Covid-19 Omicron outbreak: How to do a RAT (rapid antigen test). Video / Gary Payinda
Shortening the isolation period for Covid-19 – but also adding a "test-to-release" policy – could cut the risk of community transmission and enable many people to return to public life earlier.
That's according to new modelling that suggests New Zealand could switch to an approach used in other countries like the US, UK and Singapore.
Under test-to-release, people confirmed with Covid-19 leave isolation only after returning a negative result on a rapid antigen test (RAT).
New Zealand's policy remained a compulsory seven-day isolation for anyone who tested positive, along with others in their household – although the Government is considering whether this should be slashed to five days.
In their report, Covid-19 Modelling Aotearoa experts compared a number of different scenarios, including the test-to-release policy used by the UK's Health Security Agency.
They found that building a test-to-release requirement into our status quo – but with a maximum isolation period of 10 days - could cut the number of cases leaving isolation while still infectious by 40 per cent, with only minor increases in the average time spent in isolation.
Alternatively, they looked at a scenario where the minimum isolation period was only five days – with a maximum of 10 days – but where people were required to return two negative tests to leave.
The also led to a 40 per cent reduction in the number of infectious cases being released – but also a 20 per cent drop in the extra hours that people spent in isolation when no longer infectious.
"Rapid antigen tests are the best tool we have to tell if people are still infectious, so it is possible to tailor an isolation period to when people are infectious," report lead author Dr Emily Harvey said.
"Some people could leave isolation sooner than seven days, some people will need to isolate for longer."
For their modelling, the researchers assumed the sensitivity of RATs at a conservative 75 per cent.
Shortening the isolation period for Covid-19 but also adding a "test-to-release" policy could cut the risk of community transmission and enable many people to leave earlier. Photo / Bevan Conley
If they instead assumed RATs to be even more sensitive, the benefits of a test-to-release regime became much greater.
"You can trust rapid antigen tests, and you should use them. When they're positive, you are likely infectious, because we now know that false positives are vanishingly unlikely."
Co-author Dr Dion O'Neale added: "The current settings also make some people isolate for longer than they need to, when they are no longer infectious."
Earlier this month, Covid-19 Response Minister Dr Ayesha Verrall told Newsroom she was open to reducing isolation periods in future – but she didn't see winter as the time to be doing that.
The next review of settings will take place next month.
National has long been calling for a shortened isolation period, along with using a test-to-work regime more widely for household contacts.
The party's Covid-19 spokesperson, Chris Bishop, said the Government "should act immediately" on the findings of the new modelling.
