Decrease in Hospital Admissions for Febrile Seizures and
Reports of Hypotonic-Hyporesponsive Episodes Presenting to Hospital Emergency
Departments Since Switching to Acellular Pertussis Vaccine in Canada: A Report
Nicole Le Saux, MD*,
Nicholas J. Barrowman, PhD,
Dorothy L. Moore, MD, PhD,
Sharon Whiting, MD*, David Scheifele, MD||
and Scott Halperin, MD¶ for Members of the Canadian
Paediatric Society/ Health Canada Immunization Monitoring Program–Active
* Department of Pediatrics, University of Ottawa,
Ottawa, Ontario, Canada
Group, Children’s Hospital of Eastern Ontario Research Institute, Ottawa,
Montreal Children’s Hospital,
McGill University Health Centre, Montreal, Quebec, Canada
|| British Columbia’s Children’s Hospital, Vancouver, British
¶ IWK Health Center, Halifax, Nova Scotia, Canada
Objective. Acellular pertussis vaccines were introduced with
the promise of an improved safety profile compared with whole-cell
vaccines. In 1997–1998, Canada adopted 1 combination acellular
pertussis vaccine, having previously used 1 particular combination
whole-cell pertussis vaccine. We hypothesized that the change would
result in a decrease in hospitalization rates for seizures and
reports of hypotonic-hyporesponsive episodes (HHEs) temporally
related to pertussis vaccination.
Methods. Active surveillance was performed between
1995 and 2001 by the Immunization Monitoring Program–Active monitors
at 12 hospitals using standard case definitions. Seizures had
to occur within 72 hours after immunization with a pertussis-containing
vaccine or 5 to 30 days after immunization with measles-mumps-rubella
vaccine. HHE episodes had to occur within 48 hours of receipt
of a pertussis-containing vaccine. Poisson regression models were
used to compare the average number of monthly admissions for seizures
and HHEs before and after introduction of the acellular pertussis
Results. We found a 79% decrease in febrile seizures
associated with receipt of pertussis vaccine but no significant
decrease in febrile seizures temporally related to
measles-mumps-rubella between 1995–1996 and 1998–2001. There was a
60% to 67% reduction in HHEs associated with pertussis-containing
vaccines between the same time periods, depending on case definition.
Conclusions. The risks of febrile seizures and HHEs
after pertussis-containing vaccine declined significantly with the
introduction of acellular pertussis vaccine in Canada. Active
surveillance systems are important for detecting trends in uncommon
adverse events after routine immunizations.
A quote from researcher David Geier, MD, PhD: "We went to
Atlanta," he continues, "to the CDC, and looked at the VSD [Vaccine Safety Data]
data. There is thimerosal-containing DTaP [diphtheria, tetanus and
pertussis vaccine] and thimerosal-free DTaP, so we asked a question: Among
children that got a minimum of either three consecutive
thimerosal-containing DTaPs or three consecutive thimerosal-free DTaPs, was
there a difference in the number of autism cases in the two groups? We found
mega differences. More than 20 times higher. The rate of autism in the children
that got more than three doses of thimerosal-containing DTaP vaccines was
much, much higher. Almost all the children that have autism in that group were
the ones that got the thimerosal-containing DTaP vaccine. The more
thimerosal the greater the cases of autism."
--O'Meara KP. CDC Study Raises Level of Suspicion.
Posted on Wed, Nov. 08, 2006 by Sun Herald.com
MSU studies safer vaccine
Current ones may damage
THE ASSOCIATED PRESS
STARKVILLE - Biologists at Mississippi State University are studying safer
vaccines for whooping cough, which can sometimes lead to brain damage or death.
Lakshmi Pulakat and Nara Gavini head up a research team that discovered a
mechanism in current vaccines that may trigger neurological damage among
whooping cough patients.
Whooping cough is caused by the bacterium Bordetella pertussis, which produces
various toxins upon infection, said Mary Hetrick, a member of the MSU research
team and a biological sciences doctoral student.
"Neurological damage is a dangerous after-effect among patients suffering from
whooping cough and also seems to affect infants vaccinated with DPT vaccine or
acellular vaccine," said Hetrick.
Hetrick said Pulakat and Gavini "have identified a novel mechanism by which the
pertussis toxin can exert its ill effects and contribute to brain damage.
Since this mechanism is significantly different from the conventional
understanding of the action of pertussis toxin, this study provides new
possibilities to generate safer acellular vaccines to combat whopping cough,"
2006 The Sun Herald and wire service sources. All Rights Reserved.
Study: Whooping cough vaccination fades in 3 years
ATLANTA, Mon Sep 19, 05:02 PM
An empty bottle of Tetanus, Diphthera and Pertussis, (whooping cough) vaccine is
seen at Inderkum High School in Sacramento....More
The whooping cough vaccine given to babies and toddlers loses much of its
effectiveness after just three years - a lot faster than doctors believed - and
that could help explain a recent series of outbreaks in the U.S. among children
who were fully vaccinated, a study suggests.
The study is small and preliminary, and its authors said the results need to be
confirmed through more research. Nevertheless, the findings are likely to stir
debate over whether children should get a booster shot earlier than now
"I was disturbed to find maybe we had a little more confidence in the vaccine
than it might deserve," said the lead researcher, Dr. David Witt, chief of
infectious disease at the Kaiser Permanente Medical Center in San Rafael, Calif.
Witt presented his findings Monday at a medical conference in Chicago.
The study was done in California, where whooping cough vaccinations
are a hot-button issue. The state had a huge spike in whooping cough
cases last year, during which more than 9,100 people fell ill and 10
babies died after exposure from adults or older children. California
schools have turned away thousands of middle and high school students
this fall who haven't gotten their booster shot.
Government health officials recommend that children get vaccinated
against whooping cough in five doses, with the first shot at age 2
months and the final one between 4 and 6 years. Then youngsters are
supposed to get a booster shot around 11 or 12. That means a gap of
five to eight years.
Witt's study looked at roughly 15,000 children in Marin County,
Calif., including 132 who got whooping cough last year. He found that
youngsters who had gone three years or more since the last of their
series of shots were as much as 20 times more likely to become
infected than children who had been more recently vaccinated. The
largest number of cases was in children 8 to 12 years old.
Whooping cough, or pertussis, is a highly contagious bacterial
disease that in rare cases can be fatal. It leads to severe coughing
that causes children to make a distinctive whooping sound as they
gasp for breath.
Marin County has a reputation for anti-vaccine sentiment, and Witt
said that when he started the study he expected to see the illness
concentrated in unvaccinated people. But more than 80 percent of the
children who developed whooping cough in Witt's study were fully vaccinated.
California health officials told doctors last year that they could
give the booster to kids as young as 7 in an effort to stifle the
outbreaks. Federal health officials said that they are still studying
the issue and that it is too soon to make that a standard practice.
At the Centers for Disease Control and Prevention, which makes
recommendations on childhood shots, officials acknowledged that the
vaccine's protection declines, but they said the agency's own studies
show the drop-off is not as pronounced as Witt's research found.
The CDC has estimated that the risk of the disease can increase
fourfold several years after vaccination, not 10 to 20 times. One
reason may be differences in how a case is defined: Witt counted
positive test results, while the CDC also requires more than a week
CDC officials stressed that the vaccination is still much better than
nothing - it reduces how sick a child becomes. Also, the nation no
longer sees thousands of whooping cough deaths each year, as it did
before there was a vaccine.
The shots "are still our best protection against pertussis, and they
still protect well against fatal disease," said Dr. Tom Clark, who
leads the CDC's epidemiology team focused on vaccine-preventable diseases.
A vaccine using killed bacteria was used for decades, but the nation
switched over to a new type in the late 1990s that was seen as less
likely to cause the arm soreness, fever and more severe side effects
associated with the older version. The vaccine is typically given in
a combination shot that also protects against tetanus and diphtheria.
Periodic outbreaks still occur in places with high vaccination rates.
The short-term effectiveness of the vaccine has been shown to be 90
percent or higher in the first couple of years, and nearly every
state requires children to get the full series of shots before
enrolling in school. The long-term effectiveness is not well
understood, but researchers thought it was more than three years.
A preliminary study conducted by the CDC last year found the
five-dose vaccination for children was about 70 percent effective
five years after the last shot. Witt's research suggests the
effectiveness may drop much lower than that, perhaps below 50 percent
after just three years.
Witt also found that shots work great in the short term. Rates of
whooping cough dropped dramatically after kids were age 11 and 12,
when many get the booster shot.
The long-term effectiveness of that booster also is not known and has
received relatively little study. Health officials are also
discussing whether additional boosters may one day be recommended for
teenagers or adults.
"It's a little too soon to say much" about the longer-term
effectiveness of that booster, said Lara Misegades, a CDC epidemiologist.
IN OTHER WORDS, THEY DON'T WORK....
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