Covid-19 Chasing down an outbreak Feature image

ScienceAugust 20, 2021

Siouxsie Wiles & Toby Morris: The hunt for the missing link in NZ’s delta outbreak

Covid-19 Chasing down an outbreak Feature image

The good news: we’re closing in on the missing link. The bad news: there’s a real chance of superspreading events. Siouxsie and Toby lay it all out.


As NZ confronts its first outbreak of the delta variant, we’ve made it our mission to provide timely, clear and sensationalism-free coverage. We can only do that work thanks to Spinoff Member contributions. Join us here.


While our first community delta cluster continues to grow, yesterday brought some really good news. Whole genome sequencing has shown the cases are a close match to someone who recently returned from Sydney, which has been in the grip of a delta outbreak since mid-June. 

Not only is New Zealand’s cluster now linked to the border, but that information means we can start to get a better handle on how long delta might have been present in the community. The person arrived from Sydney on a red zone flight on August 7. That’s 10 days before the Devonport man we know as case A tested positive for Covid-19. The Sydney returnee went straight into managed isolation at the Crowne Plaza hotel in Auckland. They returned a positive PCR test on August 9 and were transferred to the Jet Park quarantine facility that same day.

As of last night, how the delta virus transmitted from our Sydney returnee to case A remained a mystery. But it’s one that we hope contact tracing, genomic sequencing, and wastewater testing will solve. On the basis of when their symptoms started, Case A was likely infectious from August 12. That’s just five days after our returnee arrived and three days after they were transferred to Jet Park. Given people incubate the virus for a few days before they become infectious that suggests we’re looking at just one or two missing links in the transmission chain that led to case A. Of course, some of those missing links might be cases we already know about, like case A’s workmate and the workmates flatmates.

But another big question remains. How many other transmission chains did the Sydney returnee and the missing links trigger? 

Given how much more infectious the delta variant is, and the number and types of locations of interest, we could have had quite a few superspreading events happen in the last 10 days. That means we should definitely be prepared for case numbers to rise in the coming days.

But it also means that everyone in New Zealand should be keeping an eye on the Ministry of Health’s locations of interest list. (The Spinoff has plotted the locations of interest on an interactive map here.) Please come forward if you’ve been at one of them at the times listed, and please get tested if you have any symptoms that could be Covid-19. 

In the meantime, alert level four is the best place for us to be to break those chains of transmission. While we’ll likely see some spread within bubbles, the more of us that stay in our bubbles – and wear masks when we leave out bubbles – the less likely we are to get transmission between bubbles. And remember, vaccinations are continuing, don’t hesitate to book or head along if you’ve got an appointment. 

The crucial thing from here is going to be making sure delta doesn’t start spreading among our essential workers as that would undoubtedly prolong the outbreak.

Keep going!
Image: Tina Tiller
Image: Tina Tiller

ScienceAugust 19, 2021

Five reasons vaccines remain a critical weapon against gatecrashing delta

Image: Tina Tiller
Image: Tina Tiller

If enough of us get vaccinated we can kick this obnoxious party guest out of our home for good, writes Joel Rindelaub.

Right as we found out the most unwanted of tourists had started making itself at home here in New Zealand, we also learned just how rude it can be. A report released earlier Tuesday revealed that delta transmission had occurred at the Jet Park quarantine facility in July after doors across the hall were opened simultaneously for just 3-5 seconds. 

In less time than it takes to introduce yourself, delta can already move in, host an unwanted party, and leave your place a mess. 

Luckily, there is a great way to protect yourself from such obnoxious behaviour: get vaccinated. Despite an ever-changing situation, vaccines are still the best way to push back against the “Dirty Delta”. While there is still much to learn, here’s the latest on how well the vaccines can handle the new variant:

1. Recently published data indicate that two doses of the Pfizer-BioNTech vaccine (available to all New Zealanders starting September) is 88% effective at preventing symptomatic Covid-19, down from 94 percent against the original variant. Even though this news was a huge relief to clinicians, it should be noted that there are pre-print studies (i.e. those not yet peer-reviewed) that indicate this number may actually be much lower. While it is likely that there will be more breakthrough cases with delta, all studies to date have reported the same findings with regard to severe cases:

2. Vaccinations can save you from hospitalisation and death. In the delta-ravaged US, more than 99% of Covid-19 deaths are from those that were unvaccinated. While vaccines may take a hit from Delta in preventing infection, they are still extremely effective at preventing serious illness.

3. Vaccines may also be able to shorten the length of delta infection. Pre-print studies (again, read with caution) show that, while those infected with delta may have similar viral levels regardless of vaccination status, the amount of viral RNA in people who are vaccinated declines much quicker than those who are unvaccinated. This could mean vaccines lead to a reduced chance of long-term symptoms, reduced viral shedding, and overall reduced potential for transmission.  

4. Long Covid is real. Even if you don’t die from delta infection, you could still be left with issues like breathing trouble, fatigue, brain fog, depression, or possibly even sexual dysfunction. The UK estimates that more than 1 in 10 people who get Covid-19 develop symptoms that last for more than 12 weeks. At this point, it would not be surprising if Covid-19 infection becomes a risk factor for other issues down the line. Regardless of your age, the jab can help. 

5. Getting vaccinated can prevent the emergence of new variants. New Zealand is back in strict lockdown because uncontrolled infections allowed new coronavirus mutations to arise, creating a variant that is now harder to contain. Communities that get vaccinated can suppress the development of new mutations and reduce the chance of the next variant arriving abruptly.

Long story short, vaccines can help break delta transmission in the community, ultimately protecting both healthy and vulnerable people. Additionally, thanks to the effectiveness of vaccines in preventing severe symptoms, a widespread vaccine rollout can help reduce stress on an already fragile healthcare sector.

The delta is here. With the right focus, we will be able to beat it. But delta – or something like it – will inevitably return. If we want to ensure that the coronavirus remains a passing visitor instead of a permanent resident, we need to use the best tool we have. We need to get vaccinated.