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.