A five-compartment model of age-specific transmissibility of SARS-CoV-2

Background:The novel coronavirus,severe acute respiratory syndrome coronavirus 2(SARS-CoV-2,also called 2019-nCoV)causes different morbidity risks to individuals in different age groups.This study attempts to quantify the age-specific transmissibility using a mathematical model.Methods:An epidemiological model with five compartments(susceptible-exposed-symptomatic-asymptomatic-recovered/removed[SEIAR])was developed based on observed transmission features.Coronavirus disease 2019(COVID-19)cases were divided into four age groups:group 1,those≤14years old;group 2,those 15 to 44years old;group 3,those 45 to 64years old;and group 4,those≥65 years old.The model was initially based on cases(including imported cases and secondary cases)collected in Hunan Province from January 5 to February 19,2020.Another dataset,from Jilin Province,was used to test the model.Results:The age-specific SEIAR model fitted the data well in each age group(P<0.001).In Hunan Province,the highest transmissibility was from age group 4 to 3(median:β43=7.71×10-9;SAR43=3.86×10-8),followed by group 3 to 4(median:β34=3.07×10-9;SAR34=1.53×10-8),group 2 to 2(median:β22=1.24×10-9;SAR22=6.21×10-9),and group 3 to 1(median:β31=4.10×10-10;SAR31=2.08×10-9).The lowest transmissibility was from age group 3 to 3(median:β33=1.64×10-19;SAR33=8.19×10-19),followed by group 4 to 4(median:β44=3.66×10-17;SAR44=1.83×10-16),group 3 to 2(median:β32=1.21×10-16;SAR32=6.06×10-16),and group 1 to 4(median:β14=7.20×10-14;SAR14=3.60×10-13).In Jilin Province,the highest transmissibility occurred from age group 4 to 4(median:β43=4.27×10-8;SAR43=2.13×10-7),followed by group 3 to 4(median:β34=1.81×10-8;SAR34=9.03×10-8).Conclusions:SARS-CoV-2 exhibits high transmissibility between middle-aged(45 to 64 years old)and elderly(≥65 years old)people.Children(≤14 years old)have very low susceptibility to COVID-19.This study will improve our understanding of the transmission feature of SARS-CoV-2 in different age groups and suggest the most prevention measures should be applied to middle-aged and elderly people.

Effectiveness of potential antiviral treatments in COVID-19 transmission control:a modelling study

Background:Novel coronavirus disease 2019(COVID-19)causes an immense disease burden.Although public health countermeasures effectively controlled the epidemic in China,non-pharmaceutical interventions can neither be maintained indefinitely nor conveniently implemented globally.Vaccination is mainly used to prevent COVID-19,and most current antiviral treatment evaluations focus on clinical efficacy.Therefore,we conducted population-based simulations to assess antiviral treatment effectiveness among different age groups based on its clinical efficacy.

Relative transmissibility of shigellosis among male and female individuals:a modeling study in Hubei Province,China

Background:Developing countries exhibit a high disease burden from shigellosis.Owing to the different incidences in males and females,this study aims to analyze the features involved in the transmission of shigellosis among male(subscript m)and female(subscript f)individuals using a newly developed sex-based model.Methods:The data of reported shigellosis cases were collected from the China Information System for Disease Control and Prevention in Hubei Province from 2005 to 2017.A sex-based Susceptible-Exposed-Infectious/Asymptomatic-Recovered(SEIAR)model was applied to explore the dataset,and a sex-age-based SEIAR model was applied in 2010 to explore the sex-and age-specific transmissions.Results:From 2005 to 2017,130770 shigellosis cases(including 73981 male and 56789 female cases)were reported in Hubei Province.The SEIAR model exhibited a significant fitting effect with the shigellosis data(P<0.001).The median values of the shigellosis transmission were 2.3225×10^8 for SARmm(secondary attack rate from male to male),2.5729×10^8 for SARmf 2.7630×10^8 for SARfm,and 2.1061×10^8 for SARff.The top five mean values of the transmission relative rate in 2010(where the subscript 1 was defined as male and age<5 years,2 was male and age 6 to 59 years,3 was male and age>60 years,4 was female and age<5 years,5 was female and age 6 to 59 years,and 6 was male and age>60 years)were 5.76×10^8 forβ61;5.32×10^8 forβ31,4.01×10^8 forβ34,7.52×10^9 forβ62,and 6.04×10^9 for Conclusions:The transmissibility of shigellosis differed among male and female individuals.The transmissibility between the genders was higher than that within the genders,particularly female-to-male transmission.The most important route in children(age<5 years)was transmission from the elderly(age>60 years).Therefore,the greatest interventions should be applied in females and the elderly.