Delivery of vaccines

Most new vaccine candidates now target the Expanded Program on Immunization programme for delivery to children because of its extensive coverage in Developing Countries, over 80% in some cases.  This approach is not without some concerns: the childhood immune system may be overloaded by yet another vaccine, and there is an added danger of negative interactions between vaccines.

New vaccines are being developed which do not require a cold chain or which can be given by mouth rather than injection.