Characteristics of studies included in the review (n = 32,253).

Ref- reference, N-number of individuals, ns- not stated; NPS- Nasopharyngeal swab; OPS- Oropharyngeal swab; c.alginate- Calcium Alginate; w-week, m-months, y-years, comm- community, opd-outpatient department, hosp-hospital, EPI -Expanded programme on immunisation clinic, DCC- day care centre, MCH- mother & child clinic, a any illness, b with respiratory tract infection, c perinatal follow up HIV clinic used control group, d routine check or immunisation, e medical conditions as well as routine checks, f minor illnesses no hospitalisations, g some swabbed once others swabbed more than once, h children and carers sick and well, I adults also swabbed age not specified, j hosp severe pneumonia, k tuberculosis patients, l year published, m patients returning for review after minor illness.