Typhoid Vi Vaccine Effectiveness in Hechi, Guangxi, China

• vaccine effectiveness
• cost effectiveness of typhoid Vi immunization
• adverse events

• logistic feasibility of mass typhoid immunization
• anti-Vi antibody response
• knowledge, attitudes, beliefs and practices of parents and health care providers on typhoid fever prevention and treatment
• Typhoid risk factors

• logistic feasibility of mass typhoid immunization
• anti-Vi antibody response
• Knowledge attitudes, beliefs and practices of parents and health care providers on typhoid fever prevention and treatment
• Typhoid risk factors

This study is part of International Vaccine Institute (IVI)'s typhoid Vi demonstration project that aims to accelerate the rational introduction of Vi vaccines in typhoid endemic countries. The purpose of this study is to determine the effectiveness of the Vi vaccine following a mass typhoid immunization campaign in an endemic area in Hechi City in the Guangxhi province of China. The cost-effectiveness and safety of Vi vaccination will also be evaluated.

Typhoid fever is a major cause of morbidity worldwide. The disease predominantly affects school-aged children, is more prevalent in urban areas, may last for several weeks and can lead to serious complications. Management of this disease is further complicated by the emergence of multi-drug resistant strains. Vaccination of high risk populations is considered the most promising strategy for the control of typhoid fever. The Vi polysaccharide vaccine has been targeted for accelerated introduction into public health programs due to the following reasons: it has been shown to have consistent efficacy results even in areas of high typhoid incidence, is given as a single dose, lacks patent protection and requires less strict cold chain requirements.

This project attempts to evaluate a new vaccination strategy for residents of endemic areas. A cluster-randomized trial involving the Vi polysaccharide vaccine and an active control (meningococcal A vaccine) was designed to determine the effectiveness and the feasibility of providing Vi vaccine under actual programmatic conditions in 2 populous townships of Hechi City. The vaccines used in this study are locally produced and licensed in China. A 1 year pilot phase will precede the actual Vi-demonstration project. Surveillance for typhoid fever cases will continue after the mass immunization campaign. A passive surveillance system to evaluate adverse events following immunization will be implemented. Socio-economic studies will be conducted in parallel to the effectiveness evaluation. The knowledge, attitudes, beliefs and practices among parents and health care providers regarding typhoid illness, treatment and prevention will be assessed. Logistic, feasibility and vaccine costs will also be determined.

Secondary objectives of this trial are:

• To estimate the logistic feasibility of a mass typhoid immunization campaign
• To assess the knowledge, attitudes, beliefs and practices among parents and health care providers regarding typhoid illness, treatment and prevention
• To study typhoid fever risk factors in the population

• Typhoid
• Paratyphoid Fever

• Biological: Typhoid Vi vaccine
• Biological: Meningococcal A (control)

• Dong BQ, Yang J, Tang ZZ, Yang HH, Zeng J, Zhang J, Wang ML, Liang GC, Si GA, Li CY, Liang DB, Liao HZ, Ochiai RL, Mohammad A, Acosta CJ, Clemens J. [Application of cluster randomization method on typhoid Vi vaccine trails] Zhonghua Liu Xing Bing Xue Za Zhi. 2005 Feb;26(2):97-100. Chinese.
• Yang J, Acosta CJ, Si GA, Zeng J, Li CY, Liang DB, Ochiai RL, Page AL, Danovaro-Holliday MC, Zhang J, Zhou BD, Liao HZ, Wang ML, Tan DM, Tang ZZ, Gong J, Park JK, Ali M, Ivanoff B, Liang GC, Yang HH, Pang T, Xu ZY, Donner A, Galindo CM, Dong BQ, Clemens JD. A mass vaccination campaign targeting adults and children to prevent typhoid fever in Hechi; expanding the use of Vi polysaccharide vaccine in southeast China: a cluster-randomized trial. BMC Public Health. 2005 May 18;5(1):49.
• Acosta CJ, Galindo CM, Ochiai RL, Danovaro-Holliday MC, Page AL, Thiem VD, Park JK, Park E, Koo H, Wang XY, Abu-Elyazeed R, Ali M, Albert MJ, Ivanoff B, Pang T, Xu ZY, Clemens JD. The role of epidemiology in the introduction of vi polysaccharide typhoid fever vaccines in Asia. J Health Popul Nutr. 2004 Sep;22(3):240-5.

Inclusion Criteria:

• Registered in the project census

Exclusion Criteria:

• Pregnant
• Lactating
• Fever > 37.5 degrees Celsius, axillary

• Centers for Disease Control and Prevention
• Hechi City Center for Disease Centrol
• Wellcome Trust
• University of Western Ontario, Canada