It’s still too early to tell whether the Delta variant of the coronavirus is wily enough to evade the stringent Level 4 restrictions, but there are a few things to look out for, Marc Daalder reports
ANALYSIS: New Zealanders who welcomed the Government’s Level 4 lockdown decision last week likely had just one thing in mind: the debacle in New South Wales.
There, a single case of Delta spiralled into a firestorm, with nearly 1000 new cases reported every day and nearly 600 people now in hospital, including 100 in intensive care.
While some have since turned to questioning the wisdom of restrictions in places where cases have not yet turned up, like the entire South Island, the biggest question over the past few days has been a simple one: Will Level 4 work?
Were we fast enough and hard enough in stopping movement and cutting off avenues for the virus to spread? Will we go the way of New South Wales or will we follow in the footsteps of its neighbour to the north, Queensland, where a Delta outbreak was successfully crushed?
With those concerns in mind, economist, government advisor and disease modeller Rodney Jones took to the airwaves on Tuesday, warning that the increase in cases in recent days was a bad sign that lockdown wasn’t working.
But experts spoken to by Newsroom say it is still too early to make any sort of authoritative declaration like that. They also said the warning signs of an ineffective lockdown wouldn’t be found in the number of cases but in the source of them.
A matter of timing
Covid-19 had up to 11 days to spread in the community before it was detected. With the Delta strain, which is more transmissible and with which people become contagious more quickly after they are first infected, that was enough time to spawn at least six sub-clusters, spark a super-spreader event in a church community and infect more than 100 people.
In March last year, some 462 cases linked to overseas travel had entered the country by the time we went into lockdown. But less than half of these had actually been found at that stage – our official case count was just 189 and that included nearly 100 cases infected domestically.
This was the result of a testing system ill-equipped to handle a surge in demand, but also of the fact that Covid-19 cases take several days to show symptoms after being infected.
The cases we are finding this week have all either been infected prior to lockdown or been infected by a household contact after the start of lockdown. They are people who may have taken a week or so to become symptomatic and taken a day to get tested. Those tests may have then been stalled amid record levels of demand and taken another few days to be processed and publicly notified.
This is all in line with expectations, experts say.
Michael Plank, a University of Canterbury mathematics professor and disease modeller with Te Pūnaha Matatini, said he’d expect to see the effects of lockdown later this week.
“Right now is too early because we’re still seeing all of the cases that are being reported would have been infected before the lockdown,” he said.
“We’re not really getting any information in those cases about the effect that the lockdown is having. I think by Thursday or Friday, that will start to change.”
University of Otago, Wellington epidemiologist Michael Baker agreed.
“We should see, mid-this week, we should start to see a peak or decline in cases,” he said.
There are two things that might push that peak back which wouldn’t necessarily signify a failing lockdown. Baker said one of these is the fact that a number of high-risk events, like the church service, took place relatively shortly before lockdown. That prolongs the amount of time in which we might be finding significant numbers of cases.
The other delay to the peak was household transmission, Plank said. While the original “wild-type” coronavirus was pretty effective at spreading in a household, Delta seems to have doubled down on that, leading to almost everyone within the same home getting infected.
“What’s possible is that we’ll see an ongoing transmission within bubbles. Potentially, we could be looking at households with large household sizes, that could add up to quite a lot of cases,” he said.
The warning signs
So what would be concerning?
There are two things that officials and experts will be looking out for and they have nothing to do with case numbers.
The first is any cases in essential workers.
The theory behind Level 4 is that it cuts off all links between people, other than within bubbles and between people and essential businesses. Covid-19 might still be able to spread within bubbles but it should hit a hard wall after it infects everyone in a given household.
If essential workers start to become vectors for transmission – whether they work in a pharmacy or a supermarket or a hospital – then Level 4 could start to falter.
Essential workers effectively act as nodes linking a number of bubbles together. While businesses should be operating safely with masks and social distancing, a case in an essential workplace would raise alarm about the possibility that Delta is just transmissible enough to make it past those defences.
So far, however, there have been no cases in essential workers outside of a single MIQ staff member at the Ellerslie Novotel who worked a single shift while infectious. All of their work contacts are now isolating.
The second warning sign would be mystery cases turning up in the community with no link to known exposure sites or known cases. While they could have been part of an undetected branch of pre-lockdown transmission that has since been snuffed out, they could also be the harbinger of transmission between bubbles (through non-compliance) or through essential workplaces.
“If you get unlinked mystery cases popping up, if you’re seeing transmission between bubbles or a lot of cases in that essential worker group, obviously that gives the potential for transmission through the community as well,” Plank said.
“We’ll be expecting cases in household members and people who are potentially home quarantined at the moment. They’re the cases that we are not so worried about. It’s cases that have no connection with other cases or places of interest that would suggest that the lockdown is not containing as well as we’d hoped,” Baker said.
The Government has its eye on this issue in particular, Prime Minister Jacinda Ardern told Newsroom.
“When you look at New South Wales and their reporting, which says ‘Number of people out infected in the community’, those have been reasonable numbers. We don’t want that, because if we want to see our locations of interest start to reduce—as in, we’re not posting new ones—that will be because we’re finding people in lockdown and therefore not out and about,” she said on Monday.
“At the moment, we’re not long enough into Level 4 for that to be the case, when we’re finding people where they still have had pre – Level 4 movement, because they’re a case that was infected before we went into lockdown.”
While Level 4 worked before, the doubts are greater this time due to the added transmissibility of Delta.
“Last evening I spoke with my counterpart in Australia, the Department of Health secretary Professor Brendan Murphy. It struck me, he remarked during that conversation that ‘combatting Delta in the community is like dealing with a whole new virus’,” Director-General of Health Ashley Bloomfield said Tuesday, before reemphasising the importance of following the Level 4 rules.
“That is our experience in New Zealand too. Delta is unlike our previous experience. As we know, it is highly infectious and transmissible and, as we have seen, spreads rapidly.
“This re-enforces just how critical it is that people follow the Level 4 rules, staying at home, only leaving the house for essential reasons like getting a test or vaccination, going to the doctor, pharmacy or supermarket, exercising safely close to home or going to work, if you are an essential worker.”
Plank, whose past modelling has shown that Level 3 measures which contained the original virus during last August’s Auckland outbreak would fail to do so with the new variants, said it remains unclear whether Level 4 will be stringent enough.
“It really is difficult to say. We are heading into uncharted waters, really, because we have a very strict lockdown which I have no doubt will massively reduce transmission, but at the same time we’re dealing with the Delta variant which is incredibly infectious,” he said.
“It is a bit of a wait-and-see game.”