Biography
Biography: Rohit Agrawal
Abstract
Introduction & Disease Burden:
Typhoid has a huge global burden with 21 million cases and over 200,000 deaths annually, the burden is more profound in developing world particularly in India [incidence 214.2/100,000].
Apart from huge burden and endemicity, three other major problems being: Poor hygienic conditions, sanitation, and over-crowding, Emergence of multi-drug resistant S-typhi and S-typhi H58clade and Changing scenario with children bellow 2 years getting equally affected.
Vaccines
The vaccines available in India are 2nd generation Vi- polysaccharide and 3rd generation Vi-polysaccharide conjugate vaccines
Vi-polysaccharide: poorly immunogenic, poor immunogenicity ,limited efficacy [60%]needs repeated doses, short duration protection and no effect < 2 years
Vi-Polysaccharide Conjugate Vaccines:
Currently two conjugate vaccines are available with 5 and 25 micrograms antigen. Various field trials for immunogenicity and efficacy showed more robust data in favor of 25 micrograms to the tune of 98.3% with 4 years follow-up studies. The vaccine is licensed for the age 6 months to 45 years. IAP-ACVIP recommends two doses at 9 months and 2 years with catch up vaccination up to 18 years. Need for a booster is a grey area due to scarcity of supporting data.
Conclusion: India being a highly endemic country for typhoid, with emerging MDR strains; certainly needs a cost-effective and highly efficacious vaccine which can be used on below two years of age. The new generation TCV vaccine is an ideal candidate