The Dominion Post - 2021-11-26


Fast Covid tests rival Usual lab tests – study

National News

Brittany Keogh

Tests that can detect Covid-19 in 20 minutes are as effective as the standard nasal swab testing done in laboratories across New Zealand, a study has confirmed. PCR (polymerase chain reaction) testing is considered the ‘‘gold standard’’ for determining whether a sample of saliva or nasopharyngeal secretions contains genetic material from the virus. Usually, the process, which involves heating and cooling the sample and mixing it with enzymes, takes hours but technology developed partway through last year can generate results faster. It is hoped the faster tests – known as rapid PCR tests – to triage patients in emergency departments with upper respiratory symptoms will help prevent the transmission of the virus in hospitals. But scientists say a global shortage of the kits needed to conduct them will likely stop them being more widely used. ‘‘These are just so critical to keeping our hospitals as free from Covid as possible,’’ said Otago University associate professor of immunology and microbiology James Ussher, who co-authored the research published in the New Zealand Medical Journal today. The study also looked at the accuracy of rapid antigen testing. It concluded this process could miss up to 44 per cent of Covid-19 cases, compared with traditional PCR tests. The wait time of up to 48 hours or more for results to PCR swabs has previously led to calls from National Party MP Chris Bishop for rapid testing to be used more widely. The publication of the paper, a collaboration by researchers from the Institute of Environmental Science and Research (ESR), Auckland City Hospital, Labtests and Southern Community Laboratories, came after the Government announced plans to spend $1 billion to bolster the contact tracing and testing system. Associate Health Minister Dr Ayesha Verrall said yesterday that while standard PCR tests would remain the main tool used to diagnose Covid-19, from next Wednesday rapid antigen tests would be rolled out across the health system, including in rest homes. Businesses would be able to buy rapid antigen test kits from approved suppliers to test their staff and the general public could get these at pharmacies from December 15. Results from rapid antigen tests would be confirmed with a follow-up PCR test. She added that the Government would increase laboratory capacity so they could process 60,000 per day by early next year and would make saliva-based PCR testing and rapid PCR testing more available soon. Ussher said that despite their shortfalls, rapid antigen tests had a place in the Covid-19 testing system. For example, they could be used to screen people crossing the Auckland border. Currently, this task was ‘‘taking up huge lab volumes and not turning up a huge number of positives’’. Darryl Carpenter, who oversees Covid-19 testing and supply for the Ministry of Health, said it was considering rapid PCR test and was monitoring research into them.


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