Rolling dice as infection strikes again
Analysis Derek Cheng looks into the new Auckland case and random virus transmission
Every time there is a new coronavirus outbreak, there’s a roll of the dice. That’s because Covid-19 is so random in who it infects and how easily.
The latest episode of our ongoing battle with the virus stars an extremely unfortunate Defence Force serviceman, who passed it to an Auckland student he doesn’t know and has never met.
Investigations are ongoing, but after extensive interviews with both of them, they don’t appear to have interacted.
Even if the virus jumped from him to her in a chance encounter, it would defy conventional wisdom that Covid-19 is normally transmitted between people who spend 15 minutes within 2m of each other.
This appears to be the kind of rare, impossible-to-anticipate transmission that no lines of defence could prevent, short of having everyone in personal protective gear and staying 2m apart from each other at all times.
All we know for sure at this point is that they were in the same area at the same time.
On Thursday last week, the serviceman had lunch at the Mezze Bar which, according to Google maps, is 82m from A-Z Collections, the shop where the student worked.
Right next to the shop are two public toilet cubicles. Did they use the same cubicle shortly after each other?
Transmission via air particles is possible, as is surface transmission, though it is rare.
There was the lift button in the Rydges Hotel (though that might have also been air particles), and the shared rubbish bin lid in the Crowne Plaza in Christchurch.
The latest case caused enough concern for Prime Minister Jacinda Ardern to immediately fly to Wellington after being told of the infection.
The last time a case with no link to the border or a known case popped up, Auckland went into level 3 lockdown and there were 179 cases across two regions.
Lockdown remained possible, or even probable, until a source was determined. The immediate restrictions put on the CBD were quasi-level 3.
If bad luck had prevailed, Covid could have spread via a passenger sharing the student’s Uber driver, a diner sitting near her at the Red Pig, or any of the dozens of people living at the Vincent Residences who might have shared a lift button or a rubbish bin lid.
But then the dice then started rolling our way. The student lived alone. She only had a few workplace contacts. She hadn’t been to the supermarket. Neither she nor her three close contacts had left the CBD.
Then, the jackpot. Genomic sequencing revealed the source, and not only was it a known case, but the strain was identical to the serviceman’s.
Combined with the timeline of infection, it seems likely that he infected her, meaning there are no missing links in the transmission chain to unearth.
It was suggested to Covid-19 Response Minister Chris Hipkins that this was luck masquerading as competence.
And, as epidemiologist Sir David Skegg said, there’s always been a “modicum of good luck” in New Zealand’s worldleading Covid-response.
We have a line of defences to prevent Covid-19 from spreading.
But public health experts have been calling for those to be strengthened, including mandatory mask-wearing on public transport and flights at level 1 and compulsory QR scanning.
Hipkins has resisted, apparently because the public’s goodwill towards the Government response might crumble. However, Hipkins changed his mind on face masks for Auckland — with Ardern’s backing — and other centres are likely to follow.
He is still looking into the legalities of mandatory scanning. Even if it can’t really be enforced, an order would still push up the number of scanners and scans.
Only one in six people registered with the Covid Tracer app are using it.
With that kind of abysmal ratio, luck will eventually run out.