This report was delivered to the government Covid-19 steering group on November 13 2020, and this version of the report was compiled on September 17, 2021.
We use contagion network simulations to model the spread of COVID from index cases compatible with the known cases of the New Zealand Defence Force (NZDF) Cluster. We use these simulations to estimate the number of cases that might be expected in the community upon detection of a community transmission case with no epidemiological link to the NZDF cluster. Namely that of the retail worker identified on November 12th.
- We find that if the index case was Case A of the NZDF cluster then we could expect around 16 cases present in the community by the date of detection of the retail worker. If the index case was Case B of the NZDF cluster then we could expect around 9 cases present in the community by the date of detection of the retail worker.
- The above results assume completely undetected and uncontrolled spread from the index cases. Since this was not the case for the NZDF cluster, with close contacts of Cases A and B being traced, and isolating, the numbers above present a more pessimistic scenario than reality.