What is the best equation to protect people from Covid as winter cases surge? (Image: Tina Tiller)
What is the best equation to protect people from Covid as winter cases surge? (Image: Tina Tiller)

Covid-19July 6, 2022

How do Aotearoa’s Covid regulations compare to the most up-to-date science?

What is the best equation to protect people from Covid as winter cases surge? (Image: Tina Tiller)
What is the best equation to protect people from Covid as winter cases surge? (Image: Tina Tiller)

After nearly three months at the orange light setting, Shanti Mathias asks the experts if our current regulations still fit.

Aotearoa has been at the orange light setting, with widespread community transmission of Covid, since mid-April. In that time, more than half a million people have caught Covid. With Covid hospitalisations the highest they’ve been for months, and the BA.5 variant spreading, The Spinoff talked to microbiologist Siouxsie Wiles and epidemiologist Michael Baker about how the ever-evolving science does and doesn’t align with Aotearoa’s current Covid regulations.

Does two doses mean fully vaccinated?

While vaccine mandates have largely been phased out, except for healthcare workers, there’s widespread uncertainty about how many doses of the vaccine offer full protection. Second boosters for immunocompromised people and those over 50 have been available since June 28. Across the government websites which provide information about Covid, the first two doses of a mRNA Covid vaccine are now referred to as a “primary course” of the vaccine, rather than “fully vaccinated”, although this isn’t entirely consistent

Scientists say that the term ‘fully vaccinated’ needs to be replaced with ‘up to date’. (Image: Getty)

“Your vaccination should be ‘up-to-date with current criteria’,” suggests Baker, as an alternative description of vaccine status. A booster is essential for protection against omicron. Vaccine doses in the future may be tailored to providing maximum protection against particular variants of the virus. 

While 95% of eligible New Zealanders have had two vaccine doses, only 68% of that group have had a third booster dose. False perceptions “that the boosters are optional extras combined with the idea that omicron is mild, which is simply not true” may contribute to a lack of booster uptake, Wiles says. 

Test for reinfection after 29 days

On June 30, the guidance around Covid reinfection was updated, changing from not having any requirement to retest for Covid within 90 days of an infection to 29 days. “The latest evidence shows that getting reinfected with Covid-19 can occur within a short period of time,” says the government’s Covid website. However, household contacts of a case who have had Covid in the previous 90 days still do not need to isolate.

The 90-day regulation may have prevented health agencies from getting accurate data about reinfection – there is very little available data on reinfection in New Zealand – although it made sense when the primary testing method was PCR tests, which are more sensitive to any viral load. The Spinoff spoke to Baker and Wiles before the 90-day reinfection guidance changed.

Rapid antigen tests are an easy way to work out if you have been reinfected with Covid (Image: Ezra Whittaker)

“We don’t know much about reinfection in New Zealand because the advice has been for people to not get tested if they were within three months of having Covid,” says Wiles. “It’s clear now that people can get omicron more than once. If people’s symptoms reappear then it’s important for us to understand if someone has been reinfected or if they might be chronically infected. Because rapid antigen tests basically detect infectious virus, it’s crucial people get tested to help answer that question.”

Baker agrees. A cut-off date for reinfections is arbitrary, but 90 days was too long. “Reinfection is unusual within the month,” he says. “But there are well documented cases of people getting Covid within three weeks. We shouldn’t have any barriers to having something declared as a reinfection because it can happen.” 

Is seven days long enough for isolation? 

Current regulations say that “you can end self isolation seven days after your symptoms started or you tested positive, whichever came first. … You do not need a negative RAT to end self-isolation”. Guidelines also recommend that those with ongoing symptoms stay in isolation until 24 hours after their symptoms resolve. 

The science around infectiousness is complex, and very case-dependent. As many as one in four people can still be infectious seven days after symptom onset, says Wiles. Given this, RATs are a useful tool: “the beauty of using rapid antigen tests is that we have a quick and easy way of telling if someone is likely infectious. We should be using those and making sure people are staying isolated if they are still testing positive,” she says. If someone continues to test positive for several weeks, then they may be chronically infected. 

Wearing a mask after the seven-day isolation period has ended will help to prevent spread of Covid to others (Image: Tina Tiller)

“Seven days is a compromise,” says Baker. In other countries, such as the US, isolation ends after five days, but Covid cases are encouraged to wear a mask while in public to avoid infecting others. While a mix of consistent mask wearing and a “test to release” could prevent still-infectious people from spreading Covid after their isolation ends, Baker says that adding these layers into the Covid regulations would increase the complexity of guidelines and make it more difficult for people to adhere to. 

Why the regulations and science don’t match

“The regulations are a tradeoff between protecting people and the government getting society moving again,” says Baker. He compares Covid regulations to the road toll: while the interventions to prevent people getting killed on roads are well known – slower speeds, road barriers, and so on – the appetite to go places fast means that there is limited social licence to apply these limits to how people move on roads. 

Similarly, the ways to reduce the harms of the pandemic are well established. Increasing vaccination coverage, reducing virus transmission and caring for positive cases are what Baker calls the “three big opportunities” to minimise the impact of Covid. 

Given that Covid hospitalisations are currently the highest they have been since April, it could be time to revisit how Covid guidance limits harm. Baker suggests that employers could be supported to encourage a seven-day isolation period for workers with any respiratory infection, not just Covid. “We’re still in a pandemic stage,” he says. “Covid isn’t endemic yet.” If the current mortality rate of around 10 deaths a day continues all year, it will add 10% to New Zealand’s annual mortality. 

“We’ve got to balance protection against Covid with [limiting] the economic and social consequences [of restrictions],” Baker says. Currently, the mechanics of these trade offs aren’t explicit enough – and those who are most affected are not the people making decisions. Baker says it’s “the old, the vulnerable, and the disabled” who have had to reduce their social interaction due to the danger of Covid. “Their world has shrunk.”  

The Spinoff’s science content is made possible thanks to the support of The MacDiarmid Institute for Advanced Materials and Nanotechnology, a national institute devoted to scientific research.

Mad Chapman, Editor
Aotearoa continues to adapt to a new reality and The Spinoff is right there, sorting fact from fiction to bring you the latest updates and biggest stories. Help us continue this coverage, and so much more, by supporting The Spinoff Members.Madeleine Chapman, EditorJoin Members

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