COVID-19: Modeling the shift from elimination to mitigation in Aotearoa New Zealand

For the first eighteen months of the COVID-19 pandemic, Aotearoa New Zealand focused on an elimination strategy to stamp out transmission of SARS-CoV-2 (COVID-19). By late 2021, the country was dealing with a major outbreak of the delta variant of COVID-19 following the government's decision to transition away from the elimination strategy and move to a strategy of mitigation under the COVID Protection Framework, or "traffic light system."

To investigate how the traffic light system might be used to limit the health burden manage the tricky transition to living with the virus, researchers from COVID-19 Modeling Aotearoa developed an epidemiological model for the delta variant which included the effects of vaccination, case isolation, contact tracing and population-wide control measures.

In research released Wednesday February 1 in Royal Society Open Science, scientists found that while a strict combination of community restrictions would reduce the health burden caused by COVID-19, it would also result in long periods of national lockdowns. They also showed that increasing the number of border arrivals had a negligible effect on health burden once community transmission was widespread.

COVID-Modeling Aotearoa's Dr. Giorgia Vattiato said that while this work pre-dates the 2022 omicron outbreak, the results presented show the trade-offs between different levels of restrictions and viral spread in the community. "These are critical aspects to consider while planning for a mitigation strategy, because it is important to find a balance between trying to reduce the COVID health burden and minimizing disruption in people's lives."