Kiang Mathew V, Chin Elizabeth T, Huynh Benjamin Q, Chapman Lloyd A C, Rodríguez-Barraquer Isabel, Greenhouse Bryan, Rutherford George W, Bibbins-Domingo Kirsten, Havlir Diane, Basu Sanjay, Lo Nathan C
Department of Epidemiology and Population Health, Stanford University, Stanford, CA, USA.
Department of Biomedical Data Science, Stanford University, Stanford, CA, USA.
Lancet Infect Dis. 2021 Jul;21(7):929-938. doi: 10.1016/S1473-3099(21)00134-1. Epub 2021 Mar 23.
Routine viral testing strategies for SARS-CoV-2 infection might facilitate safe airline travel during the COVID-19 pandemic and mitigate global spread of the virus. However, the effectiveness of these test-and-travel strategies to reduce passenger risk of SARS-CoV-2 infection and population-level transmission remains unknown.
In this simulation study, we developed a microsimulation of SARS-CoV-2 transmission in a cohort of 100 000 US domestic airline travellers using publicly available data on COVID-19 clinical cases and published natural history parameters to assign individuals one of five health states of susceptible to infection, latent period, early infection, late infection, or recovered. We estimated a per-day risk of infection with SARS-CoV-2 corresponding to a daily incidence of 150 infections per 100 000 people. We assessed five testing strategies: (1) anterior nasal PCR test within 3 days of departure, (2) PCR within 3 days of departure and 5 days after arrival, (3) rapid antigen test on the day of travel (assuming 90% of the sensitivity of PCR during active infection), (4) rapid antigen test on the day of travel and PCR test 5 days after arrival, and (5) PCR test 5 days after arrival. Strategies 2 and 4 included a 5-day quarantine after arrival. The travel period was defined as 3 days before travel to 2 weeks after travel. Under each scenario, individuals who tested positive before travel were not permitted to travel. The primary study outcome was cumulative number of infectious days in the cohort over the travel period without isolation or quarantine (population-level transmission risk), and the key secondary outcome was the number of infectious people detected on the day of travel (passenger risk of infection).
We estimated that in a cohort of 100 000 airline travellers, in a scenario with no testing or screening, there would be 8357 (95% uncertainty interval 6144-12831) infectious days with 649 (505-950) actively infectious passengers on the day of travel. The pre-travel PCR test reduced the number of infectious days from 8357 to 5401 (3917-8677), a reduction of 36% (29-41) compared with the base case, and identified 569 (88% [76-92]) of 649 actively infectious travellers on the day of flight; the addition of post-travel quarantine and PCR reduced the number of infectious days to 2520 days (1849-4158), a reduction of 70% (64-75) compared with the base case. The rapid antigen test on the day of travel reduced the number of infectious days to 5674 (4126-9081), a reduction of 32% (26-38) compared with the base case, and identified 560 (86% [83-89]) actively infectious travellers; the addition of post-travel quarantine and PCR reduced the number of infectious days to 3124 (2356-495), a reduction of 63% (58-66) compared with the base case. The post-travel PCR alone reduced the number of infectious days to 4851 (3714-7679), a reduction of 42% (35-49) compared with the base case.
Routine asymptomatic testing for SARS-CoV-2 before travel can be an effective strategy to reduce passenger risk of infection during travel, although abbreviated quarantine with post-travel testing is probably needed to reduce population-level transmission due to importation of infection when travelling from a high to low incidence setting.
University of California, San Francisco.
2019冠状病毒病大流行期间，针对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染的常规病毒检测策略可能有助于实现安全的航空旅行，并减轻病毒的全球传播。然而，这些检测与旅行策略降低乘客感染SARS-CoV-2风险及人群层面传播的有效性尚不清楚。
在这项模拟研究中，我们利用公开的2019冠状病毒病临床病例数据和已发表的自然史参数，对100000名美国国内航空旅客队列中的SARS-CoV-2传播进行了微观模拟，将个体分为易感染、潜伏期、早期感染、晚期感染或康复这五种健康状态之一。我们估计了SARS-CoV-2每日感染风险，对应每100000人中有150例每日感染发病率。我们评估了五种检测策略：（1）出发前3天内进行前鼻聚合酶链反应（PCR）检测；（2）出发前3天内及抵达后5天进行PCR检测；（3）旅行当天进行快速抗原检测（假设在活跃感染期间灵敏度为PCR的90%）；（4）旅行当天进行快速抗原检测并在抵达后5天进行PCR检测；（5）抵达后5天进行PCR检测。策略2和4包括抵达后5天的隔离期。旅行期定义为旅行前3天至旅行后2周。在每种情况下，旅行前检测呈阳性的个体不允许旅行。主要研究结局是旅行期间该队列在未隔离或检疫情况下的累积感染天数（人群层面传播风险），关键次要结局是旅行当天检测出的感染人数（乘客感染风险）。
我们估计，在100000名航空旅客队列中，在无检测或筛查的情况下，将有8357（95%不确定区间6144 - 12831）个感染日，旅行当天有649（505 - 950）名活跃感染乘客。旅行前PCR检测将感染天数从8357天减少至5401天（3917 - 8677），与基础情况相比减少了36%（29 - 41），并在飞行当天识别出649名活跃感染旅客中的569名（88% [76 - 92]）；增加旅行后检疫和PCR检测后，感染天数减少至2520天（1849 - 4158），与基础情况相比减少了70%（64 - 75）。旅行当天进行快速抗原检测将感染天数减少至5674天（4126 - 9081），与基础情况相比减少了32%（26 - 38），并识别出560名（86% [83 - 89]）活跃感染旅客；增加旅行后检疫和PCR检测后，感染天数减少至3124天（2356 - 4），与基础情况相比减少了63%（58 - 66）。仅旅行后PCR检测将感染天数减少至4851天（3714 - 7679），与基础情况相比减少了42%（35 - 49）。
旅行前对SARS-CoV-2进行常规无症状检测可能是降低旅行期间乘客感染风险的有效策略，不过，从高发病率地区前往低发病率地区旅行时，可能需要缩短隔离期并进行旅行后检测，以降低因输入性感染导致的人群层面传播。
加利福尼亚大学旧金山分校。
