COVID-19 point of care testing

Introduction

rapid point of care (POC) testing for Covid-19 is becoming more readily available in Australia, and as of Nov 1 2021, pending TGA approval home testing rapid antigen kits will become available
POC tests include:
- rt-PCR - results usually take 20min to 1 hour depending on system and require expensive equipment to run them and each device is limited to 1-4 samples at a time
- non-PCR
- rapid antigen tests - results usually take around 15 minutes and a run similar to home pregnancy test kits

generally have a swab in a self-contained tube for biohazard risk reduction
accuracy of RATs:
- if symptomatic: sensitivity 72% specificity 99.4%
- if asymptomatic (ie. “low risk Covid ED stream”): sensitivity 58% specificity 99.4%
PanBio Nasal
- cost $AU7.50 per test
- user adds agent fluid into tube
- user takes swab then inserts into tube, swirling it to mix with fluid then breaks swab off and replaces tube cap
- user then squeezes a few drops from tube onto a test device which will then display positive or negative within 15-20 minutes

Prevalence in testing cohort		Positive tests per 5000			Negative tests per 5000
%	Number infected per 5000	Total	True Pos	False Pos	Total	True Neg	False Neg
0.5%	25	39	15	25	4961	4950	10
1%	50	54	29	25	4946	4925	21
10%	500	313	291	22	4687	4478	209

Prevalence in testing cohort		Positive tests per 5000			Negative tests per 5000
%	Number infected per 5000	Total	True Pos	False Pos	Total	True Neg	False Neg
0.5%	25	43	19	25	4957	4950	6
1%	50	62	37	25	4938	4925	13
10%	500	393	371	22	4607	4477	130

negative tests probably will not change Ed Mx or streaming
- HOWEVER, a negative result may enable a lower probability Covid in the HR Covid stream to be re-allocated to LR stream
positive test in a low risk Covid could move that patient to High Risk status
positive test in a high risk Covid could move that patient to Covid zone status to be cohorted with Covid positive patients

accuracy appears to be comparable to lab-based PCR testing
mainly used in EDs, ICUs, peripheral laboratories
generally not used in main pathology labs as POCT devices are resource intensive to manage in terms of; staffing, clinical oversight, logistics, friction costs, document control/QA, validation, implementation, and are expensive to operate.

	GeneXpert Xpress (Cepheid)	Qiagen QIAstat	Roche Liat
cost of machine $AU	$65,600 for platform with capacity to perform tests 2 samples at a time $96,600 for 4 samples at a time	$50,000 for initial operational/analytical units + $37,000 for each additional add on analytical module (up to a maximum of 4)	$22,000 per Liat
cost per test $AU	$39.50	$100-$110 per test	$64 per test
time to result excl. swab handling time	45min	60min	20min
max. concurrent tests	2-4 depending upon machine	4	1
tests available	SARS-CoV-2 +/- Flu A, Flu B and RSV	SARS-CoV-2 and 21 other viral and bacterial respiratory targets	SARS-CoV-2 only