By DIEDTRA HENDERSON
AP Science Writer
October 12, 2004, 4:22 PM EDT
WASHINGTON -- Thousands of children immunized with a new vaccine to prevent pneumococcal infections such as meningitis and pneumonia suffered fever, fussiness, rashes, seizures and 117 died -- but the bulk of the reactions likely had nothing to do with the vaccine Prevnar, researchers reported Tuesday.
The research team said the reactions were similar to those seen with other vaccines.
The rashes, crying and fussiness, breathing difficulties, and stomach upset reported are "common childhood symptoms apart fromimmunizations," the researchers wrote in the Journal of the American Medical Association.
Serious events, including seizures, allergic reactions and abnormally low counts of platelets, a kind of blood cell, were rare, the researchers said.
"We know that Prevnar is a very safe and very effective vaccine," Dr.
Robert P. Wise, acting head of the Food and Drug Administration's
therapeutic and blood safety branch, and lead author of the report,
said in an interview.
The team looked for red flags in a database that would have revealed
worrisome safety trends with Prevnar, but found none.
"It's not pointing to anything," agreed Dr. Paul A. Offit, chief of Infectious Diseases at the Children's Hospital of Philadelphia and an expert on vaccine safety who was not involved in the research. "That's good. It makes biological sense."
The vaccine is a complex sugar hitched to a harmless protein and should be safe, Offit said.
The FDA cleared the seven-valent pneumococcal conjugate vaccine for
use on Feb. 17, 2000. It has rapidly become a routine shot that
pediatricians give in tandem with other childhood vaccinations. An
earlier study in JAMA attributed to the vaccine's use a drop in
childhood pneumonia and meningitis, more common among blacks than
whites.
In the first two years after the vaccine was used widely, researchers
found 4,154 adverse events -- among 31.5 million vaccine doses -- had
been reported to a national database. That amounts to 13.2 reports for
every 100,000 doses of vaccine distributed. The majority of the time,
children received multiple vaccine shots in a single setting.
Most complaints were minor -- fever, swelling at the injection site,
fussiness and rashes -- and had been seen in earlier clinical trials.
The 608 more serious events included 117 deaths and 34 instances in
which children suffered invasive pneumococcal infections, hinting at
vaccine failure.
The FDA was concerned about seizures, since clinical trials before the
drug was approved for use suggested a higher risk for such
neurological symptoms.
In the first two years of use, 393 seizures were reported. The
research team followed up on the first 98 seizure reports.
The vast majority were fever-related seizures or events in children
with a previous history of seizures, the authors wrote. Vaccination
may have played a role "in at least some" seizures. "Like other
vaccines, (Prevnar) can provoke fever, which could trigger a febrile
seizure," they wrote.
Wise said the single most important finding for parents was 14 cases
of serious allergic reaction days after Prevnar vaccination. Medical
attention was speedy and no child died. Such severe allergies can
occur with any vaccine, Wise said. In the Prevnar reports, one
ultimately was tied to infant formula.
"Many of the adverse events that get reported after vaccinations are
probably due to causes other than the vaccine," he said. "You have to
be quite cautious in interpreting data from these spontaneous
reports."
He said the agency's continued monitoring will keep close tabs on
adverse events that follow repeated vaccination. Children receive
multiple doses of Prevnar with catch-up doses suggested through age 9.
Having lowered platelet counts and severe allergic reactions after
repeat vaccinations heightens suspicion that the vaccine is
responsible, said Dr. Martin Myers, director of the National Network
for Immunization Information. "That adds more emphasis it might be
cause and effect."
The research team pointed to other limitations in the national
database, since many ailments are underreported and, in the face of
unexplained deaths, people are more apt to blame a new medication.
Still, the Vaccine Adverse Event Reporting System raised an early red
flag associating a different vaccine to a condition in which the
lining of the bowel folds, causing a blockage. The early warning
triggered follow-up studies that confirmed the vaccine link.
The vaccine manufacturer is completing a lengthy study that tracks
155,000 children in California. The group includes children immunized
as early as 1995. So far, no serious safety concerns have cropped up
among that larger group either, said Peter Paradiso, Wyeth vice
president of scientific affairs.
Knowing Prevnar -- like other vaccines -- can lead to fever gives
parents a chance to be pro-active, said Dr. Sharon G. Humiston, an
associate professor of emergency medicine and pediatrics at the
University of Rochester Medical Center.
Parents of children known to suffer febrile seizures should consider
ibuprofen with the vaccine. "Unlike the timing of fever from illness,
which is unpredictable, fever from vaccination is predictable,"
Humiston said.