Vaccines for rotavirus gastroenteritis universally needed for infants.

Rotavirus causes severe and often lifethreatening illness. Universal application of a safe and protective vaccine is justified in both developed and developing nations. Two vaccine candidates, one monovalent (Rotarix) and one multivalent (Rotateq), appear to meet these requirements and are likely to be licensed in the United States in the next 2 or 3 years. Both vaccines exhibited similar safety characteristics. There is little doubt that Rotateq and Rotarix will be shown to be effective for routine protection of infants. Unfortunately, despite numerous clinical trials, the most common serotype (PlaGa) commonly has been encountered as a natural challenge. Therefore, it is not known whether either vaccine possesses advantages in different epidemiological situations. Continuing the analogy with influenza virus, it may be that optimum protection against different serotypes requires a vaccine that is precisely homologous in antigen composition. If so, Rotateq would provide protection against the most common serotype PlaG1 because in includes both Pla and G1 rotavirus reassortants. Further, it would be expected to provide superior protection against G2, G3, and G4 wild-type virus because it contains reassortants of those specificities. In the case of a natural challenge with a serotype that was not G1, G2, G3, or G4, a Rotateq preparation containing a WC3 reassortant expressing the new G serotype could be formulated readily. The monotypic Rotarix may provide ideal protection against the PlaG1 rotavirus because it is composed solely of the PlaG1 strain. It may also provide cross-protection against other rotavirus serotypes adequate to protect against severe and life-threatening disease. In such a case, its monotypic composition may also provide significant economic savings in manufacturing. The resolution of these questions may have to await extensive post-licensure experience with each vaccine. In the future, possible application of rotavirus vaccine for other situations also should be explored, including use in older children to limit nosocomial infection, use in geriatric populations, use in the immunocompromised host, and possibly use in parents and other adults in contact with infants with rotavirus. Both Rotarix and Rotateq likely are to be launched at prices beyond those affordable in the poorest and neediest less-developed countries. It is essential that there be vigorous pursuit of new technologies to manufacture these products at drastically reduced cost if their true lifesaving potential is to be achieved.