We found that the ANS had high accuracy for detection of respiratory viruses by PCR when compared with CTN (sensitivity 96% and specificity 99%). When rated by children, parents, and nurses, the ANS revealed high acceptability, with most indicating they would prefer ANS than CTN for future testing.
Selection of respiratory sampling methods in children require consideration of comfort, feasibility, diagnostic yield, time taken, and cost. Several avenues exist for respiratory viral testing including nasopharyngeal, nasal, oropharyngeal and saliva specimens. Nasal swab specimens are most frequently used in children and have high sensitivity when compared to more invasive nasopharyngeal swabs 10,11. Collection of saliva offers a less invasive method and is relatively easy to collect, however previous studies in children, comparing nasal and nasopharyngeal swab with saliva and throat swabs, have demonstrated inferior detection for respiratory viruses12,13. Adult studies investigating saliva for respiratory virus detection have described lower sensitivity and laboratory challenges due to handling of more viscous samples14. With the additional benefits of high accuracy and acceptability over standard testing, the ANS used in this study provides a new option for children amongst existing methods.
Large-scale testing of symptomatic and asymptomatic patients requires innovation in sampling methods and self-sampling15. Consideration needs to be given to respiratory testing methods that reduce procedural distress and impact from repeated procedures16. Frequent testing of asymptomatic children has been used to enable school attendance, or prior to elective hospital admissions in children with chronic illness throughout the SARS-CoV-2 pandemic. Some modelling has also suggested that accessibility and high frequency testing, may be a priority over test sensitivity in achieving effective population screening17. In a small pilot study among children aged 5–18 years, lower pain scores were reported for ANS compared with combined anterior nasal and throat swabs18. This finding is supported by our study, whereby participants and their parents reported the novel ANS caused less discomfort and was preferred over CTN. These benefits may support children to undertake more frequent testing if required and reduce procedural distress.
Methods which allow for self-collection reduce the need for clinician involvement, and associated workforce requirements, personal protective equipment usage and nosocomial exposure risk. Moreover, self-collected samples for respiratory viruses have the advantage of earlier collection timed with the onset of symptoms, which may allow better detection19. Previous studies have highlighted potential improved uptake, higher satisfaction and reassuring diagnostic accuracy in self and caregiver collected samples20,21. In this study, the median age of participants was 6.9 years, and yet 57% of participants inserted the ANS independently, highlighting the potential for self-collection in young children.
Although Australian and Victorian guidelines recommend combined anterior nasal and throat swabs for SARS- CoV-2 detection, many international guidelines accept nasal swabs alone for SARS-CoV-2 detection including the US Centers for Disease Control and Prevention22. A recent systematic review suggested nasal swabs are a clinically acceptable alternative specimen collection method23. Our data supports the use of anterior swabs to detect respiratory viruses.
Our novel ANS method has some limitations. First, PCR inhibition occurred in some samples. Whilst inhibition occurs infrequently in PCR testing, the frequency was higher than expected. We suspect the inhibition was likely attributable to the 3-D printing material used in this study for the “small” and “regular” ANS, as this has not been described in other studies using the production version of the adult sized swab4. Second, extra steps were needed to extract the PBS from the ANS. Routinely, CTN swabs are swirled in PBS, however, the shape and size of the flocked area of the ANS swab resulted in greater PBS absorption, which then required vortex and pulse spin to allow sufficient PBS to be available for extraction. These steps required laboratory training and additional handling compared to routine CTN processing. Difficulties with PBS extraction from the ANS may be alleviated by using higher volumes of PBS, or inclusion of a standardised universal transport media in the receptacle. Finally, this study included symptomatic children only, which might select those who have moderate to high viral loads.