Rotaviruses like many RNA viruses display a great degree of diversity. Within group A, rotaviruses are classified into subgroups I, II, I+II and nonI, nonII, and 15 G and 20 P types, depending on the reactivities of antibodies to epitopes on VP6, VP7 and VP4, respectively and/or their gene diversity. As well as showing different G and P types and a variety of combinations of those, there is also intratypic variation.

Given that co-circulation of genetically diverse multitypic rotaviruses and of intratypic variants at any one place and time is common, and assuming widespread use of the vaccine in the near future, comprehensive surveillance of natural rotavirus infections is vital in order to allow judgements on:

The impact of vaccines in the general population.

Possible vaccine-induced emergence of antibody escape mutants within G1 to G4 serotypes.

The possible presence and/or emergence in the general population of serotypes other than G1 to G4.

The possible emergence in the general population of reassortants between vaccine and naturally circulating wild-type strains.

The degree of cross-protection provided (or not) by the vaccines.