Self-sampling versus physician-sampling of oropharyngeal swabs for molecular detection of respiratory viruses: a pilot study

Aim: This pilot study evaluated the adequacy of self-collected oropharyngeal swabs compared to those collected by trained physicians for molecular detection of respiratory viruses. Method: Oropharyngeal swabs1 were collected from influenza like-illness cases in Lombardy during the 2018/2019 season. Two groups of samples were considered: group 1) 131 swabs collected by general practitioners operating within the Italian Influenza Surveillance Network; group 2) 131 swabs self-collected by hospital healthcare workers (doctors, nurses, technicians, in-training students) after being trained on the sampling procedure by both an explanatory brochure describing the steps of swab collection, point-by-point, and a telephone call to a study staff member who guided sample collection. RNA was extracted from each swab and tested for the detection of the human ribonuclease P gene (RNP) by real-time RT-PCR. Samples with a cycle threshold (Ct)<35 were considered adequate for further virological analysis. Respiratory syncytial virus (RSV) was detected by real-time RT-PCR. Results: All samples were positive to RNP detection with Ct<35. The mean Ct value was 25.46 (SD: ±2.40; range: 18.65-30.10) for swabs collected by physicians and 25.93 (SD: ±2.22; range: 19.48-33.13) for self-collected swabs, with no statistically significant difference (p=0.10). RSV-positivity rates were similar among both groups (10.9% vs 7.3%; p=0.39). Conclusions: Self-collected oropharyngeal swabs resulted adequate and comparable to those collected by trained physicians for molecular detection of respiratory viruses. Self-sampling can be a worthwhile strategy of sample collection to implement molecular surveillance of respiratory viruses or to evaluate vaccine effectiveness involving population at lower costs.