By LINDSEY TANNER : AP Medical Writer
Jun 24, 2003 : 4:00 pm ET
CHICAGO -- Heart muscle inflammation should
be added to the list of serious but uncommon side effects linked to
smallpox shots, a U.S. military study found.
The study details 18 cases of probable
myopericarditis out of 230,734 military personnel vaccinated between
December 2002 and mid-March. The rate is more than triple the
expected rate in nonvaccinated people and translates to at least 78
cases per million people.
Updated figures show 37 cases out of 450,293
military people vaccinated through May 28, a similar rate.
All patients recovered and are being
evaluated to see whether there are any lasting effects on the heart.
The other known side effects from smallpox
shots may include soreness at the injection site, fever and muscle
aches. Less common but more serious reactions include a widespread
skin rash, and -- rarely -- encephalitis, an inflammation of the
brain. Government data show only one civilian and one military case
of encephalitis were reported through May.
A federal advisory panel last week
recommended against expanding the civilian smallpox program to
millions of emergency workers because of concerns about heart
inflammation. The panel cited at least 18 suspected cases among some
37,000 civilian health care workers vaccinated so far.
The military study appears in Wednesday's
Journal of the American Medical Association.
It is one of several published in JAMA
detailing otherwise generally positive results from the military and
civilian smallpox immunization programs.
The studies found that serious side effects
are uncommon; one suggests they are rare even in some people with
immune system problems.
"The really important news is that it is
possible to conduct a mass smallpox vaccination in a safe and
effective manner," said Dr. William Winkenwerder Jr., assistant
secretary of defense for health affairs.
A JAMA editorial says the studies help
alleviate concerns that surfaced when the government began smallpox
programs for the military and some health care workers as part of
terrorism preparedness efforts. Routine smallpox immunization in the
United States ended in 1972.
Some experts had worried that the current
U.S. population might be more vulnerable to side effects from the
vaccine than people before 1972 because of increases in
immune-compromising conditions such as AIDS.
"The observation that this smallpox vaccine
can be administered safely in a 21st century population with a very
low adverse-event rate is a critically important piece of new
information," Drs. Anthony Fauci and Mary Wright of the National
Institute of Allergy and Infectious Diseases said in the editorial.
The overall rate of side effects in the
military was largely below the rates reported before 1972, one of
the studies found.
Myopericarditis causes inflammation of the
heart muscle and the fibrous tissue that envelops the heart. The
ailment probably occurred during smallpox vaccination in the 1960s,
too, but was underrecognized because diagnostic technology was less
sophisticated, military officials say.
Eight other heart-related events occurred
shortly after vaccination in the military program, including four
heart attacks, one of them fatal.
While military doctors think those were not
related to the vaccine, the risk prompted government officials to
recommend against giving the shots to people with heart conditions
or strong risks of heart disease.