We don’t know where some of the past year's community cases came from, but Ministry of Health investigations have turned up information that can be used to combat future outbreaks. Matthew Scott reports
In a past life, the bad news buzzing of a phone notification used to be earthquakes or celebrity deaths. Nowadays, there’s a sense that at any moment, Kiwis might all receive the same message - Jacinda Ardern and Chris Hipkins on their way to the Beehive theatrette, and news of contagion imminent.
Although New Zealand recently lost the title of most Covid-resilient country in the world to Singapore thanks to their accelerated vaccine rollout, it has been a safe harbour over the last year in a world caught in a storm.
But that doesn’t mean New Zealand hasn’t been affected. Leaks from MIQ facilities and systems at the border have raised alert levels at short notice, affecting livelihoods, travel plans and our national peace of mind.
Each time this happens, the Ministry of Health promises a swift investigation into the source of the outbreak - presumably important information if we are to prevent shutting down our economy and immune systems in the worst-case scenario.
The Ministry of Health investigations into the highest-profile breaches of New Zealand’s bubble, however, never revealed the source and where the virus came from is still a mystery months later.
However, the Ministry says investigations are useful to help improve processes and reduce the chance of future outbreaks.
"Even when it is not possible to determine the exact transmission event, modes of transmission can be ruled out and information gathered to identify who might be at risk," it said.
The August cluster
It was three months after our last case of community transmission during the first wave that Kiwis got the bad news. The virus was back.
It looked like it had come from a refrigerated warehouse in Mt Wellington. Around the end of July, a worker from Americold came down with the sickness. On August 8, Director-General of Health Ashley Bloomfield confirmed the man’s family - a family of four from South Auckland - all had the virus.
At the time, nobody knew that working class residents of South Auckland being most vulnerable and exposed to the virus would become a pattern. Online abuse took on a racial bent as people placed the full blame of a global pandemic on the shoulders of one family.
But while they were the first people in this outbreak to be publicly reported as having Covid, we are still yet to discover exactly how they got it.
The Ministry of Health notes its investigation into the origin of this outbreak never yielded results.
Although genomic investigation suggested this strain came from the UK or Australia, exactly how the Americold worker became infected was never revealed.
Investigation takes multiple forms - case interviews, genetic testing, clinical judgment and examination of epidemiological context.
The team then comes up with a list of hypotheses on how Patient Zero came into contact with Covid and disproves them one by one.
The hope is that eventually one of them will be proven true and health authorities can get a clear idea of what went wrong and how to prevent it from happening again.
Yet after the August cluster, we still do not have that assurance.
Prime Minister Jacinda Ardern said it was “highly unlikely” the virus came into the country via Americold’s product, suggesting instead it was a case of “human-to-human” transmission.
Exactly where this transmission occurred is still anybody’s guess.
The Ministry of Health claims this is no cause for concern, saying the investigation was only closed once the cluster’s threat to the community was low enough.
“The purpose of a source investigation is to ensure there is minimal risk to the community of ongoing transmission,” it said. “The outbreak closure process is triggered after the risk of ongoing transmission is deemed to be low.”
The Valentine’s Day cluster
This year’s Valentine’s Day gift to Auckland was three days of Level 3 lockdown.
On the afternoon of Sunday, February 14, the Ministry of Health reported three members of a Papatoetoe family had tested positive, and the virus was back in the community.
The Ministry of Health Covid detectives were back on the case, contact tracing and genomic testing.
According to the Ministry, a clear genetic link was identified between this cluster and a traveller in MIQ who arrived in December. All cases in the February cluster were of ‘B.1.1.7 lineage’ - that is, closely related to one another.
So it became clear the virus returned to our shores via an MIQ facility, but how it escaped the lockdown hotel is murkier.
“An epidemiological chain of transmission was not found,” said the Ministry of Health - suggesting the investigation hit a snag again when it was time to zero in on where the human-to-human transmission went down.
The Ministry says the risk has been managed and the investigation provided the assurances necessary to open the country back up.
Now the trans-Tasman bubble is in business, most travellers entering the country will not be going via managed isolation. This means identifying where and when the virus re-enters the community will pose an even greater challenge.
There have already been breaches in the bubble; a man escaped the Western Australia lockdown to travel from Perth to Northland just last week. The Ministry of Health rectified the situation by sending him into managed isolation, but only after he had travelled freely out of Auckland.
In the likely event of more Covid in the community, New Zealand may not get concrete answers as to where it came from - but investigations will still likely serve up information that can reduce harm to the community.
