On January 03, 2018, the World Health Organization (WHO) announced that it has prequalified Bharat Biotech's Typbar-TCVR1, the first conjugate vaccine for typhoid. Typhoid conjugate vaccines (TCVs) are innovative products that have longer-lasting immunity compared to older vaccines, require fewer doses, and can be given to young children through routine childhood immunization programs. Prequalification of the vaccine by WHO means that it meets acceptable standards of quality, safety and efficacy. This makes the vaccine eligible for procurement by UN agencies like UNICEF and Gavi - the Vaccine Alliance.
In October 2017, the Strategic Advisory Group of Experts (SAGE) on immunization, which advises WHO, recommended TCV for routine use in children over 6 months of age in typhoid endemic countries. SAGE also called for the introduction of TCV to be prioritized for countries with the highest burden of typhoid disease or of antibiotic resistance to Salmonella Typhi, the bacterium that causes the disease. Use of this vaccine is expected to help curb the frequent use of antibiotics for treatment of presumed typhoid fever; and thereby help to slow the alarming increase in antibiotic resistance in Salmonella Typhi.
Shortly after SAGE's recommendation, Gavi Board approved US$85 million in funding for TCVs starting in 2019. Prequalification is therefore, a crucial next step needed to make TCVs available to low-income countries where they are needed most. And even in non-Gavi-supported countries, prequalification can help expedite licensure. WHO prequalification helps to ensure that vaccines used in immunization programmes are safe, effective and appropriate for countries' need. WHO's prequalification procedure consists of a transparent, scientifically sound assessment that includes reviewing the evidence, testing the consistency of each lot of manufactured vaccine, and visiting the manufacturing site.
About Typhoid
Typhoid fever is a systemic infection caused by Salmonella Typhi, usually through ingestion of contaminated food or water. The acute illness is characterized by prolonged fever, headache, nausea, loss of appetite, and constipation or sometimes diarrhea. Symptoms are often non-specific and clinically non-distinguishable from other febrile illnesses. However, clinical severity varies and severe cases may lead to serious complications or even death. It occurs predominantly in association with poor sanitation and lack of clean drinking water. According to recent estimates from the WHO, approximately 21 million cases and 222 000 typhoid-related deaths occur annually worldwide2. Typhoid fever, results in reduced school attendance, loss of work and wages, lowered pregnancy outcomes and impaired physical and cognitive development of children. In most developing countries the cost of a course of treatment for typhoid fever ranges from $50 to $5000 for outpatient and inpatient treatments3.
Urbanization and climate change have the potential to increase the global burden of typhoid. In addition, increasing resistance to antibiotic treatment is making it easier for typhoid to spread through overcrowded populations in cities due to inadequate and/or flooded water and sanitation systems.
About Tybar TCV®
According to Bharat Biotech the manufacturer of this vaccine, Typbar TCV R is a Typhoid VI Capsular Polysaccharide Tetanus Toxoid Conjugate vaccine. The Typhoid VI Capsular Polysaccharide Tetanus Toxoid Conjugate vaccine stimulates specialized T cells in the human body. Engagement of T cells by VI conjugate vaccine results in superior and longer lasting antibody response, which helps in the prevention of typhoid disease not only in adults but also in children and infants4.
Typbar TCVR is the world's 1st clinically proven conjugate Typhoid vaccine. Further, the Typhoid Vi Capsular Polysaccharide Tetanus Toxoid Conjugate vaccine is the only approved vaccine for children and infants less than 2 years of age. During the Phase III clinical study, a single dose of Typbar TCV elicited 4-fold seroconversion rates of 98.05%, 99.17% and 92.13% in subjects between ≥6 months to 2 years, ˃2 to 15 years and ˃15 to 45 years respectively.
Typbar TCVR has been evaluated in several clinical trials, in several thousand healthy adults and children, across 21 sites in India and the United Kingdom. Active post marketing surveillance is ongoing and has been completed in more than 7000 subjects, since the vaccine was first launched in India in 2013.
Conclusion:
Enteric fever caused by Salmonella Typhi remains a major public health problem in various countries globally, and WHO pre-qualification of the new typhoid vaccine from an Indian manufacturer is an important event which is a true reflection of India's growing prowess in the global arena of pharmaceuticals, vaccines, and biotechnology.
The WHO prequalification of this vaccine also marks an important milestone in the global effort to rid the world of typhoid fever.
Footnotes
1 http://www.who.int/medicines/news/2017/WHOprequalifies-breakthrough-typhoid-vaccine/en/
2 http://www.who.int/immunization/diseases/typhoid/en/
3 http://www.bharatbiotech.com/wp-content/plugins/prs/pdf/Bharat-Biotech-TypbarTCV-WHO-PQ-Press-Release-India-F.pdf
4 http://www.bharatbiotech.com/products/vaccines/typbar-tcv-2/
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