Binny Rachelle N, Baker Michael G, Hendy Shaun C, James Alex, Lustig Audrey, Plank Michael J, Ridings Kannan M, Steyn Nicholas
Manaaki Whenua, Lincoln, New Zealand.
Te Pūnaha Matatini: the Centre for Complex Systems and Networks, Auckland, New Zealand.
R Soc Open Sci. 2021 Nov 17;8(11):210488. doi: 10.1098/rsos.210488. eCollection 2021 Nov.
New Zealand responded to the COVID-19 pandemic with a combination of border restrictions and an Alert Level (AL) system that included strict stay-at-home orders. These interventions were successful in containing an outbreak and ultimately eliminating community transmission of COVID-19 in June 2020. The timing of interventions is crucial to their success. Delaying interventions may reduce their effectiveness and mean that they need to be maintained for a longer period. We use a stochastic branching process model of COVID-19 transmission and control to simulate the epidemic trajectory in New Zealand's March-April 2020 outbreak and the effect of its interventions. We calculate key measures, including the number of reported cases and deaths, and the probability of elimination within a specified time frame. By comparing these measures under alternative timings of interventions, we show that changing the timing of AL4 (the strictest level of restrictions) has a far greater impact than the timing of border measures. Delaying AL4 restrictions results in considerably worse outcomes. Implementing border measures alone, without AL4 restrictions, is insufficient to control the outbreak. We conclude that the early introduction of stay-at-home orders was crucial in reducing the number of cases and deaths, enabling elimination.
新西兰应对新冠疫情的措施包括边境限制以及一套警戒级别（AL）系统，其中包括严格的居家令。这些干预措施成功遏制了疫情爆发，并最终于2020年6月消除了新冠病毒的社区传播。干预措施的时机对其成功至关重要。推迟干预可能会降低其效果，并意味着需要维持更长时间。我们使用一个新冠病毒传播与控制的随机分支过程模型，来模拟新西兰2020年3月至4月疫情爆发的流行轨迹及其干预措施的效果。我们计算关键指标，包括报告的病例数和死亡数，以及在特定时间框架内消除疫情的概率。通过比较在不同干预时机下的这些指标，我们表明，改变AL4（最严格的限制级别）的时机比边境措施的时机影响要大得多。推迟AL4限制会导致结果严重恶化。仅实施边境措施而没有AL4限制，不足以控制疫情爆发。我们得出结论，早期实施居家令对于减少病例数和死亡数、实现疫情消除至关重要。
