Epidemic Surveillance of Influenza Infections:A Network-Free Strategy—Hong Kong Special Administrative Region,China,2008–2011

Introduction:The ease of coronavirus disease 2019(COVID-19)non-pharmacological interventions and the increased susceptibility during the past COVID-19 pandemic could be a precursor for the resurgence of influenza,potentially leading to a severe outbreak in the winter of 2022 and future seasons.The recent increased availability of data on Electronic Health Records(EHR)in public health systems,offers new opportunities to monitor individuals to mitigate outbreaks.Methods:We introduced a new methodology to rank individuals for surveillance in temporal networks,which was more practical than the static networks.By targeting previously infected nodes,this method used readily available EHR data instead of the contactnetwork structure.Results:We validated this method qualitatively in a real-world cohort study and evaluated our approach quantitatively by comparing it to other surveillance methods on three temporal and empirical networks.We found that,despite not explicitly exploiting the contacts’network structure,it remained the best or close to the best strategy.We related the performance of the method to the public health goals,the reproduction number of the disease,and the underlying temporal-network structure(e.g.,burstiness).Discussion:The proposed strategy of using historical records for sentinel surveillance selection can be taken as a practical and robust alternative without the knowledge of individual contact behaviors for public health policymakers.

Travel-related Importation and Exportation Risks of SARS-CoV-2 Omicron Variant in 367 Prefectures(Cities)-China,2022

Introduction:Minimizing the importation and exportation risks of coronavirus disease 2019(COVID-19)is a primary concern for sustaining the“Dynamic COVID-zero”strategy in China.Risk estimation is essential for cities to conduct before relaxing border control measures.Methods:Informed by the daily number of passengers traveling between 367 prefectures(cities)in China,this study used a stochastic metapopulation model parameterized with COVID-19 epidemic characteristics to estimate the importation and exportation risks.Results:Under the transmission scenario(R0=5.49),this study estimated the cumulative case incidence of Changchun City,Jilin Province as 3,233(95%confidence interval:1,480,4,986)before a lockdown on March 14,2022,which is close to the 3,168 cases reported in real life by March 16,2022.In a total of 367 prefectures(cities),127(35%)had high exportation risks according to the simulation and could transmit the disease to 50%of all other regions within a period from 17 to 94 days.The average time until a new infection arrives in a location in 1 of the 367 prefectures(cities)ranged from 26 to 101 days.Conclusions:Estimating COVID-19 importation and exportation risks is necessary for preparedness,prevention,and control measures of COVID-19—especially when new variants emerge.