or the
last eight years, the Food and Drug Administration has
repeatedly asked pharmaceutical companies not to use materials
from cattle raised in countries where there is a risk of mad cow
disease.
But regulators discovered last year that five companies,
including some of the world's largest drug concerns, were still
using ingredients from those countries to make nine widely used
vaccines.
Some of the companies say that they found the F.D.A.'s
request unclear and do not believe they did anything wrong.
Others say they could not keep up with the government's
expanding list of countries where cattle could be infected. One,
however, acknowledged that it could have moved more quickly.
The nine vaccines include some regularly given to millions of
American children, including common vaccines to prevent polio,
diphtheria and tetanus. They also include the anthrax vaccine,
which the government requires for soldiers serving in the
Persian Gulf.
Federal health officials stress that the vaccines are still
considered safe. They calculate that the odds of these vaccines
passing on the disease, in the worst eventualities, are between
one in 40 million and one in 40 billion doses.
The officials say that the very slight chance that someone
could be infected is far outweighed by the benefits that these
vaccines bring in fighting disease and preventing death. Indeed,
it is now only a scientific theory that a vaccine could infect
someone with the human form of mad cow disease — called new
variant Creutzfeldt- Jakob disease. No one is known to have
contracted the disease this way.
"Any risk is very remote," said Dr. Karen Midthune, director
of the F.D.A.'s Office of Vaccine Research and Review. "But if
we have the ability to bring this remote risk to zero, that is
something we want to do."
Nonetheless, the fact that these suspect materials slipped
into the nation's vaccine supply — and that the F.D.A. did not
discover it for seven years — raises questions about the
agency's ability to ensure that all medicines are free of the
infectious proteins that can cause mad cow disease.
The F.D.A. so far has only investigated the vaccine makers
and has not looked to see whether other medicine is free of
possible mad cow contaminants. Some experts say they worry more
about dietary supplements. Unlike drugs, supplements are largely
unregulated. The F.D.A. is not even sure how many supplement
makers there are.
"It's just insane not to have greater safeguards" for
supplements, said Dr. Paul W. Brown, chairman of the F.D.A.'s
advisory committee on mad cow disease. "The potential exists for
abuse."
All five vaccine makers, which include
GlaxoSmithKline, Aventis and American Home
Products, have now agreed to stop using the suspect
materials, which include blood, fetal calf serum and meat
broth.
But it will take a year or more to replace existing supplies
with reformulated products, because it can take many months to
grow cultures used in making vaccines. Both the companies and
the F.D.A. say that the current products are safe and should
remain on pharmacy shelves.
They point out that the suspect ingredients, for the most
part, are used only in the early stages of manufacturing, when
cultures are grown. Blood, for instance, may be used to feed the
bacteria and viruses in these cultures. The cultures are then
significantly diluted in the final vaccine.
