Pooling samples to increase testing capacity with Xpert Xpress SARS-CoV-2 during the Covid-19 pandemic in Lao People's Democratic Republic.
Vibol IemPhonepadith XangsayarathPhonenaly ChittamanySakhone SuthepmanySouvimone SiphanthongPhimpha PaboribouneSilaphet SomphavongKonstantina KontogianniJahangir A M KhanThomas EdwardsTom WingfieldJacob CreswellJose DominguezLuis Eduardo CuevasPublished in: PloS one (2022)
The COVID-19 pandemic created the need for large-scale testing of populations. However, most laboratories do not have sufficient testing capacity for mass screening. We evaluated pooled testing of samples, as a strategy to increase testing capacity in Lao PDR. Samples of consecutive patients were tested in pools of four using the Xpert Xpress SARS CoV-2 assay. Positive pools were confirmed by individual testing, and we describe the performance of the test and savings achieved. We also diluted selected positive samples to describe its effect on the assays CT values. 1,568 patients were tested in 392 pools of four. 361 (92.1%) pools were negative and 31 (7.9%) positive. 29/31 (93.5% (95%CI 77-99%) positive pools were confirmed by individual testing of the samples but, in 2/31 (6.5%) the four individual samples were negative, suggesting contamination. Pools with only one positive sample had higher CT values (lower RNA concentrations) than the respective individual samples, indicating a dilution effect, which suggested an increased risk of false negative results with dilutions >1:10. However, this risk may be low if the prevalence of infection is high, when pools are more likely to contain more than one positive sample. Pooling saved 67% of cartridges and substantially increased testing capacity. Pooling samples increased SARS-CoV-2 testing capacity and resulted in considerable cartridge savings. Given the need for high-volume testing, countries may consider implementation of pooling for SARS-CoV-2 screening.
Keyphrases
- sars cov
- end stage renal disease
- healthcare
- ejection fraction
- primary care
- randomized controlled trial
- chronic kidney disease
- prognostic factors
- high throughput
- respiratory syndrome coronavirus
- magnetic resonance
- magnetic resonance imaging
- peritoneal dialysis
- risk factors
- study protocol
- mass spectrometry
- contrast enhanced
- patient reported outcomes
- liquid chromatography
- liquid chromatography tandem mass spectrometry
- gas chromatography
- placebo controlled