Kittens are protected against many infectious diseases through compounds called antibodies, which they receive in the first few hours from their mother's milk (colostrum). Early vaccination is pointless because these antibodies prevent vaccines working properly. However, by about seven weeks the immunity provided by the mother begins to wear off. Some kittens do not have good protection from their mother and these may benefit from earlier vaccination. For most of the above diseases, kittens should be given their first vaccination at about 8-9 weeks of age and then given a second vaccination at about twelve weeks. Until your kitten has received all its injections and for a few days after, it should not mix with other cats unless you can be certain that they are free of disease.