“Test, test, test” was one of Prime Minister Jacinda Ardern’s most popular phrases during the early stages of the Covid-19 pandemic, but now Otago University epidemiologists are putting a new spin on it.
Modelling published in the New Zealand Medical Journal early Friday found more than 5500 Covid-19 tests are needed each day if the country is to pick up imported cases of the virus.
On Wednesday, the country’s laboratories processed 7403 tests, bringing the total number completed to date to almost 1.1 million.
While New Zealand often reaches the 5500-test benchmark, the study – led by public health professor Nick Wilson – found testing should be more targeted in countries like ours, where community transmission has been eliminated.
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People with Covid-19 symptoms in cities where border hotels and international airports are operating should be a focus, as well as those in port cities where shore leave is granted, to account for border control failings.
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“A surveillance system with a very high level of routine testing is probably required to detect an emerging or re-emerging Covid-19 outbreak within five weeks of a border control failure in a nation,” the study read.
The testing regime could be made more efficient and “we need to catch up with Australia in terms of wastewater testing” because it has the potential to detect outbreaks even quicker, Wilson said.
People who have the virus, or have recently recovered from it, shed fragments of the virus, it enters wastewater through bowls, sinks and drains, and can last for a number of weeks beyond a person’s infectious period.
“Sydney used the system to detect cases before they had detected them in the community, and various other countries are also exploring this,” Wilson said.
“[Institute of Environmental Science and Research] ESR is progressing this but for some reason, their progress isn’t as fast as Australia so that’s a bit disappointing. We should’ve really been progressing all these things much more rapidly than we have,” Wilson said.
ESR science leader Dr Brent Gilpin said while the agency regularly tests sewage for other viruses, it hasn’t done so for disease surveillance purposes.
But in June, the agency was given $1.66 million from the Ministry of Business, Innovation and Employment (MBIE) to develop a wastewater sampling system to help identify unrecognised infections in New Zealand.
“Wastewater testing for Covid-19 would always be complimenting nasopharyngeal swabs by PCR (nasal swab tests) which is the current gold standard, not [as a replacement] for it.
“The role of wastewater testing is to encourage or guide clinical testing. For a symptomatic person, it [won’t produce a result] quicker than if they were directly tested,” Gilpin said.
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The agency is also working with its Australian colleagues on a Covid-19 wastewater testing project.
Wilson, alongside other Otago University epidemiologists including Professor Michael Baker, Dr Amanda Kvalsvig and Dr Jennifer Summers, suggested people arriving from low-risk Covid-19 countries could spend part of their quarantine at home in a blog post.
Digital technologies could help ensure compliance. For example, Taiwan monitors quarantining individuals at home through personal or government-provided phones, the blog read.
As part of a “systematic review” of border controls, the group also urged officials to consider pre-travel quarantine and testing of travellers arriving from high-risk countries to “reduce the influx of infected individuals to New Zealand”.
Moving away from hotels being used as managed isolation and quarantine (MIQ) facilities was also put forward.
Video courtesy of RNZ.