Testing for Omicron may need re-evaluation--South African study

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Tue, 2021-12-28 18:51 — mike kraft

Are We Testing for Omicron Wrong? South African study suggests nasal swabs aren't the best way John Gever medpagetoday

If confirmed in follow-up research and if the diagnostics industry can pivot quickly enough, findings from a South African study could make COVID-19 testing a lot easier for patients and healthcare workers, as the SARS-CoV-2 Omicron variant becomes the dominant source of infection.

In a manuscript posted to the medRxiv preprint server on Friday, researchers from the University of Cape Town reported that saliva samples yielded more accurate results in PCR analyses when Omicron was involved compared with those collected via nasal swabs.

When patients carried the Delta variant, on the other hand, nasal swabs were more accurate, according to the group, led by Diana Hardie, MBChB, MMedPath, who also heads the diagnostic virology laboratory at Groote Schuur Hospital.

The findings came from an analysis of 382 patients tested at Groote Schuur from August through this month, with viral whole-genome sequencing performed on isolates from those with positive results. Just over 300 were tested prior to Omicron's emergence, with 31 testing positive for the Delta variant. Another 74 arrived at the hospital after Omicron became common, of whom 36 were positive for that variant.

All patients had both saliva and mid-turbinate nasal samples taken for RT-PCR analysis. The "gold standard" for positivity in the study was detection of SARS-CoV-2 RNA with either swab. ...

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