Dec. 13, 2002, 2:19PM
Smallpox vaccine risky, doctors warn
By TODD ACKERMAN
Copyright 2002 Houston Chronicle Medical Writer
|
SMALLPOX PRIMER
|
|
Like several other biological agents, smallpox has been given high
priority by health officials as a risk to national security.
• Disease
High fever, aches and other symptoms give way to a chickenpoxlike
rash. During the rash phase, the patient is most infectious, passing
the virus through airborne saliva. Smallpox proves fatal to
one-third of unvaccinated people.
• History
The first recorded smallpox epidemic occurred in 1350 B.C. Until
vaccination began, virtually everyone contracted the disease in some
form. In 1796, Edward Jenner showed that an infection caused by
cowpox protected against the smallpox virus, and the practice of
inoculation became widespread.
• Eradication
In 1967, the World Health Organization began a global campaign to
eradicate the disease. The last naturally occurring case was in
Africa in 1977. The disease was declared eradicated in 1980.
• Vaccine
After 1980, vaccine production facilities were dismantled. The
government has 15.4 million doses of smallpox vaccine and hopes to
buy an additional 300 million.
• Bioweaponry
The virus may have first been wielded as a weapon during the 18th-
century French and Indian Wars, when British soldiers set off
epidemics by distributing infected blankets to American Indian
tribes. The Soviet Union grew large quantities for use in bombs and
missiles. The virus is stable in aerosol form, and infectious in
small doses.
Sources: American Medical Association; Center for Civilian
Biodefense Studies
•
How the vaccine works
|
Although the federal government is stressing the smallpox vaccine is
safe for healthy adults, local experts warned Thursday that unless there
is a clear terrorist threat, the risks outweigh the benefits for the
general public.
The day after President Bush announced he intends to offer the
vaccine to the public on a voluntary basis in 2004, Houston doctors of
infectious diseases said that while it's prudent to inoculate military
personnel and some health care and emergency workers, the shot isn't
necessary for most people.
"I'm not privy to government intelligence about how imminent a threat
might be, but this isn't a benign vaccine," said Dr. Ralph Feigin,
president of Baylor College of Medicine, head of a bioterrorism
preparedness committee appointed by Houston Mayor Lee Brown and an
expert on infectious disease. "Absent a legitimate threat, I wouldn't
recommend it to my children or grandchildren."
The vaccine provides protection from smallpox, one of history's great
scourges, for three to five years, with decreasing immunity thereafter.
But it also can cause serious adverse effects, including death. In the
past, between 14 and 52 people for every 1 million vaccinated
experienced potentially life-threatening reactions, and one or two died.
Bush will announce the plan today, after months of debate within the
administration about how to respond to the threat that terrorists or
hostile governments might use the smallpox virus on the battlefield or
against civilians. Administration officials said Wednesday the plan will
call for the immunization of military personnel and health care
officials to begin in January.
Under a plan the state submitted to the federal government Monday,
about 40,000 Texas health care workers -- 6,000 in Harris County -- will
be vaccinated in January. States will have 30 days to deliver the first
round of shots.
Smallpox was declared eradicated in 1980, and there have been no
routine vaccinations in the United States since 1972. But in recent
years, the United States has come to fear that smallpox could be a
potent biological weapon, and officials have identified several nations,
including Russia, Iraq and North Korea, as perhaps having hidden stocks.
Smallpox is classified as Category A agent, the greatest potential
threat for adverse public health impact.
Government officials have estimated that 500,000 military personnel
and 500,000 health care and emergency workers would be covered by the
plan's initial phases. Eventually as many as 10 million people involved
in law enforcement, health care and emergency response could be offered
the vaccine.
Dr. Ed Septimus, medical director of infectious diseases and
occupational health for the Memorial Hermann Health Care System, said
that he thinks "up to half" of health care and emergency workers
ultimately won't be vaccinated because they'll choose not to or because
screening will eliminate them. (Reasons for elimination include
allergies to the vaccine, pregnancy, serious skin conditions, weakened
immune system such as in HIV/AIDS, and cancer treatment.)
"That estimate is from casual conversations, not anything
scientific," said Septimus. "I just think that when people hear what the
vaccine could do to them, a lot aren't going to want to take it. It's a
tricky issue."
Earlier this month, fit young adults, many at medical schools, became
a little panicky after receiving the vaccine as part of a government
study. One-third missed at least one day of work or school, 75 had high
fevers and many were put on antibiotics because physicians worried their
blisters signaled a serious bacterial infection.
The most common serious reaction comes when the vaccine's live virus
-- vaccinia, a "pox"-type virus related to smallpox but milder --
escapes from the inoculation site, often because people scratch the site
and then touch themselves or someone else; transferred to the eye, it
can cause blindness.
The more serious reaction is encephalitis, which can cause paralysis,
permanent neurological damage or, in some cases, death.
Yet polls show most people would get the vaccine if given the chance,
a prospect that has public health saying people don't understand the
risks. As a result, federal health officials are considering a national
television ad campaign to help people decide.
Officials say it will be 2004 before there is enough of a newly
manufactured vaccine to offer it to the public. Existing stockpiles of
decades-old vaccines will be used for the first phases of vaccination,
but the vaccine for the general public was diluted from old supplies and
is still being studied. In addition, manufacturers need to produce more
of the drug, vaccinia immune globulin, that treats vaccine side effects.
U.S. Centers for Disease Control and Prevention officials will host
representatives from each state next week to train them to deliver the
vaccine. Those people will then train others in their states.
Unlike most modern vaccines, the smallpox vaccine is administered by
15 quick pricks that literally "establish an infection in your skin."
Within three to four days, a red itchy bump develops, followed by a
larger blister filled with pus. In the second week, the blister dries
and turns into a scab that usually falls off in the third week. During
the three weeks, many people experience flulike symptoms -- aches,
fever, rash, swelling, lethargy -- and terrible itchiness.
Smallpox is generally spread by contact with infected people, usually
fairly prolonged face-to-face contact, but it can also be passed on
through infected bodily fluids or contaminated objects such as bedding
or clothing. It is inhaled, and quickly goes to a person's bloodstream
or organs.
There is no treatment, and it kills 30 percent of those infected who
haven't been vaccinated. People can prevent infection if they are
vaccinated within four days of exposure, before symptoms appear.
No one knows how much immunity would be provided by vaccines given 30
or more years ago. In the days when smallpox was present in developing
countries, doctors told people who were vaccinated more than five years
before to get another shot. |
