An initial set of interventions, including the closure of host and hostess clubs and voluntary limitation of non-household contact, probably greatly contributed to reducing the disease incidence of coronavirus disease (COVID-19) in Japan, but this approach must eventually be replaced by a more sustainable strategy. To characterize such a possible exit strategy from the restrictive guidelines, we quantified the next-generation matrix, accounting for high- and low-risk transmission settings. This matrix was used to project the future incidence in Tokyo and Osaka after the state of emergency is lifted, presenting multiple ‘post-emergency’ scenarios with different levels of restriction. The effective reproduction numbers (R) for the increasing phase, the transition phase and the state-of-emergency phase in the first wave of the disease were estimated as 1.78 (95% credible interval (CrI): 1.73–1.82), 0.74 (95% CrI: 0.71–0.78) and 0.63 (95% CrI: 0.61–0.65), respectively, in Tokyo and as 1.58 (95% CrI: 1.51–1.64), 1.20 (95% CrI: 1.15–1.25) and 0.48 (95% CrI: 0.44–0.51), respectively, in Osaka. Projections showed that a 50% decrease in the high-risk transmission is required to keep R less than 1 in both locations—a level necessary to maintain control of the epidemic and minimize the risk of resurgence.

最初的一系列干预措施，包括关闭招待所和女招待俱乐部以及自愿限制非家庭联系，可能在很大程度上降低了日本冠状病毒病（COVID-19）的发病率，但这种方法最终必须被替代更可持续的策略。为了从限制性指南中表征这种可能的退出策略，我们对下一代矩阵进行了量化，并考虑了高风险和低风险的传输设置。此矩阵用于预测紧急状态解除后东京和大阪的未来发生率，从而呈现出具有不同限制级别的多个“紧急情况后”场景。有效繁殖数（R）对于疾病的增加阶段，第一波疾病的过渡阶段和紧急状态阶段估计为1.78（95％可信区间（CrI）：1.73–1.82），0.74（95％CrI：0.71–东京分别为0.78）和0.63（95％CrI：0.61-0.65），分别为1.58（95％CrI：1.51-1.64），1.20（95％CrI：1.15-1.25）和0.48（95％CrI：0.44– 0.51），分别在大阪。预测表明，要使两个地点的R值均小于1，都需要将高风险传播降低50％，这是维持流行病控制并使复发风险最小化所必需的水平。