Intradermal injection of a fractional dose of an inactivated HFMD vaccine elicits similar protective immunity to intramuscular inoculation of a full dose of an Al(OH)3-adjuvanted vaccine

Enterovirus 71 (EV71) and Coxsackievirus A16 (CVA16) are the two major causative agents of hand, foot and mouth disease (HFMD), which erupts in the Asia-Pacific regions. A bivalent vaccine against both EV71 and CVA16 is highly desirable. In the present study, on the bases that an experimental bivalent vaccine comprising of inactivated EV71 and CVA16 induces a balanced protective immunity against both EV71 and CVA16, we compare the immunogenicity and reactogenicity of one fourth of a full dose of an intradermal vaccine administered by needle-free liquid jet injector with a full dose of an intramuscular vaccine administered by needle-syringe in monkeys. The results suggest that intradermal injection of a fractional dose of an inactivated HFMD vaccine elicits similar immunogenicity and reactogenicity to intramuscular inoculation of a full dose of an Al(OH)₃-adjuvanted vaccine, regardless of whether monovalent or bivalent vaccines were used. Our results support the use of an intradermal bivalent vaccine strategy for HFMD vaccination in order to satisfy the requirements and reduce the costs.     

A novel inactivated enterovirus 71 vaccine can elicit cross-protective immunity against coxsackievirus A16 in mice

Hand, foot, and mouth disease (HFMD) is a highly contagious disease that mainly affects infants and children. Enterovirus 71 (EV71) and coxsackievirus A16 (CA16) are the major pathogens of HFMD. Two EV71 vaccines were recently licensed in China and the administration of the EV71 vaccines is believed to significantly reduce the number of HFMD-related severe or fatal cases. However, a monovalent EV71 vaccine cannot cross-protect against CA16 infection, this may result in that it cannot effectively control the overall HFMD epidemic. In this study, a chimeric EV71, whose VP1/210–225 epitope was replaced by that of CA16, was constructed using a reverse genetics technique to produce a candidate EV71/CA16 bivalent vaccine strain. The chimeric EV71 was infectious and showed similar growth characteristics as its parental strain. The replacement of the VP1/210–225 epitope did not significantly affect the antigenicity and immunogenicity of EV71. More importantly, the chimeric EV71 could induce protective immunity against both EV71 and CA16, and protect neonatal mice against either EV71 or CA16 lethal infections, the chimeric EV71 constructed in this study was shown to be a feasible and promising candidate bivalent vaccine against both EV71 and CA16. The construction of a chimeric enterovirus also provides an alternative platform for broad-spectrum HFMD vaccines development.     

A virus-like particle based bivalent vaccine confers dual protection against enterovirus 71 and coxsackievirus A16 infections in mice

Enterovirus 71(EV71) and coxsackievirus A16 (CA16) are responsible for hand, foot and mouth disease which has been prevalent in Asia-Pacific regions, causing significant morbidity and mortality in young children. Co-circulation of and co-infection by both viruses underscores the importance and urgency of developing vaccines against both viruses simultaneously. Here we report the immunogenicity and protective efficacy of a bivalent combination vaccine comprised of EV71 and CA16 virus-like particles (VLPs). We show that monovalent EV71- or CA16-VLPs-elicited serum antibodies exhibited potent neutralization effect on the homotypic virus but little or no effect on the heterotypic one, whereas the antisera against the bivalent vaccine formulation were able to efficiently neutralize both EV71 and CA16, indicating there is no immunological interference between the two antigens with respect to their ability to induce virus-specific neutralizing antibodies. Passive immunization with monovalent VLP vaccines protected mice against a homotypic virus challenge but not heterotypic infection. Surprisingly, antibody-dependent enhancement (ADE) of disease was observed in mice passively transferred with mono-specific anti-CA16 VLP sera and subsequently challenged with EV71. In contrast, the bivalent VLP vaccine conferred full protection against lethal challenge by either EV71 or CA16, thus eliminating the potential of ADE. Taken together, our results demonstrate for the first time that the bivalent VLP approach represents a safe and efficacious vaccine strategy for both EV71 and CA16.     

Efficacy of an inactivated bivalent vaccine for enterovirus 71 and coxsackievirus A16 in mice immunized intradermally

Human hand, foot, and mouth disease (HFMD), an important infectious disease in children, is caused mainly by enterovirus 71 (EV71) and coxsackievirus A16 (CA16). In this study, a bivalent inactivated EV71/CA16 vaccine is developed and evaluated in immunized BALB/c mice injected through the intradermal route. Q-RT-PCR detection of the mRNA of immune signal molecules in local epithelial tissues inoculated with the vaccine indicates activation of innate immunity, which includes upregulation of immune-related chemokines, interferons and CD molecules. Further, the finding that neutralizing antibodies and specific T cellular responses were elicited in adult mice after two immunizations with the vaccine at a 28-day interval, which endowed offspring mice to defend a viral challenge, suggests the successful induction of specific protective antiviral immunity. All these data suggest that immunization with this bivalent EV71/CA16 vaccine via the intradermal route elicits effective immunity against EV71 and CA16 infection.     

Hexon-modified recombinant E1-deleted adenoviral vectors as bivalent vaccine carriers for Coxsackievirus A16 and Enterovirus 71

Hand, foot and mouth disease (HFMD) is a major public health concern in Asia; more efficient vaccines against HFMD are urgently required. Adenoviral (Ad) capsids have been used widely for the presentation of foreign antigens to induce specific immune responses in the host. Here, we describe a novel bivalent vaccine for HFMD based on the hexon-modified, E1-deleted chimpanzee adenovirus serotype 68 (AdC68). The novel vaccine candidate was generated by incorporating the neutralising epitope of Coxsackievirus A16 (CA16), PEP71, into hypervariable region 1 (HVR1), and a shortened neutralising epitope of Enterovirus 71 (EV71), sSP70, into HVR2 of the AdC68 hexon. In order to enhance the immunogenicity of EV71, VP1 of EV71 was cloned into the E1-region of the AdC68 vectors. The results demonstrated that these two epitopes were well presented on the virion surface and had high affinity towards specific antibodies, and VP1 of EV71 was also significantly expressed. In pre-clinical mouse models, the hexon-modified AdC68 elicited neutralising antibodies against both CA16 and EV71, which conferred protection to suckling mice against a lethal challenge of CA16 and EV71. In summary, this study demonstrates that the hexon-modified AdC68 may represent a promising bivalent vaccine carrier against EV71 and CA16 and an epitope-display platform for other pathogens.     

Hepatitis B virus core particles containing multiple epitopes confer protection against enterovirus 71 and coxsackievirus A16 infection in mice

Human enterovirus 71 (EV71) and coxsackievirus A16 (CA16) are the two major causative agents of hand-foot-and-mouth disease (HFMD). To investigate novel combined vaccines to prevent EV71 and CA16 infection, we constructed chimeric virus-like particles (tHBc/SPA or tHBc/SP VLPs) displaying conserved epitopes of EV71 (aa 208–222 of VP1 and aa 248–263 of VP2) and CA16 (aa271-285 of VP1) using a truncated hepatitis B virus core carrier (tHBc). Immunization with the chimeric VLPs induced epitope- or virus-specific IgG and neutralization antibodies against EV71 and CA16 in the mice. Compared with inactivated EV71, the chimeric VLPs induced significantly increased Th1 cytokine (IFN-γ, IL-2) production and decreased Th2 cytokine (IL-4, IL-10) responses. Neonatal mice born to dams immunized with the recombinant particles were completely protected from lethal EV71 and partially protected from CA16 infection. Co-expression of the conserved human MHC class I CD4+ T cell epitope (aa248-263 of VP2) did not improve the antiviral immunity of the chimeric VLP vaccine in mice. Our results demonstrate that experimental combination vaccines comprised of EV71 and CA16 epitopes induce both humoral and cellular immune responses and therefore support further preclinical and clinical development of a bivalent VLP vaccine targeting both CA16 and EV71.     

Formaldehyde-inactivated human enterovirus 71 vaccine is compatible for co-immunization with a commercial pentavalent vaccine

In this study we tested the effectiveness of a formaldehyde-inactivated EV71 vaccine and its compatibility for co-immunization with a pentavalent vaccine that contained inactivated poliovirus (PV) vaccine. The inactivated EV71 vaccine (C2 genogroup) elicited an antibody response which broadly neutralized homologous and heterologous genogroups, including B4, C4, and B5. Pups from vaccinated dams were resistant to the EV71 challenge and had a high survival rate and a low tissue viral burden when compared to those from non-vaccinated counterparts. Co-immunization with pentavalent and inactivated EV71 vaccines elicited antibodies against the major components of the pentavalent vaccine including the PV, Bordetella pertussis, Haemophilus influenzae type b, diphtheria toxoid, and tetanus toxoid at the same levels as in mice immunized with pentavalent vaccine alone. Likewise, EV71 neutralizing antibody titers were comparable between EV71-vaccinated mice and mice co-immunized with the two vaccines. These results indicate that formaldehyde-inactivated whole virus EV71 vaccine is feasible for designing multivalent vaccines.     

The immunogenicity and protection effect of an inactivated coxsackievirus A6, A10, and A16 vaccine against hand,foot, and mouth disease

Coxsackievirus belongs to the Enterovirus genus of the Picornaviridae family and is one of the major pathogens associated with human hand, foot, and mouth disease (HFMD). Historically, outbreaks of HFMD have mainly been caused by enterovirus 71 and coxsackievirus A16. Recently, coxsackieviruses A6 and A10 have been associated with increased occurrences of sporadic HFMD cases and outbreak events globally. In this study, the immunogenicity of coxsackieviruses A6, A10, and A16 (CA6, CA10, and CA16), which were inactivated by formalin or β-propiolactone (BPL) under different conditions, was evaluated as multivalent vaccine candidates. CA6 induced similar immune responses with both inactivation methods, and the immune efficacy of CA10 and CA16 was better following inactivation with BPL than with formalin. There was no sufficient cross-reactivity or cross-protectivity against heterologous strains in groups vaccinated with the BPL-inactivated (BI) monovalent vaccine. Sufficient neutralizing antibody and cell-mediated immune responses were induced in the BI-trivalent vaccinated group. These findings suggest that BI-CA6, CA10, and CA16 are potential multivalent vaccine candidates and that a multivalent vaccine is needed to control HFMD. The coxsackievirus multivalent vaccine could be useful for the development of effective HFMD vaccines.     

Preclinical evaluation of recombinant HFMD vaccine based on enterovirus 71 (EV71) virus-like particles (VLP): Immunogenicity,efficacy and toxicology

Enterovirus 71 (EV71) is one of the major causative agents for hand, foot and mouth disease (HFMD) in children. Currently, three inactivated EV71 vaccines have been approved by Chinese government. We previously demonstrated that recombinant EV71 virus-like particles (VLP) produced in Pichia pastoris can be produced at a high yield with a simple manufacturing process, and the candidate vaccine elicited protective humoral immune responses in mice. In present study, the nonclinical immunogenicity, efficacy and toxicity of the EV71 vaccine was comprehensively evaluated in rodents and non-human primates. The immunogenicity assessment showed that EV71 VLPs vaccine elicited high and persistent neutralizing antibody responses, which could be comparable with a licensed inactivated vaccine in animals. The immune sera of vaccinated mice also exhibited cross-neutralization activities to the heterologous subtypes of EV71. Both passive and maternal antigen specific antibodies protected the neonatal mice against the lethal EV71 challenge. Furthermore, nonclinical safety assessment of EV71 VLP vaccine showed no signs of systemic toxicity in animals. Therefore, the excellent immunogenicity, efficacy and toxicology data supported further evaluation of the VLP-based EV71 vaccine in humans.     

Study of integrated protective immunity induced in rhesus macaques by the intradermal administration of a bivalent EV71-CA16 inactivated vaccine

Enterovirus type 71 (EV71) and coxsackievirus A 16 (CA16) are recognized as the major pathogens responsible for human hand-foot-mouth disease. To develop a bivalent EV71-CA16 vaccine, rhesus macaques immunized with two doses of this vaccine via the intradermal route were challenged with EV71 or CA16, and their clinical symptoms, viral shedding, neutralizing antibodies, IFN-γ-specific ELISpots, and tissue viral load were examined longitudinally. Specific immunity against EV71 and CA16 was observed in the macaques, which exhibited controlled proliferation of the EV71 and CA16 viruses and upregulated expression of immune-related genes compared with the controls. Furthermore, broad protection against EV71 and CA16 challenge without immunopathological effects was observed in all the immunized macaques. These studies suggest that the bivalent EV71-CA16 inactivated vaccine was effective against wild-type EV71 or CA16 viral challenge in rhesus macaques.     

High-yield production of recombinant virus-like particles of enterovirus 71 in Pichia pastoris and their protective efficacy against oral viral challenge in mice

Enterovirus 71 (EV71) is one of the major causative pathogens of hand, foot and mouth disease (HFMD), which is highly prevalent in the Asia-Pacific regions. Severe HFMD cases with neurological complications and even death are often associated with EV71 infections. However, no licensed EV71 vaccine is currently available. Recombinant virus-like particles (VLPs) of EV71 have been produced and shown to be a promising vaccine candidate in preclinical studies. However, the performance of current recombinant expression systems for EV71 VLP production remains unsatisfactory with regard to VLP yield and manufacturing procedure, and thus hinders further product development. In this study, we evaluated the expression of EV71 VLPs in Pichia pastoris and determined their protective efficacy in mouse models of EV71 infections. We showed that EV71 VLPs could be produced at high levels up to 4.9% of total soluble protein in transgenic P. pastoris yeast co-expressing P1 and 3CD proteins of EV71. The resulting yeast-produced VLPs potently induced neutralizing antibodies against homologous and heterologous EV71 strains in mice. More importantly, maternal immunization with VLPs protected neonatal mice in both intraperitoneal and oral challenge experiments. Collectively, these results demonstrated the success of simple, high-yield production of EV71 VLPs in transgenic P. pastoris, thus lifting the major roadblock in commercial development of VLP-based EV71 vaccines.     

Chimeric enterovirus 71 virus-like particle displaying conserved coxsackievirus A16 epitopes elicits potent immune responses and protects mice against lethal EV71 and CA16 infection

Hand-foot-and-mouth disease (HFMD) is an infectious disease of infants and young children frequently caused by the enterovirus A species, mainly enterovirus 71 (EV71) and coxsackievirus A16 (CA16). In this study, we prepared the EV71 virus-like particle (EV71-VLP) and its chimeras using recombinant baculovirus (Bac-P1-3CD) co-expressing EV71 P1 (under polyhedrin promoter) and 3CD (under CMV-IE promoter) proteins in Sf9 cells. EV71-VLP chimera ChiEV71(1E)-VLP or ChiEV71(4E)-VLP displayed single CA16 PEP71 epitope in VP1 or four conserved CA16 neutralizing epitopes (PEP71 in VP1, aa136-150 in VP2, aa176-190 in VP3 and aa48-62 in VP4) by substitution of the corresponding regions of EV71 structure proteins, respectively. In mice, EV71-VLP and its chimeras elicited similar EV71-specific IgG and neutralizing antibody (NAb) titers compared to inactivated EV71. Expectedly, vaccination of ChiEV71(1E)-VLP or ChiEV71(4E)-VLP resulted in significantly increased CA16-specific IgG and NAb production and improved cross-protection against CA16 infection compared to EV71-VLP. Interestingly, the VLPs induced potent cellular immune responses and significantly decreased Th2 type (IL-4 and IL-10) cytokines secretion in the splenocytes of immunized mice compared to inactivated EV71 or inactivated CA16. Neonatal mice born to dams immunized with the chimeric VLPs or neonatal mice passively transferred with sera of immunized mice were completely protected from lethal EV71 challenge and partially protected from lethal CA16 infection. Our study provides a novel bivalent or multivalent vaccine strategy to prevent EV71 and related-enterovirus infections.     

Active immunization with a Coxsackievirus A16 experimental inactivated vaccine induces neutralizing antibodies and protects mice against lethal infection

Coxsackievirus A16 (CA16) is one of the main pathogens that cause hand, foot and mouth disease, which frequently occurs in young children. A small percentage of patients infected with CA16 may suffer from severe neurological complications that could also lead to death. Recent epidemiological data shows the increase in both the total number and the incidence rate of severe CA16-associated cases in China, indicating that CA16 should be targeted for vaccine development. In this article, we report the immunogenicity and protective efficacy of experimental inactivated CA16 vaccines in mice. We show that immunization with β-propiolactone-inactivated whole-virus vaccines derived from two CA16 clinical isolates were able to induce CA16-specific antibody and IFN-secreting T-cell responses in mice. The resulting anti-CA16 mouse sera neutralized both homologous and heterologous CA16 clinical isolates, as well as a mouse-adapted strain called CA16-MAV, which is capable of infecting 14-day-old mice. Passive transfer of anti-CA16 neutralizing sera partially protected neonatal mice from lethal challenge by a clinical isolate CA16-G08. More significantly, active immunization of mice with the inactivated vaccines conferred complete protection against lethal infection with CA16-MAV. Collectively, these results provide a solid foundation for further development of inactivated whole-virus CA16 vaccines for human use.     

Prospect and challenges for the development of multivalent vaccines against hand,foot and mouth diseases

Enterovirus 71 (EV71), an emerging neurotropic virus and coxsackieviruses (CV) are the major causative agents of hand, foot and mouth diseases (HFMD). These viruses have become a serious public health threat in the Asia Pacific region. Formalin-inactivated EV71 (FI-EV71) vaccines have been developed, evaluated in human clinical trials and were found to elicit full protection against EV71. Their failure to prevent CVA16 infections could compromise the acceptability of monovalent EV71 vaccines. Bivalent FI-EV71/FI-CVA16 vaccines have been found to elicit strong neutralizing antibody responses against both viruses in animal models but did not protect against CVA6 and CVA10 viral infections in cell culture neutralization assay. In this review, we discuss the critical bottlenecks in the development of multivalent HFMD vaccines, including the selection of vaccine strains, animal models to assess vaccine potency, the definition of end-points for efficacy trials, and the need for improved manufacturing processes to produce affordable vaccines.     

A bivalent virus-like particle based vaccine induces a balanced antibody response against both enterovirus 71 and norovirus in mice

Noroviruses are the main cause of severe viral gastroenteritis, which results in estimated 200,000 deaths each year, primarily in children in the developing world. Genogroup II.4 (GII.4) strains are responsible for the majority of norovirus outbreaks. Enterovirus 71 (EV71), the leading causative agent of hand, foot and mouth disease, has recently been prevalent in Asia-Pacific regions, resulting in significant morbidity and mortality in young children. However, no vaccine is commercially available for either norovirus GII.4 or EV71. Recombinant virus-like particles (VLPs) derived from either GII.4 or EV71 have been shown to be promising monovalent vaccine candidates. In this study, we investigate the possibility to formulate a VLP-based bivalent vaccine for both norovirus GII.4 and EV71. The GII.4- and EV71-VLPs were produced in a baculovirus-insect cell expression system. A bivalent combination vaccine comprised of GII.4 and EV71 VLPs was formulated and compared with monovalent GII.4- and EV71-VLPs for their immunogenicity in mice. We found that the bivalent vaccine elicited durable antibody responses toward both GII.4 and EV71, and the antibody titers were comparable to that induced by the monovalent vaccines, indicating there is no immunological interference between the two antigens in the combination vaccine. More significantly, the bivalent vaccine-immunized mouse sera could efficiently neutralize EV71 infection and block GII.4-VLP binding to mucin. Together, our results demonstrate that the experimental combination vaccine comprised of GII.4 and EV71-VLPs is able to induce a balanced protective antibody response, and therefore strongly support further preclinical and clinical development of such a bivalent VLP vaccine targeting both norovirus GII.4 and EV71.     

Inactivated coxsackievirus A10 experimental vaccines protect mice against lethal viral challenge

Coxsackievirus A10 (CVA10) has become one of the major causative agents of hand, foot and mouth disease (HFMD). It is now recognized that CVA10 should be targeted for vaccine development. We report here that β-propiolactone inactivated whole-virus based CVA10 vaccines can elicit protective immunity in mice. We prepared two inactivated CVA10 experimental vaccines derived from the prototype strain CVA10/Kowalik and from a clinical isolate CVA10/S0148b, respectively. Immunization with the experimental vaccines elicited CVA10-specific serum antibodies in mice. The antisera from vaccinated mice could potently neutralize in vitro infection with either homologous or heterologous CVA10 strains. Importantly, passive transfer of the anti-CVA10 sera protected recipient mice against CVA10/Kowalik or CVA10/S0148b infections. Moreover, active immunization with the inactivated vaccines also conferred protection against homologous and heterologous infections in mice. Collectively, our results demonstrate the proof-of-concept for inactivated whole-virus based CVA10 vaccines.     

Coxsackievirus A 16 infection does not interfere with the specific immune response induced by an enterovirus 71 inactivated vaccine in rhesus monkeys

Hand, foot and mouth disease is usually caused by enterovirus 71 (EV71) and coxsackievirus A 16 (CA16), which are members of the Picornaviridae family. In the present study, the characteristics of the immune response induced by an EV71 inactivated vaccine (made from human diploid cells) were explored in the presence of CA16 infection, based on the previously established neonatal rhesus monkey model. The typical clinical manifestations, including body temperature, viral viremia and virus shedding in the mouth, pharynx and feces, were characterized. A specific neutralizing antibody assay showed that the specific immune response induced by the EV71 inactivated vaccine was active against EV71 but not against CA16. No remarkable fluctuation in proinflammatory cytokine release was identified in the serum of immunized monkeys with EV71 vaccine and CA16 infections subsequently. The results showed that the specific immune response induced by the EV71 inactivated vaccine is effective against EV71 infection but is not affected by CA16 infection.     

Identification of conserved neutralizing linear epitopes within the VP1 protein of coxsackievirus A16

Coxsackievirus A16 (CA16) is a major causative agent of hand, foot, and mouth disease. Immunization with inactivated whole-virus or recombinant virus-like particles (VLP) of CA16 elicits neutralizing antibodies that protect mice against lethal challenge. However, the epitope/s responsible for this induction has not been determined. In this investigation, we identified six neutralizing linear epitopes of CA16. A panel of 95 synthetic peptides spanning the entire VP1 protein of CA16 were screened by ELISA for reactivity with neutralizing antisera against CA16 VLPs, which were generated in a previous study (Vaccine 30:6642–6648). Fifteen high-binding peptides were selected and further examined for their inhibitory effect on neutralization by anti-VLP sera. Among them, six peptides with no overlap significantly inhibited neutralization. Mice immunized with these six peptides generated peptide-specific serum antibodies. The anti-peptide antisera positively detected CA16 via immunofluorescent staining and Western blot assays. More importantly, they neutralized both homologous and heterologous CA16 strains, indicating that these six peptides represented neutralizing epitopes. Sequence alignment also showed that these epitopes are extremely conserved among CA16 strains of different genotypes. These findings have important implications for the development of peptide-based broadly protective CA16 vaccines.     

Cross-reactive neutralizing antibody epitopes against Enterovirus 71 identified by an in silico approach

Currently, infections of hand, foot and mouth disease (HFMD) due to Human Enterovirus 71 (EV71) cannot be prevented or treated, as there are no suitable vaccines or antiviral drugs. This study aimed to identify potential vaccine candidates for EV71 using in silico analysis of its viral capsid proteins. A combined in silico approach utilizing computational hidden Markov model (HMM), propensity scale algorithm, and artificial learning, identified three 15-mer structurally conserved B-cell epitope candidates lying within the EV71 capsid proteins. Peptide vaccine candidates incorporating a target B-cell epitope and a promiscuous T-cell epitope from the related polio virus were synthesized using solid-phase Fmoc chemistry. Inbred BALB/C mice which were inoculated with two 10 μg doses of the synthetic peptide, generated anti-peptide antibodies. Purified IgG isolated from pooled sera of the inoculated mice neutralized EV71 infections in vitro. Furthermore, these neutralizing antibodies were cross-reactive against other members of the Picornaviridae family, demonstrating greater than 50% virus neutralization. This indicates that the current approach is promising for the development of synthetic peptide-based vaccine candidates against Picornaviridae. Development of effective vaccines is of paramount importance in managing the disease in the Asia Pacific regions where this virus is endemic and has significant social, economic and public health ramifications.     

2017-2021年中国肠道病毒71型灭活疫苗接种现状分析

目的了解2017-2021年中国肠道病毒71型(EV71)灭活疫苗接种现状, 为制定手足口病防控和免疫策略提供参考。方法利用中国免疫规划信息管理系统收集的EV71灭活疫苗报告接种剂次数和出生人口数据估算2012年以来各出生队列截至2021年底的全国、分省和分地市EV71灭活疫苗累计接种率, 并分析与接种率水平相关的潜在影响因素。结果截至2021年, 全国2012年以来出生队列EV71灭活疫苗估算累计接种率为24.96%, 各省份估算接种率为3.09%～56.59%, 各地市估算接种率为0～88.17%。不同地区疫苗接种率与该地区既往手足口病报告发病水平和人均可支配收入的相关性均有统计学意义。结论 2017年以来EV71灭活疫苗在全国范围内应用广泛, 但地区间疫苗接种覆盖情况差异较大, 经济相对发达地区接种率较高, 既往疾病流行强度可能对疫苗的接受度和接种服务模式产生一定影响。EV71灭活疫苗接种对手足口病流行的影响还需进一步研究。