Childhood Shingles Resulting from Chickenpox Vaccination: “Rare” or Predictable?
From the inception of mass vaccination,
childhood vaccines have produced a raft of unintended consequences. One
of the biggest problems—gaining steam over the past several
decades—involves the vaccine-induced creation of brand-new risks and
vulnerabilities that can be more serious than the condition a given
vaccine might be intended to address.
The varicella (chickenpox) vaccine represents
a case in point. Chickenpox, usually mild when experienced in
childhood, was once a routine rite of passage. After the rollout of
universal varicella vaccination, the incidence of chickenpox declined
but observers began noticing a “’perverse’ boom” in
shingles (also called herpes zoster). Chickenpox and shingles
infections both stem from varicella zoster virus—and before the advent
of the varicella vaccine, children infected with chickenpox helped boost
adults’ immunity to shingles by inhibiting the latent virus’s
reactivation. Chickenpox vaccination disrupted this intergenerational
protective mechanism, not only eliminating regular boosting for adults
but shifting downward the average age at which shingles occurs. In addition , because varicella vaccine-induced immunity decreases by 8% with each year since vaccination,
previously vaccinated young adults are at increased risk for varicella
outbreaks and potential complications later in life. In short, while the
reduced circulation of wild chickenpox virus may spare some healthy
children a benign case of chickenpox, children now face the more serious
risk of developing shingles at young ages and chickenpox at older ages.
… the incidence of shingles in the U.S. rose by 63% among 10- to 19-year-olds as of the mid-2000s.
Predictions and case reports
When the Centers for Disease Control and
Prevention (CDC) added first one and then two doses of chickenpox
vaccine to the U.S. vaccine schedule (in 1996 and 2006, respectively),
numerous scientists predicted—accurately as things have turned out—that there would be a chickenpox-shingles tradeoff. In fact, the United Kingdom does not include the varicella vaccine in its childhood schedule to this day precisely because researchers there recognized the
potential for routine chickenpox vaccination to “drive up the age at
which those who are non immune get the illness” and increase the
incidence of shingles in all age groups. Confirming the initial
predictions, the incidence of shingles in the U.S. rose by 63% among 10- to 19-year-olds as of the mid-2000s.
Ordinarily, clinicians do not expect to
encounter shingles in children unless the children are seriously
immunocompromised. Perhaps this is why—in one case report after another
describing shingles in otherwise healthy vaccinated
children—researchers characterize the situation as “rare” or “unique.”
Even so, young shingles patients’ often dramatic clinical symptoms have
forced researchers to
acknowledge that shingles is definitely “possible” in children
vaccinated against varicella, and when they use appropriate molecular
analyses, they find that the vaccine-strain virus is the causative agent.
Across studies, the average age of shingles infection in children was 5.3 years, and the infection surfaced, on average, about three years after chickenpox vaccination.
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In 2017, clinicians
encountered shingles in a healthy 19-month-old who had received a
chickenpox vaccine six months previously, and they decided to put their
findings in context by searching the English-language literature for
similar cases. They identified roughly two dozen published cases of
vaccine-strain shingles in “immunocompetent” children and adolescents
who had received a chickenpox vaccine but otherwise had “no history of
varicella or exposure to varicella during gestation.” A number of the
studies reported shingles in very young children—such as a 15-month-old vaccinated three months previously, a 2-year-old “vaccinated for varicella at 17 months,” another vaccinated 2-year-old, and a 3.5-year-old girl who had received the chickenpox vaccine around age 2. Across studies,
the average age of shingles infection in children was 5.3 years, and
the infection surfaced, on average, about three years after chickenpox
vaccination.
Adverse events and complications
Young shingles patients experience a wide range of “rare but important adverse events.” Case reports have described:
- Lesions on the forehead, nasal bridge and upper and lower eyelids of a “previously healthy” 6-year-old boy who received the chickenpox vaccine at 1 year of age.
- Persistent shingles-related eye complications in a 6-year-old girl “with no medical history” who had been given two doses of chickenpox vaccine (at age 1 and again one year prior to the onset of symptoms).
- Headache, eye pain, eyelid rash and other symptoms in a 7-year-old boy who was “otherwise healthy and had received all of his scheduled vaccinations.”
- Ocular herpes zoster lesions and nerve palsy in an 8-year-old boy with “up-to-date immunizations” and an “unremarkable” medical history.
Unfortunately, shingles carries the risk
of even more serious complications, including the vision-threatening
eye condition called herpes zoster ophthalmicus—experienced by up to one in four persons with shingles. In a case series reporting
shingles in seven “immunized healthy children without underlying
immunodeficiency,” researchers described severe lesions as well as upper
respiratory symptoms and joint pain. Other major complications that may
occur either in tandem with rash or on their own include central nervous system problems such as encephalitis and meningitis. A 19-year-old female college student who had received two prior doses of varicella vaccine developed shingles-related encephalitis that
landed her in intensive care and resulted in lengthy hospitalization.
The strong antiviral drugs used to treat these conditions can cause kidney dysfunction. Mayo Clinic researchers report that asthma and atopic dermatitis both are associated with a higher risk of shingles.
At the same time, because the varicella vaccine is a live virus vaccine, people who get chickenpox vaccines can spread the vaccine-strain varicella-zoster-virus to others, a troublesome fact quietly acknowledged on the CDC’s website.
The “cost of success”?
Researchers at the University of British Columbia have suggested that
vaccine-associated shingles complications are just “one of the costs”
of the “success” achieved with universal chickenpox vaccination.
However, given that one in five children who receives the varicella
vaccine develops a “breakthrough”
chickenpox infection anyway, just what kind of “success” are we talking
about? In fact, “in communities with high vaccination coverage, varicella cases mostly occur in vaccinated individuals.”
At the same time, because the varicella vaccine is a live virus
vaccine, “[p]eople who get chickenpox vaccines can spread the
vaccine-strain varicella-zoster-virus to others,” a troublesome fact
quietly acknowledged on the CDC’s website.
When those “others” are young adults or older, the cases not
infrequently result in serious complications. Finally, it should be
noted that, as is the case with nearly all vaccines on the market, the
FDA approved varicella vaccines without any long-term safety testing—the
vaccines received a scant 42 days at most of monitoring after a single dose of vaccine.
In 2010,
CDC researchers identified yet another concern when they reported that
their laboratory had observed—in about 11% of the adverse events
resulting from varicella vaccination—“recombination between vaccine and
wild-type [varicella zoster virus] strains.” Moreover, the
“recombinants” demonstrated “a selective preference for reactivation,
enhanced replication, and/or an enhanced ability to traverse the nerve.”
The World Health Organization and other bodies have acknowledged that
this type of vaccine-plus-wild-virus recombination raises “unique safety issues.”
The CDC researchers noted that the shingles vaccines it now recommends
for older adults (“formulated at a virus concentration more than 14-fold
higher than that of childhood varicella vaccine”) are likely to
“substantially” increase the occurrence of “vaccine-wild-type recombination.”
It is time to bring “unintended” consequences out into the open and make sure they factor into all assessments of vaccine safety and efficacy.
Chickenpox vaccines are far from the
only type of vaccine to give rise to unintended consequences. In a
recent commentary, a leading pertussis expert admitted, for instance,
that pertussis vaccination actually increases vaccinated individuals’ lifetime susceptibility to pertussis. Merck’s highly flawed measles-mumps-rubella (MMR) vaccine (which relied on faked data to achieve Food and Drug Administration approval) has likewise backfired, prompting rampant fertility-threatening mumps outbreaks in
young adults. It is time to bring “unintended” consequences out into
the open and make sure they factor into all assessments of vaccine
safety and efficacy.
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