Viral Shedding from Vaccines

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Viral Shedding from Vaccines

Mass immunizations in schools and communities

May actually endanger the immune deficient via vaccine shedding.


Shedding is when the live virus that is injected via vaccine, moves through the human body and comes back out in the feces, droplets from the nose, or saliva from the mouth. Anyone who takes care of the child could potentially contract the disease for some time after that child has received certain live vaccines. This was a huge problem with the oral polio vaccine (OPV), and was one of the reasons why it was taken off the market in the US. The OPV is still used in developing counties.


Secondary transmission happens fairly often with some of the live virus vaccines. Influenza, Varicella, and Oral Polio Vaccine (OPV) are the most common. On the other hand it may happen very seldom or not ever with the measles and mumps vaccine viruses. Here are the vaccines that shed or have been known to result in secondary transmission:


Measles Vaccine – Although secondary transmission of the vaccine virus has never been documented, measles virus RNA has been detected in the urine of the vaccinees as early as 1 day or as late as 14 days after vaccination. (1)

In France, measles virus was isolated in a throat swab of a recently vaccinated child 4 days after fever onset. The virus was then further genetically characterized as a vaccine-type virus. (2)


Rubella Vaccine – Excretion of small amounts of live attenuated rubella virus from the nose and throat has occurred in the majority of susceptible individuals 7-28 days after vaccination. Transmission of the vaccine virus via breast milk has been documented. (3)


Chicken Pox Vaccine – Vaccine-strain chickenpox has been found replicating in the lung (4) and documented as transmitting via zoster (shingles sores) (5) as well as “classic” chickenpox (6) rash post-vaccination.




(1) Detection of measles virus RNA in urine specimens of vaccinated persons – Rota et al., Journal of Clinical Microbiology, 1995 can be accessed at

(2) Detection of measles vaccine in the throat of a vaccinated child – Morefin, et al., Vaccine 2002, can be accessed at

3) Prescribing Information, MMRII vaccine, can be accessed at

(4) Quinlivan et al, J Infect Dis. 2006, Vaccine Oka Varicella-Zoster Virus can be accessed at

(5) Brunell, et al., J. of Pediatrics 2000, Chickenpox Attributable to a Vaccine Virus can be accessed at

(6) Sauerbrei et al., J Clin Microbiol. 2004, Genetic Profile of an Oka Varicella Vaccine Virus can be accessed at