Pilot study of participant-collected nasal swabs for acute respiratory infections in a low-income, urban population

Vargas, Celibell Y; Wang, Liqun; Castellanos de Belliard, Yaritza; Morban, Maria; Diaz, Hilbania; Larson, Elaine L; LaRussa, Philip; Saiman, Lisa; Stockwell, Melissa S

To assess feasibility, we determined the proportion of households agreeing to perform the self-swab, the proportion returning the swab, and the number of days elapsed between when the participants received the kit and when the swab arrived in the laboratory. All swabs obtained by research staff were analyzed by a commercially available multiplex reverse transcription polymerase chain reaction assay according to the manufacturer's instructions (BioFire Diagnostics, Inc., Salt Lake City, UT, USA). The assay has a limit of detection (LOD) of 1-200 tissue culture infective dose (TCID)50/mL for influenza, and an LOD of 4-30,000 TCID50/mL for non-influenza viral pathogens, of which only rhinovirus/enterovirus has an LOD of more than 5,000 TCID50/mL. The LOD for bacterial respiratory pathogens ranges from 30 colony forming units (CFU)/mL to 4,000 CFU/mL. 10 If the swab obtained for the primary research study was positive for a respiratory pathogen, the self-swab was also analyzed by multiplex reverse transcription polymerase chain reaction. The percent of self-swabs positive for the same pathogen as the corresponding swab obtained by research staff was calculated. Chi-square tests were used to assess if there were differences in demographic factors (age, sex, English proficiency, born in the US/elsewhere, and educational level) between those with a positive research swab who also had a positive self-swab versus a negative self-swab. Finally, the sensitivity of the self-swab using the research swab as the gold standard was assessed. All analyses were conducted using SPSS Statistics V22.0 (IBM Corporation, Armonk, NY, USA).