Vaccine shedding is the release or discharge of any of the vaccine components in or outside of the body and can only occur when a vaccine contains a live weakened version of the virus.
Contagious vaccinosis is the phenomenon where bystanders acquire symptoms of the immunizing / infectious agent after exposure to a vaccinated person. In the case of vaccination against a viral disease, it is explained either by (1) the vaccinated person developing a mild infection after vaccination, which can then be transmitted to another or (2) the shedding of virus, or viral particles, which airborne can be taken in by another.
Vaccines against viral disease that are known to shed include: MMR (measles, mumps, rubella), chickenpox, flu (intranasal only), shingles, rotavirus, and polio (the oral version of the vaccine only, which is not used anymore in the US).
Contagious vaccinosis was claimed as a cause of death by Covid-19 in Wuhan. It was argued that virus accumulating in sweat glands of a vaccinated person could be spread by perspiration; that concentrated virus then aerosolizes from the skin. Women who work with vaccinated women vaccinated against Covid-19 but who are themselves unvaccinated, have reported unusual changes to their menstrual cycle (dysmenorrhoea, amenorrhoea) similar to some vaccinated women.