Kyoto University School of Public Health, Yoshidakonoe cho, Sakyo-ku, Kyoto City, 6068501, Japan.
BMC Infect Dis. 2024 May 2;24(1):464. doi: 10.1186/s12879-024-09327-8.
The Japanese government has instituted border control measures against COVID-19, including entry and exit screening of people arriving from overseas. We sought to evaluate the effectiveness of the exit screening policy in Japan in reducing the risk of importing COVID-19 cases among travelers from Asian and Pacific countries.
The study period was stratified based on the timing of exit screening: (i) the control period (the pre-exit screening period from 25 October 2020 to 16 January 2021), (ii) the time period with the Alpha variant from 17 January to 10 April 2021, and (iii) the time period with the Delta variant from 2 May to 2 October 2021. Incidence data in the countries of origin were used to adjust for the risk of infection among travelers. The positivity rate of entry screening in Japan was compared among the three different study periods, adjusting for the risk of infection in the country of origin.
The adjusted relative risk of positivity was greatly reduced and substantially below the value of 1 during the Alpha variant period compared with the control period. Although the relative risks increased when comparing the Delta variant period against control, the estimate remained below 1, except for among travelers from India and Myanmar. The relative risk reduction was greatest in high-income countries, with estimates of 100% and 96% risk reduction during the Alpha and Delta variant periods, respectively, followed by upper-middle-income countries with estimates of 90% and 76%, respectively.
Even in the presence of the Alpha and Delta variants, exit screening clearly reduced the risk of infection among travelers arriving from Asian and Pacific nations. As the testing relies on the country of origin, the effectiveness varied greatly by the socioeconomic income status and epidemiological situation of those countries. Test standardization and quality assurance may be required in low- and middle-income countries.
日本政府针对 COVID-19 实施了边境管控措施，包括对从海外抵达的人员进行入境和出境筛查。我们旨在评估日本的出境筛查政策在降低来自亚洲和太平洋国家旅行者输入 COVID-19 病例风险方面的有效性。
研究期间根据出境筛查的时间进行分层：（i）对照期（2020 年 10 月 25 日至 2021 年 1 月 16 日的出境前筛查期），（ii）Alpha 变异株时期（2021 年 1 月 17 日至 4 月 10 日），（iii）Delta 变异株时期（2021 年 5 月 2 日至 10 月 2 日）。使用原籍国的发病数据来调整旅行者感染的风险。在三个不同的研究期间，通过调整原籍国的感染风险，比较了日本入境筛查的阳性率。
与对照期相比，在 Alpha 变异株时期，阳性率的调整相对风险大大降低，且明显低于 1。尽管与对照期相比，在 Delta 变异株时期的相对风险增加，但除来自印度和缅甸的旅行者外，该估计值仍低于 1。高收入国家的风险降低最大，Alpha 和 Delta 变异株时期的风险降低估计值分别为 100%和 96%，其次是中高收入国家，分别为 90%和 76%。
即使存在 Alpha 和 Delta 变异株，出境筛查显然降低了来自亚洲和太平洋国家的旅行者感染的风险。由于该检测依赖于原籍国，因此有效性因这些国家的社会经济收入状况和流行病学状况而异。中低收入国家可能需要进行测试标准化和质量保证。
