This is true for some vaccines, but it happens very rarely. The live oral polio vaccine (not used in the UK since 2004) did cause polio in a handful of cases. In rare cases, attenuated (live but weakened) vaccines can cause mild forms of the diseases they protect against. For example, the MMR vaccine very occasionally causes MEASLES, mumps or rubella, but the symptoms are almost always much milder than those caused by the diseases themselves.

This means that these KIND of vaccines are only really a risk to CHILDREN with weak immune systems (e.g. those with cancer), who have to RELY on protection from herd IMMUNITY.

This is true for some vaccines, but it happens very rarely. The live oral polio vaccine (not used in the UK since 2004) did cause polio in a handful of cases. In rare cases, attenuated (live but weakened) vaccines can cause mild forms of the diseases they protect against. For example, the MMR vaccine very occasionally causes measles, mumps or rubella, but the symptoms are almost always much milder than those caused by the diseases themselves.

This means that these kind of vaccines are only really a risk to children with weak immune systems (e.g. those with cancer), who have to rely on protection from herd immunity.