Modelling the impact of travel restrictions on COVID-19 cases in Hong Kong in early 2020.

BACKGROUND: Coronavirus Disease 2019 (COVID-19) led to pandemic that affected almost all countries in the world. Many countries have implemented border restriction as a public health measure to limit local outbreak. However, there is inadequate scientific data to support such a practice, especially in the presence of an established local transmission of the disease. OBJECTIVE: To apply a metapopulation Susceptible-Exposed-Infectious-Recovered (SEIR) model with inspected migration to investigate the effect of border restriction as a public health measure to limit outbreak of coronavirus disease 2019. METHODS: We apply a modified metapopulation SEIR model with inspected migration with simulating population migration, and incorporating parameters such as efficiency of custom inspection in blocking infected travelers in the model. The population sizes were retrieved from government reports, while the number of COVID-19 patients were retrieved from Hong Kong Department of Health and China Centre for Disease Control (CDC) data. The R0 was obtained from previous clinical studies. RESULTS: Complete border closure can help to reduce the cumulative COVID-19 case number and mortality in Hong Kong by 13.99% and 13.98% respectively. To prevent full occupancy of isolation facilities in Hong Kong; effective public health measures to reduce local R0 to below 1.6 was necessary, apart from having complete border closure. CONCLUSIONS: Early complete travel restriction is effective in reducing cumulative cases and mortality. However, additional anti-COVID-19 measures to reduce local R0 to below 1.6 are necessary to prevent COVID-19 cases from overwhelming hospital isolation facilities.

Case of "relapsing" COVID-19 in a kidney transplant recipient.

Clinical outcomes of COVID-19 vary considerably between patients. Little was known about the clinical course and optimal management of immunosuppressed patients infected with SARS-CoV-2. We report a kidney transplant recipient with COVID-19 who presented with pneumonitis and acute kidney injury (AKI). She improved after reduction of immunosuppressive treatment and had two consecutive negative reverse transcription polymerase chain reaction (RT-PCR) tests. Her respiratory tract samples turned positive again afterwards, and she was treated with lopinavir-ritonavir. She had satisfactory virological and clinical response after a prolonged disease course. This case illustrates the risk of relapse or persisting shedding of SARS-CoV-2 in immunosuppressed patients, the important role of viral load monitoring in management, the challenges in balancing the risks of COVID-19 progression and transplant rejection, and the pharmacokinetic interaction between immunosuppressive and antiviral medications.