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, 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 characterised 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 transmtting via zoster (shingles sores) (5) as well as “classic” chickenpox (6) rash post-vaccination.
Oral Polio Vaccine (OPV) – In areas of the world where OPV is still used, children who have been vaccinated with it pass the virus into the water supply through the oral/feces route. Other children who then play in or drink that water pick up the vaccine viruses, which can pass from person to person and spark new outbreaks of polio. (7) *
FluMist Vaccine – The mist contains live attenuated influenza viruses that must infect and replicate in cells lining the nasopharynx of the recipient to induce immunity. Vaccine viruses capable of infection and replication can be cultured from nasal secretions obtained from vaccine recipients.
Transmission of a vaccine virus from a FluMist recipient to a contact was documented in a pre-licensing trial. The contact had a mild symptomatic Type B virus infection confirmed as a FluMist vaccine virus. (8)
Rotavirus Vaccine (RotaTeq) – There is a possibility that one strain of rotavirus which is presently circulating may be an “escaped” vaccine strain, from an old Finnish rotavirus vaccine. (9)
Following are excerpts from the discussion by the FDA Advisory Committee on RotaTeq vaccine shedding: (10)
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 characterised 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 transmtting via zoster (shingles sores) (5) as well as “classic” chickenpox (6) rash post-vaccination.
Oral Polio Vaccine (OPV) – In areas of the world where OPV is still used, children who have been vaccinated with it pass the virus into the water supply through the oral/feces route. Other children who then play in or drink that water pick up the vaccine viruses, which can pass from person to person and spark new outbreaks of polio. (7) *
FluMist Vaccine – The mist contains live attenuated influenza viruses that must infect and replicate in cells lining the nasopharynx of the recipient to induce immunity. Vaccine viruses capable of infection and replication can be cultured from nasal secretions obtained from vaccine recipients.
Transmission of a vaccine virus from a FluMist recipient to a contact was documented in a pre-licensing trial. The contact had a mild symptomatic Type B virus infection confirmed as a FluMist vaccine virus. (8)
Rotavirus Vaccine (RotaTeq) – There is a possibility that one strain of rotavirus which is presently circulating may be an “escaped” vaccine strain, from an old Finnish rotavirus vaccine. (9)
Following are excerpts from the discussion by the FDA Advisory Committee on RotaTeq vaccine shedding: (10)