Epidemiology of Hand, Foot, and Mouth Disease Before and After the Introduction of Enterovirus 71 Vaccines in Chengdu, China, 2009-2018

The Milk of Cows Immunized with Trivalent Inactivated Vaccines Provides Broad-Spectrum Passive Protection against Hand, Foot, and Mouth Disease in Neonatal Mice

Hand, foot, and mouth disease (HFMD) is a contagious viral infection predominantly affecting infants and young children, caused by multiple enteroviruses, including Enterovirus 71 (EV71), Coxsackievirus A16 (CA16), Coxsackievirus A10 (CA10), and Coxsackievirus A6 (CA6). The high pathogenicity of HFMD has garnered significant attention. Currently, there is no specific treatment or broad-spectrum preventive measure available for HFMD, and existing monovalent vaccines have limited impact on the overall incidence or prevalence of the disease. Consequently, with the emergence of new viral strains driven by vaccine pressure, there is an urgent need to develop strategies for the rapid response and control of new outbreaks. In this study, we demonstrated the broad protective effect of maternal antibodies against three types of HFMD by immunizing mother mice with a trivalent inactivated vaccine targeting EV71, CA16, and CA10, using a neonatal mouse challenge model. Based on the feasibility of maternal antibodies as a form of passive immunization to prevent HFMD, we prepared a multivalent antiviral milk by immunizing dairy cows with the trivalent inactivated vaccine to target multiple HFMD viruses. In the neonatal mouse challenge model, this immunized milk exhibited extensive passive protection against oral infections caused by the three HFMD viruses. Compared to vaccines, this strategy may offer a rapid and broadly applicable approach to providing passive immunity for the prevention of HFMD, particularly in response to the swift emergence and spread of new variants.

Effectiveness of enterovirus A71 vaccine against pediatric HFMD and disease profile of post-vaccination infection

BACKGROUND

Vaccination has been proven effective against infection with enterovirus A71 (EV-A71) in clinical trials, but vaccine effectiveness in real-world situations remains incompletely understood. Furthermore, it is not clear whether previous vaccination will result in symptom attenuation among post-vaccinated cases.

METHODS

Based on long-term data extracted from the only designed referral hospital for infectious diseases, we used a test-negative case-control design and multivariate logistic regression models to analyze the effectiveness of EV-A71 vaccine against hand, foot and mouth disease (HFMD). And then, generalized linear regression models were used to evaluate the associations between prior vaccination and disease profiles.

RESULTS

We selected 4883 inpatients for vaccine efficacy estimations and 2188 inpatients for disease profile comparisons. Vaccine effectiveness against EV-A71-induced HFMD for complete vaccination was 63.4 % and 51.7 % for partial vaccination. The vaccine effectiveness was higher among cases received the first dose within 12 months. No protection was observed against coxsackievirus (CV) A6-, CV-A10- or CV-A16-associated HFMD among children regardless of vaccination status. Completely vaccinated cases had shorter hospital stay and disease course compared to unvaccinated cases (P < 0.05).

CONCLUSIONS

These findings reiterate the need to continue the development of a multivalent vaccine or combined vaccines, and have implications for introducing optimized vaccination strategies.

Non-Polio Enterovirus Surveillance in the Ural Federal District and Western Siberia, 2022: Is There a Need for a Vaccine?

Human non-polio enteroviruses (NPEVs) are the etiological agents involved in most cases of hand-foot-and-mouth disease (HFMD), herpangina and aseptic meningitis. Information on the epidemiology profiles of NPEV in the Ural Federal District and Western Siberia is very limited, with no published data available. The aim of this study is to describe NPEV incidence in the Ural Federal District and Western Siberia among patients with different forms of non-polio enterovirus infections (NPEVIs) during 2022, stratified by age and clinical manifestations. A total of 265 samples that tested positive for NPEV using a polymerase chain reaction (PCR) were genotyped by semi-nested PCR for the VP1 gene. The results showed that 21 genotypes were identified among patients in this study. CVA6 was the most common genotype for HFMD. CVA6, along with CVA10, accounted for the majority of herpangina cases, while CVA9 was implicated in most meningitis cases. Sequence and phylogenetic analysis showed that nearly all of the CVA6 strains identified in this study displayed a close genetic relationship to strains identified in other cities in Russia and strains from China. NPEV surveillance allows for monitoring the circulation of clinically relevant genotypes, resulting in continuous data about NPEV epidemiology. This is important for improving case prevention, diagnosis and guiding clinical management.

Molecular epidemiology and clinical characteristics of enteroviruses associated HFMD in Chengdu, China, 2013-2022

OBJECTIVES

This study aims to investigate molecular epidemiology and clinical characteristics of enterovirus associated hand-foot-mouth disease (HFMD) in Chengdu, China, 2013-2022. Monitoring the molecular epidemiology and clinical features of HFMD for up to 10 years may provide some ideas for future protection and control measures.

METHODS

We conducted a retrospective analysis of the medical records of all patients with laboratory-confirmed HFMD-related enterovirus infection at the West China Second University Hospital from January 2013 to December 2022. We described the characteristics in serotype, age, sex distribution and hospitalization of enterovirus infection cases using data analysis and graphic description.

RESULTS

A total of 29,861 laboratory-confirmed cases of HFMD-related enterovirus infection were reported from 2013 to 2022. There was a significant reduction in the number and proportion of EV-A71 cases after 2016, from 1713 cases (13.60%) in 2013-2015 to 150 cases (1.83%) in 2017-2019. During the COVID-19 pandemic, EV-A71 cases even disappeared. The proportion of CV-A16 cases decreased from 13.96% in 2013-2015 to 10.84% in 2017-2019 and then to 4.54% in 2020-2022. Other (non-EV-A71 and non-CV-A16) serotypes accounted for 95.45% during 2020-2022, with CV-A6 accounting for 50.39% and CV-A10 accounting for 10.81%. Thus, CV-A6 and CV-A10 became the main prevalent serotypes. Furthermore, There was no significant difference in the enterovirus prevalence rate between males and females. The hospitalization rate of EV-A71 patients was higher that of other serotypes. In general, the proportion of HFMD hospitalizations caused by other pathogens except for EV-A71, CV-A16, CV-A10 and CV-A16 was second only to that caused by EV-A71. The proportion of children over 4 years old infected with enterovirus increased.

CONCLUSION

The incidence of HFMD associated with enterovirus infection has decreased significantly and CV-A6 has been the main pathogen of HFMD in Chengdu area in recent years. The potential for additional hospitalizations for other untested enterovirus serotypes suggested that attention should also be paid to the harms of infections with unknown enterovirus serotypes. Children with HFMD were older. The development of new diagnostic reagents and vaccines may play an important role in the prevention and control of enterovirus infection.

Evaluation of models for multi-step forecasting of hand, foot and mouth disease using multi-input multi-output: A case study of Chengdu, China

BACKGROUND

Hand, foot and mouth disease (HFMD) is a public health concern that threatens the health of children. Accurately forecasting of HFMD cases multiple days ahead and early detection of peaks in the number of cases followed by timely response are essential for HFMD prevention and control. However, many studies mainly predict future one-day incidence, which reduces the flexibility of prevention and control.

METHODS

We collected the daily number of HFMD cases among children aged 0-14 years in Chengdu from 2011 to 2017, as well as meteorological and air pollutant data for the same period. The LSTM, Seq2Seq, Seq2Seq-Luong and Seq2Seq-Shih models were used to perform multi-step prediction of HFMD through multi-input multi-output. We evaluated the models in terms of overall prediction performance, the time delay and intensity of detection peaks.

RESULTS

From 2011 to 2017, HFMD in Chengdu showed seasonal trends that were consistent with temperature, air pressure, rainfall, relative humidity, and PM10. The Seq2Seq-Shih model achieved the best performance, with RMSE, sMAPE and PCC values of 13.943~22.192, 17.880~27.937, and 0.887~0.705 for the 2-day to 15-day predictions, respectively. Meanwhile, the Seq2Seq-Shih model is able to detect peaks in the next 15 days with a smaller time delay.

CONCLUSIONS

The deep learning Seq2Seq-Shih model achieves the best performance in overall and peak prediction, and is applicable to HFMD multi-step prediction based on environmental factors.

Influence of social and meteorological factors on hand, foot, and mouth disease in Sichuan Province

BACKGROUND

Hand, foot and mouth disease (HFMD) caused by a variety of enteroviruses remains a major public health problem in China. Previous studies have found that social factors may contribute to the inconsistency of the relationship patterns between meteorological factors and HFMD, but the conclusions are inconsistent. The influence of social factors on the association between meteorology and HFMD is still less well understood. We aimed to analyze whether social factors affected the effect of meteorological factors on HFMD in Sichuan Province.

METHOD

We collected daily data on HFMD, meteorological factors and social factors in Sichuan Province from 2011 to 2017. First, we used a Bayesian spatiotemporal model combined with a distributed lag nonlinear model to evaluate the exposure-lag-response association between meteorological factors and HFMD. Second, by constructing the interaction of meteorological factors and social factors in the above model, the changes in the relative risk (RR) under different levels of social factors were evaluated.

RESULTS

The cumulative exposure curves for average temperature, relative humidity, and HFMD were shaped like an inverted "V" and a "U" shape. As the average temperature increased, the RR increased and peaked at 19 °C (RR 1.020 [95% confidence interval CI 1.004-1.050]). The urbanization rate, per capita gross domestic product (GDP), population density, birth rate, number of beds in health care centers and number of kindergartens interacted with relative humidity. With the increase in social factors, the correlation curve between relative humidity and HFMD changed from an "S" shape to a "U" shape.

CONCLUSIONS

Relative humidity and average temperature increased the risk of HFMD within a certain range, and social factors enhanced the impact of high relative humidity. These results could provide insights into the combined role of environmental factors in HFMD and useful information for regional interventions.

Children with severe enterovirus A71 infection

BACKGROUND

There are few reports on the timing of onset and the symptoms of enterovirus A71 (EV-A71) infection, which can easily be misdiagnosed. This study aimed to explore the clinical characteristics of children with severe EV-A71 infection.

METHODS

This retrospective observational study included children with severe EV-A71 infection admitted to Hebei Children's Hospital between January 2016 and January 2018.

RESULTS

A total of 101 patients were included: 57 males (56.4%) and 44 females (43.6%). They were 1-13 years of age. The symptoms were fever in 94 patients (93.1%), rash in 46 (45.5%), irritability in 70 (69.3%), and lethargy in 56 (55.4%). There were 19 (59.3%) patients with abnormal neurological magnetic resonance imaging [pontine tegmentum (n = 14, 43.8%), medulla oblongata (n = 11, 34.4%), midbrain (n = 9, 28.1%), cerebellum and dentate nucleus (n = 8, 25.0%), basal ganglia (n = 4, 12.5%), cortex (n = 4, 12.5%), spinal cord (n = 3, 9.3%), and meninges (n = 1, 3.1%)]. There was a positive correlation between the ratio of neutrophil count and white blood cell count in cerebrospinal fluid in the first 3 days of the disease (r = 0.415, P < 0.001).

CONCLUSION

The clinical symptoms of EV-A71 infection are fever and/or skin rash, irritability, and lethargy. Some patients have abnormal neurological magnetic resonance imaging. The white blood cell count in the cerebrospinal fluid of children with EV-A71 infection may increase alongside neutrophil counts.

Associations between ambient air pollutants and childhood hand, foot, and mouth disease in Sichuan, China: a spatiotemporal study

Hand, foot, and mouth disease (HFMD) is a major public health concern in the Asia-Pacific region. Previous studies have implied that ambient air pollution may affect the incidence of HFMD, but the results among different regions are inconsistent. We aimed to deepen the understanding of the associations between air pollutants and HFMD by conducting a multicity study. Daily data on childhood HFMD counts and meteorological and ambient air pollution (PM_2.5, PM₁₀, NO₂, CO, O₃, and SO₂) concentrations in 21 cities in Sichuan Province from 2015 to 2017 were collected. A spatiotemporal Bayesian hierarchical model framework was established, and then a distributed lag nonlinear models (DLNMs) was constructed to reveal exposure-lag-response relationships between air pollutants and HFMD while controlling for spatiotemporal effects. Furthermore, given the differences in the levels and seasonal trends of air pollutants between the basin region and plateau region, we explored whether these associations varied between different areas (basin and plateau). The associations between air pollutants and HFMD were nonlinear, with different lag responses. Low NO₂ concentrations and both low and high PM_2.5 and PM₁₀ concentrations were associated with a decreased risk of HFMD. No significant associations between CO, O₃, and SO₂ and HFMD were found. The associations between air pollutant concentrations and HFMD were different between the basin and plateau regions. Our study revealed associations between PM_2.5, PM₁₀, and NO₂ concentrations and HFMD, deepening the understanding of the relationships between air pollutants and HFMD. These findings provide evidence to support the formulation of relevant prevention measures and the establishment of an early warning system.

Suppression of innate and acquired immunity in severe hand foot and mouth disease caused by EV71 infections in children

Hand, foot, and mouth disease (HFMD) is a common children infectious disease caused by human enteroviruses. Most of the cases have minimal symptoms, however, some patients may develop serious neurological, cardiac complications, or even death. The pathological mechanism leading to severe HFMD is not clearly understood, and the immunological status of the individual patient may play an important role. Transcriptomes of peripheral blood mononuclear cells from EV71-infected patients (n = 45) and healthy controls (n = 36) were examined. Immune pathways were up-regulated in patients with mild disease symptoms (n = 11, M) compared to the healthy controls (n = 36, H), demonstrating an effective anti-viral response upon EV71 infection. However, in patients with severe symptoms (n = 23, S) as well as severe patients following treatment (n = 11, A), their innate and acquired immune pathways were down-regulated, indicating a global immunity suppression. Such immune suppression characteristics could thus provide an opportunity for early EV-71 infection prognosis prediction. Based on our cohort, an SVM model using RNA-seq expression levels of five genes (MCL1, ZBTB37, PLEKHM1P, IFNAR2 and YEATS2) was developed and achieved a high ROC-AUC (91·3%) in predicting severe HFMD. Meanwhile, qPCR fold-changes method was performed based three genes (MCL1, IFNAR2 and YEATS2) on additional cohort. This qPCR method achieved a ROC-AUC of 78.6% in predicting severe HFMD, which the patients could be distinguished in 2-3 h. Therefore, our models demonstrate the possibility of HFMD severity prediction based on the selected biomarkers that predict severe HFMD effectively.

PLX8394, a RAF inhibitor, inhibits enterovirus 71 replication by blocking RAF/MEK/ERK signaling

Enterovirus 71 (EV71) poses a serious threat to human health, with scattered outbreaks worldwide. There are several vaccines against a few EV71 strains but no efficient drug for the treatment of EV71 infection. Therefore, it is urgent and of significance to develop anti-EV71 drugs. Here, we found that PLX8394, a RAF inhibitor, possesses high antiviral activity against EV71 in vitro, being superior to the traditional clinical drug ribavirin. Moreover, PLX8394 exhibits broad-spectrum antiviral activity against enteroviruses. Notably, in a suckling mouse model, PLX8394 provided a 70% protection rate for EV71-infected mice, reduced the viral load in liver and heart tissues, and relieved the inflammatory response. A mechanistic study showed that PLX8394 inhibited EV71 by suppressing the RAF/MEK/ERK signaling pathway. Thus, PLX8394 lays a foundation for the development of new drugs against EV71.

Disease burden in patients with severe hand, foot, and mouth disease in Jiangsu Province: a cross-sectional study

This study aimed to estimate the disease burden and health-related quality of life (HRQOL) among patients with severe hand, foot, and mouth disease (HFMD) in Jiangsu Province, China. We analyzed the surveillance data of HFMD cases in Jiangsu Province from 2009 to 2020. Moreover, a cross-sectional study was conducted in Nanjing and Suzhou, China, between January 2017 and May 2018. Patients with severe HFMD and their parents were recruited from selected hospitals. Questionnaires and hospital management systems were used to collect data on direct economic burden. The HRQOL of children was assessed using the TNO-AZL Preschool Quality of Life (TAPQOL) scale. A total of 1,348,737 confirmed cases of HFMD were reported to the NNDRS in Jiangsu province during 2009-2020. Of these, 9,622 were severe cases, with 62 (.64%) of these being fatal. From January 2017 to May 2018, data was collected from 362 severe HFMD cases using a structured questionnaire. The median per capita direct economic burden was RMB 16142.88, and was associated with the region and length of hospital stay (P < .05). The direct economic burden for all cases of severe HFMD in Jiangsu province between 2017 and 2018 was approximately RMB 16.64 million. Finally, the median (IQR) of the TAPQOL scale for children with severe HFMD was 69.23 (56.20, 82.27). Severe HFMD infection is a relatively large burden for individuals, and the burden of EV-A71 infection was seen to be even greater for the population. Prevention of severe HFMD should strengthen hygiene habits and targeted measures for EV-A71 vaccination.

Trend of hand, foot, and mouth disease from 2010 to 2021 and estimation of the reduction in enterovirus 71 infection after vaccine use in Zhejiang Province, China

Background

Zhejiang, ranked in the top three in HFMD (hand, foot, and mouth disease) incidence, is located in the Yangtze River Delta region of southeast China. Since 2016, the EV71 vaccine has been promoted in Zhejiang Province. This study aimed to investigate the trend and seasonal variation characteristics of HFMD from 2010 to 2021 and estimate the reduction in enterovirus 71 infection after vaccine use.

Methods

The data on HFMD cases in Zhejiang Province from January 2010 to December 2021 were obtained from this network system. Individual information on cases and deaths was imported, and surveillance information, including demographic characteristics and temporal distributions, was computed by the system. The Joinpoint regression model was used to describe continuous changes in the incidence trend. The BSTS (Bayesian structural time-series models) model was used to estimate the monthly number of cases from 2017 to 2021 based on the observed monthly incidence during 2010–2016 by accounting for seasonality and long-term trends. The seasonal variation characteristics of HFMD pathogens were detected by wavelet analysis.

Results

From 2010 to 2021, the annual incidence rate fluctuated between 98.81 cases per 100,000 in 2020 and 435.63 cases per 100,000 in 2018, and 1711 severe HFMD cases and 106 fatal cases were reported in Zhejiang Province, China. The annual percent change (APC) in EV71 cases was -30.72% (95% CI: -45.10 to -12.50) from 2016 to 2021. The wavelet transform of total incidence and number of cases of the three pathogens all showed significant periodicity on the 1-year scale. The average 2-year scale periodicity was significant for the total incidence, EV71 cases and Cox A16 cases, but the other enterovirus cases showed significant periodicity on the 30-month scale. The 6-month scale periodicity was significant for the total incidence, EV71 case and Cox A16 case but not for the other enteroviruses case. The relative error percentage of the performance of the BSTS model was 0.3%. The estimated number of cases from 2017 to 2021 after the EV-A71 vaccines were used was 9422, and the reduction in the number of cases infected with the EV71 virus was 73.43% compared to 70.80% when the impact of the COVID-19 epidemic in 2020 was excluded.

Conclusions

Since 2010, the incidence of EV71 infections has shown an obvious downward trend. All types of viruses showed significant periodicity on the 1-year scale. The periodicity of the biennial peak is mainly related to EV71 and Cox A16 before 2017 and other enteroviruses since 2018. The half-year peak cycle of HFMD was mainly caused by EV71 and Cox A6 infection. The expected incidence will be 2.76 times(include the cases of 2020) and 2.43 times(exclude the cases of 2020) higher than the actual value assuming that the measures of vaccination are not taken. EV71 vaccines are very effective and should be administered in the age window between 5 months and 5 years.

Effect of enterovirus 71 vaccination on the epidemiological characteristics and etiology in hospitalized children with hand-foot-and-mouth disease: A retrospective study from a tertiary children's hospital

Enterovirus 71 (EV71) vaccine for hand-foot-and-mouth disease (HFMD) prevention has been available for several years. However, as a new vaccine, the impact of EV71 vaccination on the epidemiology and etiology of HFMD is currently unclear. The purpose of this study was to compare and analyze the changes of epidemiological characteristics and etiology of HFMD patients after the introduction of EV71 vaccine. The data of hospitalized children with HFMD from 2014 to 2020 were collected from the case record department of a tertiary children hospital of Anhui Province. The changes of epidemiological characteristics, time distribution, disease severity and enterovirus serotypes in hospitalized children were analyzed. A total of 7373 cases of HFMD were reported during 2014 to 2020, including 634 (8.6%) severe cases. The number of cases reached the peak in 2016 (n = 1783) and decreased gradually after EV71 vaccination. The results of etiological test showed the positive rate was 80.5%, in which EV71 accounted for 1599 (21.7%) and CV-A16 accounted for 1028 (13.9%) respectively. The number of patients showed a bimodal distribution throughout the year, which were April to June and October to November. The age distribution changed significantly following the introduction of EV71 vaccine. The proportion of 1-year-old group of post-vaccination was significantly higher than that of pre-vaccination (61.9% vs 50.8%, P < .001). The proportion of HFMD caused by EV71 and severe cases decreased significantly after the vaccination (P < .001 for both). While the comparison of epidemiological characteristics and enterovirus serotypes between unvaccinated and vaccinated cases during 2017 to 2020 showed no significant difference. The dominant enterovirus serotypes of hospitalized HFMD changed significantly after the introduction of EV71 vaccine. The proportion of severe cases decreased significantly after the vaccination, but EV71 was still a major pathogen in patients with severe HFMD. More age-appropriate children are recommended to get vaccinated to establish stronger herd immunity in the population.

Molecular epidemiology and clinical features of hand, foot and mouth disease requiring hospitalization after the use of enterovirus A71 inactivated vaccine in Chengdu, China, 2017-2022: a descriptive study

Three inactivated enterovirus A71 (EV-A71) vaccines have been widely vaccinated among children in the targeted age group in mainland China since mid-2016. However, comprehensive virological surveillance of hand, foot and mouth disease (HFMD) over multiple years after the use of EV-A71 vaccines has rarely been conducted. Using long-term data extracted from the Public Health and Clinical Center of Chengdu, we described the clinical, aetiological, and epidemiological characteristics of HFMD inpatients after the use of EV-A71 vaccines from 2017 through 2022. A total of 5115 patients were selected for analysis with a male-to-female ratio of 1.63:1 and were mostly under 5 years of age (97.6%). Among these cases, 4.3% presented with severe symptoms, and 4.1% of severe cases experienced significant complications. EV-A71 was no longer the major serotype for laboratory-confirmed HFMD, responsible for 15.6% of severe cases and 1.2% of mild cases. A significant downwards trend of EV-A71 infections was observed after the use of EV-A71 vaccines (P for trend < 0.001). Coxsackievirus A6 was the predominant pathogen, accounting for 63.5% of mild cases and 36.2% of severe cases. Coxsackievirus A10 (CV-A10) and A16 were sporadically detected, and an upwards trend was observed in the proportion of CV-A10 infections. This study provides baseline molecular epidemiology for the evaluation of EV-A71 vaccination impact and potential serotype replacement based on HFMD inpatients. Additional nationwide and population-based epidemiologic and serologic studies are essential to elucidate HFMD dynamics after the use of EV-A71 vaccines, and to inform public health authorities to introduce optimized intervention strategies.

Spatiotemporal cluster patterns of hand, foot, and mouth disease at the province level in mainland China, 2011–2018

Although three monovalent EV-A71 vaccines have been launched in mainland China since 2016, hand, foot, and mouth disease (HFMD) still causes a considerable disease burden in China. Vaccines’ use may change the epidemiological characters of HFMD. Spatial autocorrelation analysis and space-time scan statistics analysis were used to explore the spatiotemporal distribution pattern of this disease at the provincial level in mainland China. The effects of meteorological factors, socio-economic factors, and health resources on HFMD incidence were analyzed using Geodetector. Interrupted time series (ITS) was used to analyze the impact of the EV-A71 vaccine on the incidence of HFMD. This study found that the median annual incidence of HFMD was 153.78 per 100,000 (ranging from 120.79 to 205.06) in mainland China from 2011 to 2018. Two peaks of infections were observed per year. Children 5 years and under were the main morbid population. The spatial distribution of HFMD was presented a significant clustering pattern in each year (P<0.001). The distribution of HFMD cases was clustered in time and space. The range of cluster time was between April and October. The most likely cluster appeared in the southern coastal provinces (Guangxi, Guangdong, Hainan) from 2011 to 2017 and in the eastern coastal provinces (Shanghai, Jiangsu, Zhejiang) in 2018. The spatial heterogeneity of HFMD incidence could be attributed to meteorological factors, socioeconomic factors, and health resource. After introducing the EV-A71 vaccine, the instantaneous level of HFMD incidence decreased at the national level, and HFMD incidence trended downward in the southern coastal provinces and increased in the eastern coastal provinces. The prevention and control policies of HFMD should be adapted to local conditions in different provinces. It is necessary to advance the EV-A71 vaccination plan, expand the vaccine coverage and develop multivalent HFMD vaccines as soon as possible.

An Easy-to-Use Public Health-Driven Method (the Generalized Logistic Differential Equation Model) Accurately Simulated COVID-19 Epidemic in Wuhan and Correctly Determined the Early Warning Time

Introduction

Modeling on infectious diseases is significant to facilitate public health policymaking. There are two main mathematical methods that can be used for the simulation of the epidemic and prediction of optimal early warning timing: the logistic differential equation (LDE) model and the more complex generalized logistic differential equation (GLDE) model. This study aimed to compare and analyze these two models.

Methods

We collected data on (coronavirus disease 2019) COVID-19 and four other infectious diseases and classified the data into four categories: different transmission routes, different epidemic intensities, different time scales, and different regions, using R2 to compare and analyze the goodness-of-fit of LDE and GLDE models.

Results

Both models fitted the epidemic curves well, and all results were statistically significant. The R2 test value of COVID-19 was 0.924 (p &lt; 0.001) fitted by the GLDE model and 0.916 (p &lt; 0.001) fitted by the LDE model. The R2 test value varied between 0.793 and 0.966 fitted by the GLDE model and varied between 0.594 and 0.922 fitted by the LDE model for diseases with different transmission routes. The R2 test values varied between 0.853 and 0.939 fitted by the GLDE model and varied from 0.687 to 0.769 fitted by the LDE model for diseases with different prevalence intensities. The R2 test value varied between 0.706 and 0.917 fitted by the GLDE model and varied between 0.410 and 0.898 fitted by the LDE model for diseases with different time scales. The GLDE model also performed better with nation-level data with the R2 test values between 0.897 and 0.970 vs. 0.731 and 0.953 that fitted by the LDE model. Both models could characterize the patterns of the epidemics well and calculate the acceleration weeks.

Conclusion

The GLDE model provides more accurate goodness-of-fit to the data than the LDE model. The GLDE model is able to handle asymmetric data by introducing shape parameters that allow it to fit data with various distributions. The LDE model provides an earlier epidemic acceleration week than the GLDE model. We conclude that the GLDE model is more advantageous in asymmetric infectious disease data simulation.

Changing epidemiology of hand, foot, and mouth disease in China, 2013-2019: a population-based study

Background

Hand, foot, and mouth disease (HFMD) is an important public health problem. A monovalent EV-A71 vaccine was launched in China in 2016. Previous studies showed that inactivated monovalent EV-A71 vaccines were highly efficient against HFMD associated with EV-A71 but not against HFMD with other etiologies, leading to a hypothesis that the introduction of EV-A71 vaccines might change the pathogen spectrum and epidemiological trend of HFMD. In this study, we described for the first time the changing epidemiological characteristics of HFMD after the launch of the EV-A71 vaccine.

Methods

We extracted individual-based epidemiological data on HFMD cases reported to the Chinese Center for Disease Control and Prevention between January 2013 and December 2019. We described the changing epidemiological characteristics of HFMD before and after vaccine launch according to the distribution of diseases characteristics (demographic, temporal, and geographical) and evaluated the potential changes in risk factors of severe patients. All analyses were stratified by the phase before and after vaccine launch, and by enterovirus serotype.

Findings

During 2013-2019, 15,316,710 probable cases of HFMD were reported. Of these, 787,197 (5·1%) were laboratory confirmed and 76,982 (0·5%) were severe. After the launch of the EV-A71 vaccine, the median age of HFMD patients infected with EV-A71 increased from 2·24 years (IQR:1·43, 3·56) to 2·81 years (IQR:1·58, 4·01). The proportion of patients less than 3 years of age decreased while the proportion of patients 3-5 years of age increased. There was a large decrease (60·7%) in the proportion of severe cases as well as a decline (28·3%) in HFMD patients infected with EV-A71. After the launch of the EV-A71 vaccine, the severe illness rate and mortality rate of HFMD patients in all age groups has decreased sharply, 62·20% and 83·78% respectively. The timing of the HFMD epidemic peak was delayed (1-2 months) . After the launch of EV-A71 vaccine, the risk of becoming a severe case for EV-A71 serotype was decreased, whereas that risk was instead increased for CV-A16 (from 0·17 (95% CI:0·16, 0·18) to 0·23 (95% CI:0·21, 0·25)) and other enterovirus compared to EV-A71 (from 0·38 (95% CI:0·37, 0·39) to 0·58 (95% CI:0·56, 0·61)). The longer the time from onset to diagnosis, the higher was the risk of being a severe case, but the effect size was decreased.

Interpretation

The introduction of the EV-A71 vaccine has effectively reduced the proportion of severe HFMD cases and mortality, but changes to the dominant serotypes should be closely monitored. Development of multivalent vaccines to avoid an increased case burden due to other enteroviruses is greatly needed.

Funding

This research was supported by the National Natural Science Foundation of China (81973102, 81773487), Public Health Talents Training Program of Shanghai Municipality (GWV-10.2-XD21), the 5th Three-year Action Program of Shanghai Municipality for Strengthening the Construction of Public Health System (GWV-10.1-XK05), the Major Project of Scientific and Technical Winter Olympics from National Key Research and Development Program of China (2021YFF0306000), 13th Five-Year National Science and Technology Major Project for Infectious Diseases (2018ZX10725-509) and Key projects of the PLA logistics Scientific research Program (BHJ17J013).

Coxsackievirus B5 virus-like particle vaccine exhibits greater immunogenicity and immunoprotection than its inactivated counterpart in mice

Coxsackievirus B group 5 (CVB5) represents one of the major pathogens that cause diseases such as hand, foot and mouth disease (HFMD) and aseptic meningitis et al. Currently, no specific drugs and vaccines are available, and a safe and effective CVB5 vaccine is of great value for control of the diseases. In this study, CVB5 P1 precursor and 3CD protease were co-expressed in Sf9 cells by using a baculovirus expression system. The P1 was processed by 3CD and self-assembled into CVB5 virus-like particles (VLPs). VP1 and VP3 capsid proteins of CVB5 could be detected by SDS-PAGE and Western blotting. Transmission electron microscopy revealed that the CVB5 VLPs were spherical particles with a diameter of about 30 nm, mimicking wild-type CVB5 virus. Our study showed that the total IgG and neutralizing antibodies induced by CVB5 VLPs were higher than those induced by inactivated vaccine. More importantly, the CVB5 VLPs conferred full protection to the CVB5-challenged suckling mice via passive immunity while protection efficiency of the inactivated vaccine was only 80%. The CVB5 VLPs vaccine could protect the limb muscles, brain, and heart tissues of suckling mice from CVB5-induced damage. These results demonstrated that the CVB5 VLPs vaccine possessed stronger immunogenicity and provided more robust immunoprotection than the inactivated CVB5 vaccine, suggesting that the CVB5 VLPs promise to be a CVB5 vaccine candidate in future.

Viral determinants that drive Enterovirus-A71 fitness and virulence

Hand, Foot and Mouth Disease (HFMD) is usually a self-limiting, mild childhood disease that is caused mainly by Coxsackie virus A16 (CVA16) and Enterovirus A71 (EV-A71), both members of the Picornaviridae family. However, recurring HFMD outbreaks and epidemics due to EV-A71 infection in the Western Pacific region, and the propensity of EV-A71 strains to cause severe neurological complications have made this neurotropic virus a serious public health concern in afflicted countries. High mutation rate leading to viral quasispecies combined with frequent intra- and inter-typic recombination events amongst co-circulating EV-A71 strains have contributed to the great diversity and fast evolution of EV-A71 genomes, making impossible any accurate prediction of the next epidemic strain. Comparative genome sequence analyses and mutagenesis approaches have led to the identification of a number of viral determinants involved in EV-A71 fitness and virulence. These viral determinants include amino acid residues located in the structural proteins of the virus, affecting attachment to the host cell surface, receptor binding, and uncoating events. Critical residues in non-structural proteins have also been identified, including 2C, 3A, 3C proteases and the RNA-dependent RNA polymerase. Finally, mutations altering key secondary structures in the 5’ untranslated region were also found to influence EV-A71 fitness and virulence. While our current understanding of EV-A71 pathogenesis remains fragmented, these studies may help in the rational design of effective treatments and broadly protective vaccine candidates.

Epidemiological characteristics of hand, foot, and mouth disease in Yunnan Province, China, 2008-2019

BACKGROUND

Since 2016, enterovirus 71 (EV71) vaccines have been approved for market entry, and little is known about how the epidemiology of hand, foot, and mouth disease (HFMD) has been affected by the introduction of the vaccines in Yunnan Province. The study describes the epidemiological characteristics of HFMD before and after the introduction of EV71 vaccination in Yunnan Province.

METHODS

Surveillance data collected between 2008 and 2019 were analyzed to produce epidemiological distribution on cases, etiologic composition, and EV71 vaccination coverage, as well as to compare these characteristics before and after EV71 vaccination.

RESULTS

A total of 1,653,533 children received EV71 vaccines from 2016 through 2019 in Yunnan. The annual EV71 vaccination coverage rate ranged from 5.53 to 15.01% among children ≤5 years old. After the introduction of EV71 vaccines, the overall incidence of HFMD increased and reached over 200 cases per 100,000 population-years in 2018 and 2019. However, the case severity and case fatality rate decreased and remained lower than 1 and 0.005% after 2016, respectively. EV71-associated mild, severe and fatal cases sharply decreased. The predominant viral serotype changed to non-EV71/non-CV-A16 enteroviruses which were detected across the whole province.

CONCLUSIONS

Non-EV71/non-CV-A16 enteroviruses became the predominant strain and led to a higher incidence in Yunnan. Expanding EV71 vaccination and strengthening laboratory-based surveillance could further decrease the burden of severe HFMD and detect and monitor emerging enteroviruses.

Analysis of the coverage of inactivated enterovirus 71 (EV71) vaccine and adverse events following immunization with the EV71 vaccine among children from 2016 to 2019 in Guangzhou

Background: Since 2016, China has approved the use of inactivated enterovirus 71 (EV71) vaccines produced by three manufacturers. The coverage and safety of different EV71 vaccines need to be evaluated.Research design and methods: The EV71 vaccination and AEFI data were collected from the Guangzhou Children's Vaccination Information Report Management System and the China AEFI Monitoring Information Management System, and the EV71 vaccine coverage rate and the AEFI incidence rate were analyzed.Results: From 2016 to 2019, the number of people who should have been vaccinated in Guangzhou was 2,781,618, and the coverage rates for doses 1 and 2 were 24.71% and 19.44%, respectively. The inoculation rates of vaccines from manufacturers A and B were between 3.03 and 10.46%. The reported incidence of AEFIs was 11.97 per 100,000 (147 cases), with fever (106 cases, 8.63 per 100,000) and allergic rash (59 cases, 4.80 per 100,000) being the most common reactions. There were no differences in the AEFI responses to the EV71 vaccines from the three manufacturers.Conclusion: The EV71 vaccines from the three manufacturers have good safety, but the EV71 vaccine coverage rate is low. It is recommended that vaccine publicity be strengthened and that the vaccine coverage rate in children be increased.