Notes from
Sandy: "They found that the relative risk for seizures following aP
(acellular pertussis vaccine) was 0.85 on the day of vaccination, 0.76 on the
day after vaccination, and 0.95 at 2 to 14 days after vaccination. In contrast,
wP (whole cell pertussis vaccine) was associated with an increased relative
risk of seizures, 2.27, on the day of vaccination, which rose to 2.58 on the
day after vaccination.”
"Based on this data, aP should be substituted for wP vaccine, but we will
still need to determine whether aP causes fewer rare serious
adverse events," Dr. Hur told Reuters Health." (from article
below)
Gee, and I thought they said the whole cell vaccine was safe! (They also say they are rare with both vaccines, but it looks like they got the information from a passive reporting system, not active surveillance, so it may reflect only 1-2% of what is actually happening. It does seem as if there would be a higher % reported in this situation, since it was apparently those enrolled in 3 VSD HMO's (vaccine safety data link health maintenance organizations), whatever that means in real life. However, unless compared to active surveillance, i.e., following those who received a drug, as opposed to relying on people reporting reactions, we do not know for sure.)
Notice, by the way, two things, that were reported in the article below (perhaps the actual study went beyond what was reported) - one, that the risk of seizures with aP rose to its highest level from 2-14 days following vaccination. (We don't know if they were followed beyond then and what the results were, if they were.) And that the results for whole cell pertussis vaccine only were reported as far as the day following vaccination. (We don't know if they were followed beyond then and what the results were, if they were.)
According to the CDC at http://www.cdc.gov/nip/news/vacsafe.htm#2.1 :
"Q2.1
Under the Vaccine Injury Compensation Act, serious reactions are to be reported
through the Vaccine Adverse Events Reporting System (VAERS). It has been
estimated that only about 10 % of such reactions ultimately reach the FDA. What
proportion of vaccine adverse events are reported through VAERS?A. The
completeness of reporting isn't known and can't be expressed by a single
number. Research has shown that more serious events are more likely to be reported.
A recent CDC study examining the completeness of reporting found
reports for ~70 percent of vaccine-associated paralytic polio (VAPP), ~25-40
percent of seizures after DTP or MMR vaccines, and less than 5 percent for mild
events like rash after MMR vaccine. Under-reporting also may be greater for
events that occur longer after vaccination or which require a laboratory test
to diagnose (e.g., low platelet count after MMR vaccine). VAERS was designed to
encourage reporting in order to obtain the most complete information possible.
Many VAERS reports about serious health problems that happen around the time of
vaccination can be attributed to other causes not related to vaccines.
You may visit http://www.cdc.gov/nip/vaers.htm
for more information on the Vaccine Adverse Event Reporting System
(VAERS)."
However, former FDA
commissioner David Kessler stated in JAMA that it is thought only 1% of SERIOUS
adverse drug reactions may be reported to the FDA. And a
vaccine manufacturer testified that in their experience a passive system, which
is what VAERS is, results in just 2%. From reading his testimony I wasn't
sure, but think he may have even said that the distribution of events were the
same in active vs passive systems - which if that is what he said means that
only 2% of all events, even serious ones, are reported, in their
experience.
I would like to see the CDC
study in order to understand how they came up with the above figures of
"completeness". What groups did they use? Were they
randomly selected among all vaccinated? How large was the study?
Did they compare the incidence of these events to NEVER vaccinated
children? (Would provide a reference point, even though not normally
required for reporting.) Etc.
It points out the
importance of following ALL, 100%, of the vaccinated, actively, not
passively. The truth is, a passive reporting system results in
underreporting. No one questions that. What is questioned is the extent
of the underreporting. With universally recommended, even mandated,
vaccines, we owe it to our children to follow ALL of them. Sandy
Comment by Tim: The key to this article seems to be the last sentence...
Safety of Acellular Pertussis Vaccine Corroborated
--------------------------------------------------------------------------------
ATLANTA (Reuters Health) Apr 27 - Acellular pertussis (aP) vaccine is
less likely to cause seizures than whole cell pertussis (wP) vaccine,
according to a study of nearly a million children aged 2 years or
younger by the US Centers for Disease Control and Prevention (CDC).
Concerns about the safety of wP vaccine led to the development and
licensure of aP vaccines. Pre-licensure aP trials suggested a lower
rate of severe adverse events such as seizures, but according to the
researchers, these studies were smaller and of limited followup
duration.
Researchers led by Dr. Young J. Hur, of the CDC's National
Immunization Program, evaluated data from the CDC's Vaccine Safety
Datalink (VSD) to determine the safety of aP in a larger population.
They presented their findings here at the CDC's 50th annual Epidemic
Intelligence Service Conference.
Dr. Hur and colleagues analyzed computerized vaccination,
hospitalization, and emergency room data from 1992 to 1999 in a
cohort of 903,000 children aged 2 years or younger enrolled in three
VSD health maintenance organizations. By 1997, all HMOs had begun
using aP in the first year of life.
They found that the relative risk for seizures following aP was 0.85
on the day of vaccination, 0.76 on the day after vaccination, and
0.95 at 2 to 14 days after vaccination. In contrast, wP was
associated with an increased relative risk of seizures, 2.27, on the
day of vaccination, which rose to 2.58 on the day after vaccination.
"Based on this data, aP should be substituted for wP vaccine, but we
will still need to determine whether aP causes fewer rare serious
adverse events," Dr. Hur told Reuters Health.
"We will be looking in more detail at the difference in adverse
events between aP and wP," he said. "We will look at the effects in
older children - up to 7 years - and separate out febrile versus
afebrile seizures."
According to Dr. Melinda Wharton of the CDC's National Immunization
Program, the results of an unpublished study of older children
conducted by the National Institutes of Health indicate that
pertussis vaccination is equally as safe and efficacious in older
children.
"Prevention of pertussis is a challenging task," Dr. Wharton told
Reuters Health. "We know the vaccine appears safe, but what we don't
know is [to whom] pertussis vaccine should be given."
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