Helicobacter pylori (H. pylori) is a Gram-negative, microaerophilic bacterium that persistently colonizes the human stomach; more than half the human population is infected worldwide. H. pylori infection is a risk factor for the development of gastritis, peptic ulcer, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer.

The phaseⅠand Ⅱclinical trial of oral recombinant Helicobacter pylori vaccine had completed in Jiangsu Province in China. The data from phaseⅠand Ⅱclinical trial suggested that the oral recombinant Helicobacter pylori vaccine had a clinically acceptable safety and good immunogenicity for health adults and children. To further explore the safety and immunogenicity profile of this vaccine, a phase Ⅲ clinical trial was conducted.

Helicobacter pylori (H. pylori) is a Gram-negative, microaerophilic bacterium that persistently colonizes the human stomach; more than half the human population is infected worldwide. H. pylori infection is the major risk factor for the development of gastritis, peptic ulcer, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer.

At present, the main clinical treatment for H. pylori infection is the application of antibiotics and bismuth agent or H+ antagonists. Due to the widespread drug resistance, toxic side effects, high medical costs as well as poor patient compliance, it is unworkable to practice antibiotics therapy for H. pylori eradication on every patient. Vaccination is the most effective way for prevention H. pylori infection.

Since H. pylori were found, great attention has been given to the H. pylori vaccine, scientists worldwide have made great efforts to develop both prophylactic and therapeutic H. pylori vaccine. Numerous H. pylori vaccine approaches have been studied, including inactivated whole cell H. pylori vaccine, genetic engineering subunit vaccine, live vector vaccines. Urease is considered to be an excellent candidate antigen for vaccine against H. pylori. However, no vaccine against H. pylori has been used in clinic.

The phaseⅠand Ⅱclinical trial of oral recombinant Helicobacter pylori vaccine had completed in Jiangsu Province in China. The data from phaseⅠand Ⅱclinical trial suggested that the oral recombinant Helicobacter pylori vaccine had a clinically acceptable safety and good immunogenicity for children. To further explore the safety and immunogenicity profile of this vaccine, a phase Ⅲ clinical trial was conducted.

Inclusion Criteria:

• Healthy children aged from 6-15 years old as established by medical history and clinical examination
• The subjects' guardians are able to understand and sign the informed consent
• Subjects who can and will comply with the requirements of the protocol
• Subjects with temperature <=37.0°C on axillary setting before vaccination

Exclusion Criteria:

Exclusion criteria for the first dose

• Subject who has a medical history of stomach illness
• Positive in either serology ELISA test for Helicobacter pylori diagnose kit or 13C urea breath test
• Subject who has suffered from heart, liver, and kidney disease
• Subject who has a medical history of any of the following: allergic history, or allergic to any ingredient of vaccine (for example: mannitol)
• Subject who is suffering from thrombocytopenia or other coagulation disorder
• Subject who has a diminished function of the immune system or autoimmune disease
• Subject who is suffering from congenital deformities, developmental disorders or serious chronic diseases
• Family history of seizures or progressive neurological disease
• Severe malnutrition or dysgenopathy, major congenital defects or serious chronic illness, including perinatal brain damage
• Any acute infections in last 7 days
• Any prior administration of immunodepressant or corticosteroids in last 6 month
• Any prior administration of other research medicines in last 1 month
• Any condition that in the opinion of the investigator, may interfere with the evaluation of study objectives

Exclusion criteria for the second and third dose Subjects will not be eligible for the second or third dose if any of following happened after first dose

• Subject who had allergic reaction to the last dose
• Any situation meet the exclusion criteria occurred after the last dose
• Subject who had any serious adverse events related to the vaccination
• Any condition that in the opinion of the investigator, may interfere with the evaluation of study objectives