BODE3 Programme, University of Otago, Wellington, New Zealand.
HEIRU, University of Otago, Wellington, New Zealand.
Sci Rep. 2021 May 24;11(1):10766. doi: 10.1038/s41598-021-89807-y.
We aimed to estimate the risk of COVID-19 outbreaks associated with air travel to a COVID-19-free country [New Zealand (NZ)]. A stochastic version of the SEIR model CovidSIM v1.1, designed specifically for COVID-19 was utilised. We first considered historical data for Australia before it eliminated COVID-19 (equivalent to an outbreak generating 74 new cases/day) and one flight per day to NZ with no interventions in place. This gave a median time to an outbreak of 0.2 years (95% range of simulation results: 3 days to 1.1 years) or a mean of 110 flights per outbreak. However, the combined use of a pre-flight PCR test of saliva, three subsequent PCR tests (on days 1, 3 and 12 in NZ), and various other interventions (mask use and contact tracing) reduced this risk to one outbreak after a median of 1.5 years (20 days to 8.1 years). A pre-flight test plus 14 days quarantine was an even more effective strategy (4.9 years; 2,594 flights). For a much lower prevalence (representing only two new community cases per week in the whole of Australia), the annual risk of an outbreak with no interventions was 1.2% and had a median time to an outbreak of 56 years. In contrast the risks associated with travellers from Japan and the United States was very much higher and would need quarantine or other restrictions. Collectively, these results suggest that multi-layered interventions can markedly reduce the risk of importing the pandemic virus via air travel into a COVID-19-free nation. For some low-risk source countries, there is the potential to replace 14-day quarantine with alternative interventions. However, all approaches require public and policy deliberation about acceptable risks, and continuous careful management and evaluation.
我们旨在评估前往无 COVID-19 国家（新西兰）旅行与 COVID-19 疫情爆发相关的风险。我们使用了专门为 COVID-19 设计的 SEIR 模型 CovidSIM v1.1 的随机版本。首先，我们考虑了澳大利亚在消除 COVID-19 之前（相当于每天产生 74 例新病例）的历史数据，以及每天飞往新西兰的一班航班，并且没有采取任何干预措施。这使得疫情爆发的中位数时间为 0.2 年（模拟结果的 95%范围：3 天至 1.1 年）或平均每 110 次航班爆发一次。然而，联合使用唾液的出发前 PCR 检测、随后在新西兰进行的三次 PCR 检测（第 1、3 和 12 天）以及其他各种干预措施（戴口罩和接触者追踪），将这种风险降低到在中位数 1.5 年后爆发一次（20 天至 8.1 年）。出发前检测加 14 天隔离是更有效的策略（4.9 年；2594 次航班）。对于更低的流行率（代表澳大利亚整个地区每周只有两例新社区病例），没有干预措施的疫情爆发的年风险为 1.2%，爆发的中位数时间为 56 年。相比之下，来自日本和美国旅行者的相关风险要高得多，需要隔离或其他限制。总的来说，这些结果表明，多层干预措施可以显著降低通过航空旅行将大流行病毒输入无 COVID-19 国家的风险。对于一些低风险的来源国家，有可能用替代干预措施替代 14 天的隔离。然而，所有方法都需要公众和政策对可接受风险进行审议，并持续进行仔细的管理和评估。
