Control enrolment for serotype-specific urinary antigen detection (SSUAD) testing

To establish positivity cut-off limits for the SSUAD assay in the Mongolian population (see “urine processing” section for details), urine samples were collected from 400 adult controls in June and July 2019 (i.e. during summer months, to reduce the probability of enrolling patients with recent or current respiratory infections). Staff screened all new non-respiratory adult admissions in the medical and surgical wards on a daily basis to assess suitability as a control for the study. If patients met the control inclusion and exclusion criteria and they provided written consent to be included in the study, clinical information was collected by the doctor using a questionnaire adapted from the case questionnaire. The control questionnaire included basic demographics, medical history and medication information. Controls were required to sign an informed consent form before a urine sample was collected. Any controls that tested positive on BinaxNOW® urinary antigen test, were disenrolled as controls. None of the seven controls who tested positive reported a recent admission for pneumonia [40].

Details regarding all patients screened, their eligibility and whether they were enrolled or not, as well as reasons for exclusion were captured on a screening/enrolment log. An equal number of controls were enrolled from each of the four hospitals and based on determined targets over four age groups (18–25, 26–45, 46–65 and > 65 years).

Controls had to meet the following inclusion criteria to be eligible for study enrolment:

Able to provide written informed consent and understand all relevant study components.

Aged 18 years or older.

Willing and able to provide a urine sample.

Controls presenting with any of the following criteria were not included in the study:

Possible pneumonia or another respiratory infectious disease or signs of pneumococcal disease, with evidence of active infection.

Residing in a long-term care facility.

Known bronchial obstruction or a history of post-obstructive pneumonia. Chronic obstructive pulmonary disease was allowed, provided there had not been an exacerbation within the 3 months prior to enrolment.

Primary lung cancer or another malignancy metastatic to the lungs.

Fever (temperature of ≥38.0 °C measured by a healthcare provider).

Significant immunosuppressive disease such as AIDS, leukaemia, etc.

Received PCV and/or pneumococcal polysaccharide vaccine (PPSV) within the past 30 days.