If vaccines are safe and effective, why do those who have received live-virus vaccines, such as the chicken pox, measles, mumps, rubella, shingles, nasal flu, rotavirus, yellow fever, and possibly other vaccines, shed and spread the diseases for which they were vaccinated to others, for up to 6 weeks, perhaps for much longer? And since viral shedding by vaccine recipients of live-virus vaccines is a known and documented fact, why then are recipients of live-virus vaccines not required to self-quarantine, at home, until blood, saliva, and urine tests conclusively confirm that they are no longer capable of shedding and spreading the diseases for which they were vaccinated?