| Infectious diseases have always been a key factor threatening human health and affecting the sustainable development of society and economy.Such as COVID-19,which has been spreading since 2019;measles,which has been trying to be eliminated;and monkeypox,which has been re-emerging recently.As of April 2023,there have been more than 761 million confirmed cases and more than 6.8 million deaths worldwide.In early May 2022,a renewed outbreak of monkeypox virus(MPXV)became of great concern to public authorities worldwide,with over 70,000 confirmed cases as of October 2022.This paper aims to explore the transmission mechanism and prevention and control effect of three kinds of infectious diseases.First,to further clarify the impact mechanism of adaptive protection behavior and vaccination,we developed a new transmission model via a delay differential system,which parameterized the roles of adaptive behaviors and vaccination,and allowed to simulate the dynamic infection process among people.By validating the model with surveillance data during March 2020 and October 2021 in America,India,South Africa,Philippines,Brazil,UK,Spain and Germany,we quantified the protection effect of adaptive behaviors by different forms of activity function.The modeling results indicated that(1)the adaptive activity function can be used as a good indicator for fitting the intervention outcome,which exhibited short-term awareness in these countries,and it could reduce the total human infections by 3.68,26.16,15.23,4.23,7.26,1.65,5.51 and 7.07 times,compared with the reporting;(2)for complete prevention,the average proportions of people with immunity should be larger than 90%,92%,86%,71%,92%,84%,82% and 76% with adaptive protection behaviors,or 91%,97%,94%,77%,92%,88%,85% and 90% without protection behaviors;and(3)the required proportion of humans being vaccinated is a sub-linear decreasing function of vaccine efficiency,with small heterogeneity in different countries.Then,in order to explore the complexity between measles transmission and vaccination and reveal the effect of vaccination,we used a dynamic model to fit the dynamic transmission process of measles.The number of reported measles cases and vaccination data in Guangdong Province from 2005 to 2021 were used to verify the dynamic model,and the influence of vaccination rate was explored by numerical simulation.The interrupt time sequence model was used to evaluate the effects of different vaccination strategies.The results show that:(1)the measles outbreak in Guangdong Province was mainly concentrated in Guangzhou and Shenzhen.there was little difference in regional distribution before and after the epidemic rebound;(2)for children under two years of age,if the vaccination rate drops to 99% since Jan 2017(2016),the small(large)epidemic would begin from 2018;(3)the effect of combined immunization strategy of MV and MR may be better than that of single inoculation of MV.The short-term effect of MMR vaccination is better than other vaccines,but its long-term effect is still unclear;(4)two doses vaccine and high coverage is the key to reduce measles incidence.These findings will benefit policy-making of measles vaccination and prevention.Finally,in order to understand the early dynamics of MPXV infection,we predicted the disappearance time of MPXV DNA detection in various body fluids by using survival analysis model based on the information of clinical samples from recent monkeypox cases.The results showed that the detection time predicted by the model was consistent with the results reported in clinical cases.MPXV DNA was detected in urine for the longest time(13.5 days),followed by semen(11.4 days)and blood(10.6 days). |
