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Immunologist does not see 'huge role' for rapid antigen testing in NZ

National may be calling for rapid antigen testing to be introduced in New Zealand, but an immunologist does not see a "huge role" for it at the moment. 

A file image of actual SARS-CoV-2 - commonly known as the 2019/20 coronavirus - under an electron microscope. Source: Wikimedia Commons/NIAID-RML

Dr James Ussher told Breakfast New Zealand's situation was unique in its zero tolerance for Covid-19 cases and this would be sacrificed if this form of testing was used.

The associate professor in Microbiology and Immunology at the University of Otago was adamant cases would be missed with rapid antigen testing.

"We have to be very mindful of our situation in New Zealand."

Ussher explained rapid antigen testing is not as sensitive as current molecular tests and said rapid antigen looks at a protein of the virus rather than its RNA genome.

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James Ussher says Covid-19 cases will be missed if this testing method is used by itself. Source: Breakfast

"It's not as sensitive full stop in detecting Covid-19."

Rapid antigen testing misses infections early and those who are asymptomatic, he said.

If rapid antigen testing did happen to be used, Ussher said it could be used in parallel with molecular testing. 

He did not recommend it being used as a standalone test.

If it did happen to be used for asymptomatic surveillance, Ussher said testing needed to be repeated daily or about twice a week to be "useful".

He reiterated the country could not afford to miss a case.

National's spokesperson for Covid-19 Response, Chris Bishop, later told Breakfast rapid antigen tests "have their place", particularly at the border.

He said these tests could have been used during the Delta outbreak if they were followed by a PCR test.

Bishop admitted accuracy would be traded off for a speedy result.