected nasopharyngeal swabs as reference and 88% using the healthcare worker-collected nasal swabs as the reference. The specificity for influenza diagnosis was 100% for self-collected nasal swabs using either healthcare worker-collected nasopharyngeal swabs or nasal swabs as reference. Among the at-home self-collected nasal swab specimens, 92% (24/26) were considered adequate for testing.

   Biospecimens

   • Cell - Nasopharynx
   • Cell - Nasal cavity

   Preservative Types

   • Frozen

   Diagnoses:

   • Pneumonia/Respiratory Infection

   Platform:

   Analyte	Technology Platform
   RNA	Real-time qRT-PCR

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Method of cell acquisition	Self-collected nasal swab Healthcare worker-collected nasal swab Healthcare worker-collected nasopharyngeal swab
   Biospecimen Acquisition	Biospecimen location	Nasal cavity
   Real-time qRT-PCR Specific	Targeted nucleic acid	RNase P Influenza A Influenza B
   Biospecimen Acquisition	Locale of biospecimen collection	Clinic At-home

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