Rotavirus vaccines: how they work or don't work.

In 2004 and 2006, two new rotavirus vaccines - Rotarixtrade mark and RotaTeqtrade mark - were licensed worldwide. Both are live virus vaccines and are composed of either a monovalent attenuated human rotavirus or five bovine-human reassortant rotaviruses, respectively. Studies in humans and animals have reported correlations between rotavirus antibody levels and protection, the most consistent of which has been with rotavirus IgA. Cellular immunity was also found to have a role in protection after live rotavirus immunisation, particularly in mice. However, the primary importance of CD8+ T cells may be in resolution of infection and that of CD4+ T cells may be their helper function, particularly for antibody production. CD4+ T cells have been reported to have a more direct role in protection after mucosal immunisation with non-living rotavirus vaccines, possibly because of direct or indirect effects of the cytokines they generate. Immune effectors have overlapping functions, and protection against rotavirus by either live or non-living vaccines is probably enhanced by this redundancy.