Table 2 Contextual parameters and their uncertainty ranges

 Prevalence of current or recent SARS-CoV-2 infection (%) *

25

5

Assumption

 Proportion amongst those tested who are in acute phase

0.5–1.00

0.5–1.00

Assumption

 Of those in acute phase, number of infectious days remaining (days)

5–15

5–15

[16]

 Case fatality rate amongst hospitalised COVID-19 patients

0.20–0.30

N/A

[7]

 Case fatality reduction amongst COVID-19 patients on dexamethasone (1—risk ratio)

0.07–0.25

N/A

[7]

 NAT sensitivity (for current or recent SARS-CoV-2)

0.85–0.95

0.85–0.95

[17,18,19,20,21,22,23]

 NAT specificity

0.99–1

0.99–1

[17,18,19,20]

 NAT availability (proportion able to access NAT test)

0.1–1

0.1–1

Assumption

 Cost per NAT test ($)

20–70

20–70

 NAT turnaround time (days)

1–10

5–15

[10], Expert consultation

 Confirm Ag-RDT negative results with NAT

Y/N

Y/N

 Confirm Ag-RDT positive results with NAT **

Y/N

Y/N

 Isolate and initiate treatment (if indicated) whilst awaiting NAT result

Y

N

 Ag-RDT sensitivity for current infection, relative to NAT (%, assumed only amongst acute cases)*

0.80

0.80

[14, 15]

 Ag-RDT specificity, relative to NAT (%)*

0.98

0.98

[14, 15]

 Cost per Ag-RDT test ($)

5

5

[14]

 Sensitivity of clinical judgement in absence of NAT

0.45–0.99

0.45–0.99

[24,25,26,27]

 Specificity of clinical judgement in absence of NAT

0.20–0.70

0.20–0.50

[24,25,26,27]

 Proportion of hospitalised patients with a negative COVID-19 test result (true and false negatives) that are initiated onto dexamethasone

0.05–0.15

N/A

Assumption

 Duration of isolation (days)

10

10

[16]

 Duration of dexamethasone treatment (days)

10

N/A

[7]

 Cost of isolation per day ($)

50–350

N/A

[28,29,30]

 Cost of dexamethasone per day ($)

0.13–3.5

N/A

[31]