"There is no sense that any horse has bolted here."
That is how health chief Ashley Bloomfield described the risk level from the latest community outbreak - a health worker who was looking after Covid-infected mariners in the quarantine wing of Christchurch's Sudima Airport Hotel.
The risk of a surge in cases remains low even though a second Sudmina worker tested positive last night - a close contact of the health worker who hasn't had any symptoms.
So far only two locations of potential spread have been identified.
For the first - Cashmere High School - a student who is the health worker's household contact, has tested negative, and is in isolation.
The second - a Countdown supermarket in the city - wouldn't be a concern at all if the health worker had stayed home instead of going shopping a day after feeling ill. She spent an hour at the supermarket, and some 20 people who were inside at the same time have been notified via the Covid Tracer app.
The second Sudima worker has two household contacts who are both now in self-isolation.
A low risk assessment aligns with the World Health Organisation advice, which says you're most likely to catch it if you're within a metre of an infected person, especially if they are coughing or breathing heavily.
The supermarket isn't somewhere that normally requires a level of exertion that warrants huffing and puffing.
Surface contamination isn't impossible, but what is the likelihood of the worker spluttering all over the confectionery aisle?
Bloomfield compared the health worker's case with the infected Jet Park nurse who went to exercise classes and the port-related case who spent two and a half hours at The Malt pub in the North Shore.
Neither case led to further infections, even though they were exactly the kind of poorly-ventilated, heavy breathing-type scenarios from where some horses might have at least started cantering.
A more suitable comparison is the man who escaped a managed isolation hotel in Auckland and spent 20 minutes in a downtown Countdown. In that case, too, there was no further spread.
That case was also noteworthy for the changes it triggered. Health Minister Chris Hipkins demanded improvements after health officials failed to provide timely advice to Countdown, which did us all a favour by closing its doors and deep-cleaning the store off its own bat.
For the Sudima cases, identifying any gaps in infection prevention protocols are critical to improving the system. Was proper PPE worn, and worn correctly? Were surfaces properly cleaned or physical distancing practised?
More worrying is that there have been six times - and possibly seven - where these protocols have failed in recent months.
There's the August cluster of 179 cases - the source is undetermined but a border breach is likely - the maintenance worker at Rydges Hotel, the Jet Park nurse, the overseas returnee who caught Covid-19 from a shared rubbish bin lid, the port worker, and each of the two Sudima cases.
Public health expert Professor Nick Wilson described them as "border failures".
Bloomfield rejected this but appeared to miss the point when he said it was about people being Covid-free after finishing their 14-day isolation stay.
Wilson was talking about cases where an infection has spread from inside a facility into the community.
The aim of infection prevention controls is self-explanatory. They exist to prevent infections, and they fail in cases where infections aren't prevented.
Wilson's sentiment found favour with eminent epidemiologist Sir David Skegg.
"It is highly unsatisfactory that we have had six incursions of the virus across our borders in only three months," Skegg told the Herald before the second Sudima case was revealed.
"No system can be perfect, but we need to face up to the fact that these are failures of infection control. How many wake-up calls do we need?"
He also called for the release of the border system audit by Heather Simpson and Sir Brian Roche. Incredibly, Bloomfield was yet to see the report as of yesterday, even though it was finalised weeks ago.
Skegg was also less optimistic than Bloomfield about the low chances of further spread, given how stochastic the virus is.
There's a roll of the dice every time there's a community case. A wedding in Bluff led to 98 cases, for example, but none of the 94 close contacts linked to three Les Mills exercise classes caught it from the Covid-infected nurse.
"Hopefully the risk of wider spread is low, but it is too early to tell at this stage," Skegg said.
The horses are all currently accounted for, but health officials will be on high alert for any new community cases in the coming days - with a lockdown not impossible.