By Susan Strongman, RNZ

There are 177 cases of Covid-19 associated with the Auckland August cluster. The current number of active cases within the cluster is 55.

But somewhat confusingly, the Ministry of Health has broken sections of the large Auckland August cluster down into five of what it calls "sub-clusters". This is despite some experts arguing these classifications are not helpful, and that the cases should be referred to as several separate clusters, or an outbreak.

The sub-clusters include cases associated with the Mt Roskill Evangelical Fellowship church (33 cases), "bereavement events" (15 cases), North Shore Hospital's emergency department (3 cases), cases in the east Auckland suburb of Botany (6), and cases linked to well known general practitioner Joe Williams (5).

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None of these sub-clusters have been epidemiologically linked to the Auckland August cluster. This means contact tracers have not been able to determine when or where a person from the August cluster infected with Covid-19 came into contact with, and infected, another person from any of the sub-clusters.

Two of the sub-clusters, however, are epidemiologically linked to each other; the Mt Roskill Evangelical Fellowship sub-cluster and bereavement sub-cluster. The virus was transmitted when a member of the church visited a bereaved family, while waiting for the results of a Covid-19 test, inadvertently infecting members of the bereavement group with the virus. Among those infected were a student at St Dominic's Catholic College and a bus driver - both of whom are classified as members of the bereavement sub-cluster.

People in cars line up to be tested at the Mt Eden testing station. Photo / Alex Burton
People in cars line up to be tested at the Mt Eden testing station. Photo / Alex Burton

Genomic testing - looking at the genetic sequence of the virus - allows scientists to link cases of Covid-19 with each other, but not to identify how the case was transmitted person to person. Through genomic testing, we know that all the sub-clusters are linked to the Auckland August cluster - but we don't know how the virus was transmitted from a person in the Auckland August cluster to the first person to be infected within each sub-cluster.

Auckland August cluster:

• 177 cases total, of which 55 are active. One death.
• The origins of this cluster remain under investigation.

On August 11, a person in their 50s, who worked at the Americold coolstore in Mt Wellington, tested positive for Covid-19. Further cases of the virus were detected in the worker's colleagues and family.

On September 4, Americold staffer Alan Te Hiko, who was in his 50s, was the youngest person to die in New Zealand of the coronavirus. The origins of this cluster remain under investigation.

Mt Roskill Evangelical Fellowship sub-cluster:

• 33 cases. 17 active.
• Genomically linked to Auckland August cluster.

The sub-cluster was originally larger, but was divided in two, when cases associated with the bereavement events were classified as a sub-cluster by the Ministry of Health. The epidemiological link to the Auckland August cluster is unknown.

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Bereavement events sub-cluster:

• 15 cases. All active.
• Genomically linked to Auckland August cluster.
• Epidemiologically linked to Mt Roskill Evangelical Fellowship sub-cluster.

The virus was transmitted when a member of the Mt Roskill Evangelical Fellowship visited a bereaved family, while waiting for the results of a Covid-19 test, inadvertently infecting members of the bereavement group with the virus. Among those infected were a student at St Dominic's Catholic College and a bus driver - both of whom are classified as members of the bereavement sub-cluster.

Botany sub-cluster:

• Six cases. One active.
• Genomically linked to Auckland August cluster.

The first case in this sub-cluster was reported on August 28, and the most recent case was reported on Monday (September 14). According to the Herald, the group is made up of two households. The epidemiological link to the Auckland August cluster is unknown.

North Shore ER sub-cluster:

• Three cases. None active.
• Genomically linked to Auckland August cluster.
On 21 August, a man in his 30s arrived at North Shore Hospital with symptoms of the virus. It remains unclear how this man was infected with Covid-19.

GP sub-cluster:

• Five cases. Four recovered. One death.
• Genomically linked to Auckland August cluster.

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It remains unknown how former Cook Islands prime minister and prominent doctor Joe Williams, 82, contracted the Covid-19 infection that led to his death on September 4. Five other cases of the virus are associated with this sub-cluster, and the virus is genomically linked to the Auckland August cluster. The epidemiological link to the cluster is unknown.

The Outliers:

There are two other community cases of Covid-19 in New Zealand, which are not linked to the Auckland August cluster either genomically or epidemiologically. These cases, both now recovered, were identified in a worker at Auckland's Rydges Hotel managed isolation and quarantine facility, and in the brother of a person who visited the Hobbiton film set.