“That is why I trust”: A qualitative study on acceptability and feasibility of novel tongue swab diagnostics to assess people presenting with tuberculosis symptoms in Viet Nam and Zambia

Abstract Millions of tuberculosis (TB) cases are estimated to be undiagnosed and unreported annually. Sputum has been the primary approach for diagnostic testing but tongue swabs are being investigated as an alternative to expand testing. To understand potential uptake and implementation, we explored the acceptability, usability, and feasibility of tongue swab-based TB testing from the perspective of healthcare workers, people undergoing TB screening, and caregivers in Viet Nam and Zambia. We interviewed people with symptoms of TB, caregivers of children undergoing TB evaluation, and healthcare workers who collected tongue swabs (n = 76 participants) between September 2023 and February 2024. Interviews were analyzed using framework analysis to elucidate preferences, experiences, and acceptability of tongue swabs vs. sputum. Findings were further organized according to acceptability and feasibility to understand barriers and facilitators to uptake. Most participants preferred tongue swab to sputum collection. The perceived usability and feasibility of tongue swabs were high. Key themes that influenced the acceptability of tongue swabs included ease of use, diagnostic accuracy, diagnostic yield, hygiene, risk of TB transmission during sample collection, time to test result, and trust in healthcare workers and the health system. Across interviews, many participants described tongue swabs as a comfortable and easy way to test for TB, compared to the physical discomfort and difficulty expectorating sputum. Participants described tongue swab suitability for everyone, yet perceived diagnostic accuracy was crucial in shaping test preference. Tongue swab-based testing for TB is likely to be highly acceptable and feasible if incorporated into TB diagnostic guidelines. Competing Interest Statement The authors have declared no competing interest. Funding Statement This study was funded by the Bill & Melinda Gates Foundation [INV-058608]. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The University of Zambia Biomedical Research Ethics Committee (July 13, 2023, ref no: 4041-2023) and the Hanoi Lung Hospital Ethical Committee for Biological Medical Research (August 16, 2023, ref no: 935/BVPHN-HDDD) gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability Qualitative data from this study are not publicly available to protect potential identification of participants based on their detailed responses.