Abstract: Live virus vaccines comprise attenuated viruses, while other vaccines comprise killed viruses or parts thereof. It has now been found that the immune response induced by oral poliovirus vaccine (OPV), which is a live vaccine, is cross-reactive with non-polio enteroviruses. OPV is therefore useful in the prevention of non-polio enterovirus diseases, especially Type 1 diabetes mellitus (IDDM). OPV is also useful in combination with killed/subunit non-polio enterovirus vaccines, whereby it prevents harmful side-effects of the killed/subunit vaccine by shifting the immune response from a harmful Th2-type response to a Th1 type response.