Impact of Emerging Serotypes on Rotavirus Immunization

Abstract

Rotavirus infection is a universal disease that commonly affects children below the age of 5 years. The disease causes severe dehydration and may be fatal, especially in the younger age groups. In low socio-economic countries, the median age of infection is 6-9 months, and pre-existing co-morbid conditions, malnutrition, infections etc, make the population more vulnerable. The Rotavirus is a triple layered virus and has the VP4 and VP7 antigens which exist as different serotypes and genotypes. Re-assortment of the G and the P types gives rise to a multitude of viral strains, which vary with demographic variations. G1-4 and P4, P8 are the globally recognized strains. However, there are some new strains that have been noted with increasing frequency in India. These include G9P6, G9P11, G12P6, G12P4, which show varying degrees of isolation from various parts of our country. While the currently available licensed vaccines have shown dramatic results in decreasing the morbidity and mortality by both homotypic and heterotypic protection in low income countries like Brazil and Mexico where they were introduced in the national immunization schedule as early as 2006-2007, India is yet to introduce Rotavirus vaccines in the national immunization program. Despite the emergence of new disease causing strains, the existing vaccines continue to play a role in providing protection against severe Rotaviral infection in children.