26 Nov 2021

Covid-19: Scientist on rapid antigen tests

From Morning Report, 7:51 am on 26 November 2021

Rapid antigen tests are being rolled out to pharmacies and businesses from next month as part of a raft of Covid-19 mitigation measures.

These tests, which detect the presence of specific proteins rather than the virus's genetic material, can miss up to 44 percent of positive Covid-19 cases, according to a new study out in the New Zealand Medical Journal.

In places with relatively little Covid-19 spread, a positive result from a rapid antigen test can in fact be more likely be a false positive than an actual case of the virus.

In New Zealand, any positive result from a rapid antigen test will require confirmation with a PCR test.

Rapid PCR tests, meanwhile, are just as accurate as the standard PCR tests which currently take between 24 to 72 hours to get results back.

University of Otago microbiologist Dr James Ussher spoke to Guyon Espiner.