The smallpox vaccine: Frequently asked questions
When can I get the vaccine?
In 2004, although the initial announcement in December 2002 mentioned that some vaccine might be made available in 2003 to people who "insist on being vaccinated."
If I was vaccinated when I was younger, am I still protected?
Probably not. Routine vaccination ended in the United States in 1972. The vaccine provides a high level of immunity for 3–5 years, but then protection starts to wane.
Has the vaccine changed since it was given routinely?
It's still made from live vaccinia, a pox-type virus related to smallpox. But Acambis, a British pharmaceutical company, is growing vaccinia in a new way that may make the vaccine safer. That vaccine is being tested in clinical trials and is expected to be available in 2004.
How is the vaccine given?
A small, forked needle is dipped into a bottle of the vaccine so that a drop is held between the prongs. Then the needle is jabbed into a small area of the upper arm about 15 times. The idea is to get the vaccinia virus into the body just under the skin, where it grows and produces an immune response to smallpox.
Is the vaccinia virus in the vaccine contagious?
Yes, it's a live virus, which is one of the reasons smallpox vaccination is riskier than other vaccines. People who've been vaccinated "shed" the vaccinia virus from the vaccination site for up to 19 days. People with eczema (atopic dermatitis) or compromised immune systems are especially vulnerable.
How does it spread?
In the past, most cases occurred only after close contact at home with the vaccinated person. Health officials hope that transmission can be limited by telling people to cover the vaccination site with a gauze bandage and put any used bandages in a sealed plastic bag.
Just how contagious is it?
In the 1960s, for every 100,000 Americans vaccinated for the first time, there were 2–6 cases of transmission. Today the numbers could be much higher. Most people are either unvaccinated or vaccinated too long ago. The eczema rate is two to three times higher than in the 1960s. Many more people have suppressed immune systems because of AIDS and medications for cancer treatment and post-organ transplant care.
How sick do people get?
Remember, the vaccine is vaccinia not smallpox. People have usually experienced only mild disease. But some young children have died after secondary transmission.
What about the risks for the person being vaccinated?
The normal reactions include some soreness where the vaccine was given, swollen glands in the armpits, and a low fever. In the past, about 1 in 1,000 developed more serious problems. The most frequent complication was a sore or rash on some other part of the body. People scratched the vaccination site, got the vaccinia virus on their fingers, and spread it to their face, eyelids, nose, mouth, genitalia, and rectum.
The virus can also spread through the blood from the vaccination site to other parts of the body. When that happens, people can get sores all over their bodies. And some people have had allergic reactions.
Potentially life-threatening events occurred in 14–50 out of every million people vaccinated, and 1–2 died.
Previous vaccination cuts the risk of serious consequences from the vaccine, but whether being vaccinated some 30 years ago will cut the risk is unknown.
With all these problems, is it worth the risk?
It's hard to say, which is one of the reasons for making the vaccine available on a voluntary basis; people can decide for themselves.
In a study posted in December 2002 on the Web site of the New England Journal of Medicine, researchers at the RAND Corporation predicted the number of deaths that would occur in various scenarios with and without widespread vaccination ahead of time. The scenarios ranged from a hoax to an accidental infection of a lab worker to the worst case: terrorists spreading smallpox virus at several airports.
The researchers estimated that if 60% of the American population were vaccinated, 500 deaths would result. Therefore, by their calculations, widespread vaccination would save lives only in the worst-case scenario.
May 2003 Update