Vaccine Strain Measles Reported
There have been published reports of vaccine strain measles with clinical symptoms
that are indistinguishable from wild-type measles. 242 243
There are also a few reports of measles vaccine strain virus shedding and lab confirmed infection in children following
MMR vaccination. In 2002, there was a published report by researchers in France of “a
child presenting with fever 8 days after vaccination with a measles-mumps-rubella
vaccine. Measles virus was isolated in a throat swab taken 4 days after fever onset.
This virus was then further genetically characterized as a vaccine-type virus.” 244
In 2010, Eurosurveillance published a report about excretion of vaccine strain measles
virus in urine and pharyngeal secretions of a Croatian child with vaccine-associated
rash illness.245 A healthy 14-month old child was given MMR vaccine and eight days
later developed macular rash and fever. Lab testing of throat and urine samples
between two and four weeks after vaccination tested positive for vaccine strain measles
virus. Authors of the report pointed out that when children experience a fever and rash
after MMR vaccination, only molecular lab testing can determine whether the symptoms
are due to vaccine strain measles virus infection. They stated:
“According to WHO guidelines for measles and rubella elimination, routine
discrimination between aetiologies of febrile rash disease is done by virus
detection. However, in a patient recently MMR-vaccinated, only molecular
techniques can differentiate between wild type measles or rubella infection or
vaccine-associated disease. This case report demonstrates that excretion of
Schwartz measles virus occurs in vaccinees.”
In 2012, a report was published describing a healthy 15-month old child in Canada, who
developed irritability, fever, cough, conjunctivitis and rash within seven days of an MMR
shot.246
Blood, urine and throat swab tests were positive for vaccine strain measles
virus infection 12 days after vaccination. Addressing the potential for measles vaccine
strain virus transmission to others, the authors stated, “While the attenuated virus can
be detected in clinical specimens following immunization, it is understood that
administration of the MMR vaccine to immunocompetent individuals does not carry the
risk of secondary transmission to susceptible hosts.”
Not Known How Long Vaccine Strain Measles Virus Infection and Shedding Lasts
In 2013, Eurosurveillance published a report of vaccine strain measles occurring weeks
after MMR vaccination in Canada. Authors stated, “We describe a case of measles mumps-rubella (MMR) vaccine-associated measles illness that was positive by both PCR and IgM, five weeks after administration of the MMR vaccine.” The case involved a
two-year-old child, who developed runny nose, fever, cough, macular rash and
conjunctivitis after vaccination and tested positive for vaccine strain measles virus
infection in throat swab and blood tests. 247
Canadian health officials authoring the report raised the question of whether there are
unidentified cases of vaccine strain measles infections and the need to know more
about how long measles vaccine strain shedding lasts. They concluded that the case
they reported ”likely represents the existence of additional, but unidentified, exceptions
to the typical timeframe for measles vaccine virus shedding and illness.” They added
that “further investigation is needed on the upper limit of measles vaccine virus
shedding based on increased sensitivity of the RT-PCR-based detection technologies
and immunological factors associated with vaccine-associated measles illness and virus
shedding.”
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