Analysis of HFMD Transmissibility Among the Whole Population and Age Groups in a Large City of China

Abstract

BackgroundHand-Foot-and-Mouth-Disease (HFMD) has been widely spread in Asia, and has result in a high disease burden for children in many countries. However, the dissemination characteristics intergroup and between different age groups are still not clear. In this study, we aim to analyze the differences in the transmissibility of HFMD, in the whole population and among age groups in Shenzhen city, by utilizing mathematical models.MethodsA database that reports HFMD cases in Shenzhen city from January 2010 to December 2017 was collected. In the first stage, a Susceptive-Infected-Recovered (SIR) model was built to fit data of Shenzhen city and its districts, and Reff was used to assess transmissibility in each district. In the second stage, a cross-age groups SIR model was constructed to calculate the difference in transmissibility of reported cases among three age groups of EV71 virus: 0–3 years, 3–5 years, and over 5 years which was denoted as age group 1, 2, and 3, respectively.ResultsFrom 2010 to 2017, 345,807 cases of HFMD were reported in Shenzhen city, with peak incidence in spring and autumn in Shenzhen city and most of its districts each year. Analysis of the EV71 incidence data by age group revealed that age Group 1 have the highest incidence (3.13 ×10−7–2.31 ×10−4) while age group 3 had the lowest incidence (0–3.54 ×10−5). The differences in weekly incidence of EV71 between age groups were statistically significant (t12 = 7.563, P < 0.0001; t23 = 12.420, P < 0.0001; t13 = 16.996, P < 0.0001). The R2 of the SIR model Shenzhen city population-wide HFMD fit for each region was >0.5, and P < 0.001. Reff values were >1 for the vast majority of time and regions, indicating that the HFMD virus has the ability to spread in Shenzhen city over the long-term. Differences in Reff values between regions were judged by using analysis of variance (ANOVA) (F = 0.541, P = 0.744). SiIiRi-SjIjRj models between age groups had R2 over 0.7 for all age groups and P <0.001. The Reff values between groups show that the 0–2 years old group had the strongest transmissibility (median: 2.881, range: 0.017–9.897), followed by the over 5 years old group (median: 1.758, range: 1.005–5.279), while the 3–5 years old group (median: 1.300, range: 0.005–1.005) had the weakest transmissibility of the three groups. Intra-group transmissibility was strongest in the 0–2 years age group (median: 1.787, range: 0–9.146), followed by Group 1 to Group 2 (median: 0.287, range: 0–1.988) and finally Group 1 to Group 3 (median: 0.287, range: 0–1.988).ConclusionThe incidence rate of HFMD is high in Shenzhen city. In the data on the incidence of EV71 in each age group, the highest incidence was in the 0–2 years age group, and the lowest incidence was in the over 5 years age group. The differences in weekly incidence rate of EV71 among age groups were statistically significant. Children with the age of 0–2 years had the highest transmissibility.

Assessing the modification impact of vaccination on the relationship of the Discomfort Index with hand, foot, and mouth disease in Guizhou: A multicounty study

“…This can effectively reduce the transmission routes of HFMD and mitigate the risk of infection. In addition, the differences in HFMD risk between the two economic zones observed in the stratified analyses mainly stemmed from socioeconomic factors such as GDP per capita and population density [ 37 , 38 ]. This study suggests that the necessity for future research to thoroughly consider factors such as race, sex, and economic level when assessing the intervention effects of vaccine policies.…”

“…Second, there are some limitations in terms of delving deeper into and validating the underlying pathological mechanisms because the study data were derived from monitoring data. Third, as in other recent studies [ 37 , 38 ], we chose to exclude data during the COVID-19 pandemic period to ensure the reliability of our findings, considering that the pandemic may lead to changes in healthcare resources, public health policies, and public behavior which could affect the incidence of HFMD [ 39 , 40 ]. In addition, despite our efforts to consider a variety of factors, the presence of unknown confounding variables may affect our interpretation of the effects of vaccine policies.…”

Recent Progress in Innate Immune Responses to Enterovirus A71 and Viral Evasion Strategies

“…Accordingly, the mucosal immune system of these sites plays a crucial role in host defense against enteroviruses. Notably, while HFMD cases are more frequent in older children, the highest susceptible rates occur in children under 5 years old that are known for their immature immune system and for clustering at the preschool level [ 40 , 41 ]. Likewise, many enterovirus infections go unnoticed and are cleared before the production of antibodies [ 42 ], indicating that the host innate immunity comprises the primary protection from enteroviruses (summarized in Figure 2 ).…”