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COVID-19
You may not have noticed, but the third outbreak in New Zealand started in mid-September and has already been eliminated, reports Marc Daalder.
The third outbreak of Covid-19 in New Zealand is finished and dusted, just a couple of weeks after it started.
Rapid testing, isolation and tracking of a small raid of cases involving people who had recently left a Christchurch managed isolation facility (MIQ) shows that our system is working, experts say.
By comparison, the outbreak at the White House in Washington, DC is three times larger than our last outbreak, which was contained in just six cases.
A new case
On 19 September, when the Auckland cluster declined, the Ministry of Health reported a new community case of uncertain origin. The next day, the case was revealed to be a man who had returned to New Zealand in late August and left MIQ on September 11 after testing negative twice. He took a government chartered flight back to Auckland, along with other Auckland residents who had been staying at the Christchurch MIQ facility.
Despite his 14 days of isolation and his two tests, when the man developed Covid-19 symptoms a week after re-entering the community, he sought a test. The result was positive.
Officials quickly located the man’s own contacts during the time he had been in the community, as well as the contacts from the chartered flight. Within four days, all six cases related to the small outbreak were identified and transmission stopped.
The ministry began investigating a wide range of theories: Was the man harboring Covid-19 during an unusually long incubation period? Had he been infected by someone else on the plane? If so, how did that second person get infected?
The fact that the virus genome was a close match to the virus genome carried by someone else who had flown to New Zealand on the same flight and tested positive on day 12 only seemed to complicate matters further.
On September 21, the Ministry of Health reported that two domestic contacts of the new community case had tested positive. Two days later, three new cases related to the charter flight were revealed. By then, 65 of the 86 people on the chartered flight had been tested. By 1 p.m. the following day, the 31 contacts of the three new cases had been identified and isolated.
Container lids
Now we know the full story. The person who tested positive on the 12th of her stay in Christchurch apparently touched the lid of a container in the hallway several times before testing positive. Because staff do not enter rooms on MIQ premises, shared containers are provided for each floor. They are emptied and cleaned regularly, but obviously not regularly enough. All containers in the MIQ facility will now have no lids, Public Health Director Caroline McElnay said Friday.
On multiple occasions, another person on the same floor touched the lid of the container after the infected person. This person (who later tested positive as part of that September 23 family grouping) would have still been incubating the virus at the time of his own day 12 test and thus the PCR test, which is more effective for detect infectious people, came back negative. This individual who had touched the lid of the container second and then sat directly behind the man whose positive result was reported by the ministry on September 19 on the chartered flight back to Auckland. This is likely where the transmission occurred.
Both people who returned to the community while harboring the virus infected two members of the household, but not others. They sought evidence when necessary and made capable use of the NZ COVID Tracer app, the ministry says.
“It is nice to note that the extensive use of the NZ COVID Tracer app in one of these cases has significantly aided contact tracing efforts,” the September 23 Ministry of Health statement read.
Joep de Ligt, head of bioinformatics and genomics at the Institute for Environmental Science and Research (ESR), told Newsroom that this could be the first confirmed case of fomite (surface) transmission of Covid-19.
“Internationally, there has not yet been an official case of what they call fomite transmission. We could have the first one in Christchurch, where that particular individual is real and not the aerosol version of the virus,” he said.
However, the virus that remains in the air around the container as an aerosol cannot be completely excluded.
The system worked
This is the system that works as intended, health experts told Newsroom.
Michael Baker, professor of public health at the University of Otago and architect of the country’s phase-out strategy, said the validated approach the idea that Covid-19 can be removed without resorting to lockdowns.
“It’s a bit of an antidote to the idea, do we always have to shut down? No, clearly not.”
Baker says we must have a vision of the Covid-19 system in New Zealand. Every case that is detected in managed isolation is an averted outbreak. But he also wants more work done to reduce the number of cases entering the country, possibly requiring people to isolate themselves before boarding flights to return home or get tested.
“Increasingly, we should look at this as a complete system from the time people book their trip to New Zealand, to their trip to the country, their stay at the facility and what happens afterward,” he said.
“It would be a very good measure to try to reduce the number of positive people joining those plans. Because every time a positive person enters an MIQ facility, it is an additional risk. It might be reasonable, if they come from countries that are providing a large number of positive cases, they actually have to go to a hotel for a few days before they get on a plane and have a negative test. “
Siouxsie Wiles, a microbiologist at the University of Auckland, agreed that public health measures worked as they should to control this latest outbreak.
“We are experiencing small outbreaks that we are containing and stopping. When, where and how you notice an outbreak determines how you should act. It was very clear that Level 3 [in Auckland] It was because those cases came in, there was absolutely no idea where they had come from and that meant I had no idea how big it potentially was, “he said.
“Whereas, with this one, a case was determined, very quickly all the pieces fell into place. And then much less severe tools can be used to control it.”
She also said our system relies on everyone doing their part: getting tested when they have symptoms and scanning QR codes when visiting places outside of their home.
That’s something that Jacinda Ardern underlined in her own comments on Monday when she announced that Auckland would be moving to Level 1.
“Our public health systems are getting stronger all the time, but to stay at Tier 1 depends on all of us staying vigilant and playing our part. Whenever you’re in New Zealand, keep using the app. Scan wherever you go and Remind the people you are with to do the same, “he said.
Ardern said the models showed that if 35 percent of people with flu-like symptoms are tested, any potential outbreak is likely to be limited to 50 cases.
“If you’re a little sick, stay home, call Healthline and get tested. Preventing another outbreak is up to each and every one of us and we all have a role to play.”
