Effectiveness of feedback control and the trade-off between death by COVID-19 and costs of countermeasures.

We provided a framework of a mathematical epidemic modeling and a countermeasure against the novel coronavirus disease (COVID-19) under no vaccines and specific medicines. The fact that even asymptomatic cases are infectious plays an important role for disease transmission and control. Some patients recover without developing the disease; therefore, the actual number of infected persons is expected to be greater than the number of confirmed cases of infection. Our study distinguished between cases of confirmed infection and infected persons in public places to investigate the effect of isolation. An epidemic model was established by utilizing a modified extended Susceptible-Exposed-Infectious-Recovered model incorporating three types of infectious and isolated compartments, abbreviated as SEIIIHHHR. Assuming that the intensity of behavioral restrictions can be controlled and be divided into multiple levels, we proposed the feedback controller approach to implement behavioral restrictions based on the active number of hospitalized persons. Numerical simulations were conducted using different detection rates and symptomatic ratios of infected persons. We investigated the appropriate timing for changing the degree of behavioral restrictions and confirmed that early initiating behavioral restrictions is a reasonable measure to reduce the burden on the health care system. We also examined the trade-off between reducing the cumulative number of deaths by the COVID-19 and saving the cost to prevent the spread of the virus. We concluded that a bang-bang control of the behavioral restriction can reduce the socio-economic cost, while a control of the restrictions with multiple levels can reduce the cumulative number of deaths by infection.

A new SEIAR model on small-world networks to assess the intervention measures in the COVID-19 pandemics.

A new susceptible-exposed-infected-asymptomatically infected-removed (SEIAR) model is developed to depict the COVID-19 transmission process, considering the latent period and asymptomatically infected. We verify the suppression effect of typical measures, cultivating human awareness, and reducing social contacts. As for cutting off social connections, the feasible measures encompass social distancing policy, isolating infected communities, and isolating hub nodes. Furthermore, it is found that implementing corresponding anti-epidemic measures at different pandemic stages can achieve significant results at a low cost. In the beginning, global lockdown policy is necessary, but isolating infected wards and hub nodes could be more beneficial as the situation eases. The proposed SEIAR model emphasizes the latent period and asymptomatically infected, thus providing theoretical support for subsequent research.

APASL practical recommendations for the management of hepatocellular carcinoma in the era of COVID-19.

BACKGROUND: COVID-19 has been giving the devastating impact on the current medical care system. There are quite many guidelines on COVID-19, but only a few on the management of hepatocellular carcinoma (HCC) during COVID-19 pandemic. AIMS: We develop these recommendations to preserve adequate clinical practice for the management of HCC. METHODS: Experts of HCC in the Asia-Pacific region exchanged opinions via webinar, and these recommendations were formed. RESULTS: Close contact should be minimized to reduce possible exposure of both medical staff and patients to the novel coronavirus. To prevent transmission of the virus, meticulous hygiene measures are important. With the decrease in regular medical service, the medical staff may be mobilized to provide COVID-19-related patient care. However, diagnosis and treatment of HCC should not be delayed because of COVID-19 pandemic. The management of HCC should be the same as in non-pandemic circumstances. HCC is highly malignant, thus it is recommended not to delay curative treatment such as surgery and ablation. However, a kind of triage is necessary even among patients with HCC when resources are insufficient for all to be treated. Curative treatments should be periodized and cytoreductive or non-curative treatment such as vascular interventions and systemic therapy may be postponed until it can be performed safely with sufficient resources. For patients with confirmed or suspected to be infected with the novel coronavirus, diagnosis and treatment should be postponed until the virus is eliminated or they are confirmed as not being infected with it. CONCLUSIONS: These are collection of measures implemented by front-line medical professionals. We would evolve these recommendations over time as more real-world data becomes available.