This multicenter, randomized, double-blind, controlled Phase III clinical trial aims to evaluate the efficacy, safety, and immunogenicity of the bivalent enterovirus-inactivated vaccine (Vero cell) in healthy children aged 6 to 71 months. The main questions it aims to answer are: * The primary vaccine efficacy of the investigational vaccine against Hand, Foot, and Mouth Disease（HFMD) caused by CA16 infection compared to the control vaccine. * The neutralizing antibody levels against EV71 in the trial group are non-inferior to those in the control group after two doses of vaccination. Researchers will compare the bivalent enterovirus-inactivated vaccine (Vero cell) to the EV71-inactivated vaccine (Vero cell) to prevent HFMD and Herpangina(HA). Participants will be randomly assigned to the trial group and the control group in a 1:1 ratio to receive two doses of the investigational vaccine or the control EV71 vaccine, with a one-month interval between doses.
This trial employs a multicenter, randomized, double-blind, controlled design. With informed consent, 8000 healthy children participants aged 6 to 71 months will be enrolled, with 4000 participants aged 6 to 23 months and 4000 participants aged 24 to 71 months, maintaining a balanced gender ratio. Among them, 4000 participants aged 6 to 23 months and 3600 participants aged 24 to 71 months have no history of EV71 vaccination, while 400 participants aged 24 to 71 months have a history of EV71 vaccination. All participants will be randomly assigned to the trial and control groups at a 1:1 ratio, receiving two doses of the experimental vaccine or the control EV71 vaccine, with a one-month interval between doses. Each participant enters the case monitoring period after the first dose, which lasts until the end of two consecutive epidemic seasons. The effective monitoring period begins 14 days after the second dose, with the period before being the monitoring window period. During the case monitoring period, if a participant meets the criteria for a suspected case of enterovirus infection through active follow-up by the researcher or self-reporting by the participant's guardian, a throat swab and/or rectal swab will be collected for RT-PCR nucleic acid testing within three days of the first appearance of symptoms, followed by subsequent follow-up/sampling based on the test results. The protective efficacy of the investigational vaccine will be analyzed based on cases caused by laboratory-confirmed CA16 infections. In addition, enterovirus infection cases collected in this study will be subjected to viral isolation and sequencing analysis to understand their genetic subtypes. Researchers collect all adverse events (AEs) within 30 minutes after each dose for all participants and serious adverse events (SAEs) from the first vaccination dose to six months after the second dose. Furthermore, any AEs reported by the participant's guardian or known through any other means from the first dose to 30 days after the second dose will be paid attention to, recorded truthfully, and included in the analysis. A subgroup of 2000 participants will be selected for reactogenicity, including 1000 participants aged 6 to 23 months with no history of EV71 vaccination, 800 participants aged 24 to 71 months with no history of EV71 vaccination, and 200 participants aged 24 to 71 months with a history of EV71 vaccination. For the reactogenicity subgroup, diary cards will be used to collect solicited and unsolicited AEs within 0 to 7 days after each dose, and contact cards will be used to collect AEs from 8 to 30 days after each dose. A subgroup of 1200 participants from the reactogenicity subgroup will be selected for immunogenicity evaluation, including humoral and cellular immunogenicity subgroups. The humoral immunogenicity subgroup includes 1160 participants aged 6 to 71 months, with 580 participants aged 6 to 23 months with no history of EV71 vaccination, 380 participants aged 24 to 71 months with no history of EV71 vaccination, and 200 participants aged 24 to 71 months with a history of EV71 vaccination. Venous blood of approximately 3.0ml will be collected from the humoral immunogenicity subgroup before the first dose and at 30 days, 6 months, and 12 months after the second dose. Serum collected from all participants in the humoral immunogenicity subgroup at the above four time points will be used for neutralizing antibody testing against EV71 and CA16, to evaluate the immunogenicity and duration of immunity against EV71 and CA16. Additionally, the first 100 participants with a history of EV71 vaccination and the first 100 participants without a history of EV71 vaccination from the humoral immunogenicity subgroup will be selected for neutralizing antibody testing against CA10 and CA6 using their serum before the first dose and at 30 days after the second dose; the serum of the remaining 960 participants in the humoral immunogenicity subgroup will be used for neutralizing antibody testing against different serotypes of enteroviruses, including EV71 and CA16, before the first dose and at 30 days after the second dose. From the humoral immunogenicity subgroup, 50 participants aged less than 12 months with no history of EV71 vaccination will be selected to complete the full vaccination through intramuscular injection on the anterolateral thigh, while the rest of the participants complete the full vaccination through intramuscular injection on the deltoid muscle of the upper arm, for analysis of immunogenicity at different injection sites. The cellular immunogenicity subgroup will include 40 participants aged 24 to 71 months with no history of EV71 vaccination. Venous blood of approximately 3.0ml will be collected before each dose and on the 14th day after each dose for the detection and analysis of mononuclear cell INF-γ and IL-4 expression.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
8,000
Two doses are administered with a one-month interval between each dose.
Two doses are administered with a one-month interval between each dose.
Anhui Provincial Center for Disease Control and Prevention
Hefei, Anhui, China
RECRUITINGFujian Provincial Center for Disease Control and Prevention
Fujian, China
RECRUITINGGuangdong Provincial Center for Disease Control and Prevention
Guangdong, China
RECRUITINGHubei Provincial Center for Disease Control and Prevention
Hubei, China
RECRUITINGEvaluate the primary vaccine efficacy of the trial vaccine against HFMD caused by CA16 infection compared to the control vaccine.
Evaluate the primary vaccine efficacy of the trial vaccine against HFMD caused by CA16 infection, diagnosed by RT-PCR, in children aged 6 to 71 months (with and without a history of EV71 vaccination) 14 days after full vaccination (based on data from at least 47 cases). The vaccine's efficacy will be evaluated by monitoring the annual incidence rate of HFMD attributable to CA16 infection, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) nucleic acid testing, following complete full immunization for 14 days based on data from at least 47 cases until the end of one epidemic seasons.
Time frame: 1 year
Evaluate whether the neutralizing antibody levels against EV71 in the trial group are non-inferior to those in the control group after two doses of vaccination.
Evaluate the seroconversion rate and geometric mean titer (GMT) of EV71 neutralizing antibodies in participants aged 6-71 months without a history of EV71 vaccination and negative for EV71 antibodies before immunization, 30 days after full vaccination.
Time frame: 60 days
Evaluate the safety of the trial vaccine.
1. Monitor the incidence of adverse events (AEs) within 0-30 days after each dose of the trial vaccine. 2. Monitor the incidence of adverse reacts (ARs) within 0-30 days after each dose of the trial vaccine. 3. Monitor the incidence of serious adverse events (SAEs) from the start of vaccination until 6 months after the full vaccination.
Time frame: 6 monthes
Evaluate the long-term vaccine efficacy of the trial vaccine compared to the control vaccine against HFMD caused by CA16 infection
Evaluate the vaccine efficacy against CA16 infection-induced HFMD, confirmed by RT-PCR, in the entire population (including those with and without a history of EV71 vaccination) from 14 days after full immunization until the end of two consecutive epidemic seasons. The vaccine's efficacy will be evaluated by monitoring the annual incidence rate of HFMD attributable to CA16 infection, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) nucleic acid testing, following complete full immunization for 14 days until the end of two epidemic seasons.
Time frame: 2 years
Evaluate the long-term vaccine efficacy of the trial vaccine compared to the control vaccine against Herpangina(HA) caused by CA16 infection
Evaluate the vaccine efficacy against HA caused by CA16 infection, confirmed by RT-PCR, in the entire population (including those with and without a history of EV71 vaccination) from 14 days after full immunization until the end of two consecutive epidemic seasons. The vaccine's efficacy will be evaluated by monitoring the annual incidence rate of HA attributable to CA16 infection, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) nucleic acid testing, following complete full immunization for 14 days until the end of two epidemic seasons.
Time frame: 2 years
Evaluate the seroconversion rate of the neutralizing antibodies against CA16 and EV71 in populations without a history of EV71 vaccination.
On the 30th day after full vaccination, assess the seroconversion rate of neutralizing antibodies against CA16 and EV71 in populations without a history of EV71 vaccination.
Time frame: 60 days
Evaluate the seropositivity rate of neutralizing antibodies against CA16 and EV71 in populations without a history of EV71 vaccination.
On the 30th day after full vaccination, assess the seropositivity rate of neutralizing antibodies against CA16 and EV71 in populations without a history of EV71 vaccination.
Time frame: 60 days
Evaluate the GMT of the neutralizing antibodies against CA16 and EV71 in populations without a history of EV71 vaccination.
On the 30th day after full vaccination, assess the GMT of neutralizing antibodies against CA16 and EV71 in populations without a history of EV71 vaccination.
Time frame: 60 days
Evaluate the geometric mean increase (GMI) of neutralizing antibodies against CA16 and EV71 in populations without a history of EV71 vaccination.
On the 30th day after full vaccination, assess the GMI of neutralizing antibodies against CA16 and EV71 in populations without a history of EV71 vaccination.
Time frame: 60 days
Evaluate the vaccine efficacy of the trial vaccine compared to the control vaccine against diseases caused by CA16 infection.
Evaluate the vaccine efficacy against CA16 infection-related diseases (such as HFMD, HA, gastrointestinal diseases, etc.), confirmed by RT-PCR, in the entire population (including those with and without a history of EV71 vaccination) 14 days after full immunization. The vaccine's efficacy will be evaluated by monitoring the annual incidence rate of diseases (such as HFMD, HA, gastrointestinal diseases, etc.) attributable to CA16 infection, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) nucleic acid testing, following complete full immunization for 14 days until the end of two epidemic seasons.
Time frame: 2 years
Evaluate the vaccine efficacy of the trial vaccine compared to the control vaccine against severe cases caused by CA16 infection.
Evaluate the vaccine efficacy against severe cases caused by CA16 infection, confirmed by RT-PCR, in the entire population (including those with and without a history of EV71 vaccination) 14 days after full immunization. The vaccine's efficacy will be evaluated by monitoring the annual incidence rate of severe cases attributable to CA16 infection, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) nucleic acid testing, following complete full immunization for 14 days until the end of two epidemic seasons.
Time frame: 2 years
Evaluate the vaccine efficacy of the trial vaccine compared to the control vaccine against hospitalization cases caused by CA16 infection.
Evaluate the vaccine efficacy against hospitalization cases caused by CA16 infection, confirmed by RT-PCR, in the entire population (including those with and without a history of EV71 vaccination) 14 days after full immunization. The vaccine's efficacy will be evaluated by monitoring the annual incidence rate of hospitalization cases attributable to CA16 infection, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) nucleic acid testing, following complete full immunization for 14 days until the end of two epidemic seasons.
Time frame: 2 years
Evaluate the level of cellular immunity induced by the trial vaccine.
Measure the number of IFN-γ and IL-4 spot-forming cells per 3×10\^6 peripheral blood mononuclear cells (PBMCs) from participants aged 24 to 71 months without a history of EV71 vaccination, before each immunization and on the 14th day after each vaccination.
Time frame: 44 days
Evaluate the immunological persistence of the trial vaccine via the seropositivity rate of neutralizing antibodies against EV71 and CA16.
Evaluate the seropositivity rate of neutralizing antibodies against EV71 and CA16 at 6 months and 12 months after the full vaccination.
Time frame: 12 monthes
Evaluate the immunological persistence of the trial vaccine via the GMT of neutralizing antibodies against EV71 and CA16.
Evaluate the GMT of neutralizing antibodies against EV71 and CA16 at 6 months and 12 months after the full vaccination.
Time frame: 12 monthes
Evaluate the seroconversion rate of neutralizing antibodies against CA16 and EV71 in populations with a history of EV71 vaccination.
On the 30th day after full vaccination, evaluate the seroconversion rate of neutralizing antibodies against CA16 and EV71 in populations with a history of EV71 vaccination.
Time frame: 60 days
Evaluate the seropositivity rate of neutralizing antibodies against CA16 and EV71 in populations with a history of EV71 vaccination.
On the 30th day after full vaccination, evaluate the seropositivity rate of neutralizing antibodies against CA16 and EV71 in populations with a history of EV71 vaccination.
Time frame: 60 days
Evaluate the GMT of neutralizing antibodies against CA16 and EV71 in populations with a history of EV71 vaccination.
On the 30th day after full vaccination, evaluate the GMT of neutralizing antibodies against CA16 and EV71 in populations with a history of EV71 vaccination.
Time frame: 60 days
Evaluate the GMI of neutralizing antibodies against CA16 and EV71 in populations with a history of EV71 vaccination.
On the 30th day after full vaccination, evaluate the GMI of neutralizing antibodies against CA16 and EV71 in populations with a history of EV71 vaccination.
Time frame: 60 days
Evaluate the cross-immunogenicity of the trial vaccine against CA6 and CA10 via seroconversion rate of neutralizing antibodies against CA10 and CA6.
On the 30th day after full vaccination, assess the seroconversion rate of neutralizing antibodies against CA10 and CA6.
Time frame: 60 days
Evaluate the cross-immunogenicity of the trial vaccine against CA6 and CA10 via seropositivity rate of neutralizing antibodies against CA10 and CA6.
On the 30th day after full vaccination, assess the seropositivity rate of neutralizing antibodies against CA10 and CA6.
Time frame: 60 days
Evaluate the cross-immunogenicity of the trial vaccine against CA6 and CA10 via GMT of neutralizing antibodies against CA10 and CA6.
On the 30th day after full vaccination, assess the GMT of neutralizing antibodies against CA10 and CA6.
Time frame: 60 days
Evaluate the cross-immunogenicity of the trial vaccine against CA6 and CA10 via GMI of neutralizing antibodies against CA10 and CA6.
On the 30th day after full vaccination, assess the GMI of neutralizing antibodies against CA10 and CA6.
Time frame: 60 days
Evaluate the cross-immunogenicity of the trial vaccine against different serotypes of enteroviruses, including EV71 and CA16.
In populations with and without a history of EV71 vaccination, assess the GMT of neutralizing antibodies against different serotypes of enteroviruses, including EV71 and CA16, on the 30th day after full vaccination.
Time frame: 60 days
Evaluate the vaccine efficacy of the trial vaccine compared to the control vaccine against infection cases of EV71, CA10, CA6, and other enteroviruses.
Evaluate the vaccine efficacy against EV71, CA10, CA6, and other enterovirus infection cases, confirmed by RT-PCR, in the entire population (including those with and without a history of EV71 vaccination) 14 days after full immunization. The vaccine's efficacy will be evaluated by monitoring the annual incidence rate of cases attributable to EV71, CA10, CA6, and other enterovirus infections, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) nucleic acid testing, following complete full immunization for 14 days until the end of two epidemic seasons.
Time frame: 2 years
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