Image: Smallpox
An electronmicrograph of the smallpox virus
msnbc.com

For months now, the government has warned Americans to prepare themselves for a biological or chemical attack. President Bush decided that the risk of a smallpox outbreak was significant enough to begin vaccinating health workers and members of the military. Thousands have already been inoculated, but questions still linger about the vaccine and its risks.

How does the smallpox vaccination campaign affect me?

Unless you’re a member of the military or a health worker chosen to receive the vaccine, the president’s smallpox plan will not have an immediate impact on you. However, the administration intends to make the vaccine widely available to the public by summer 2003, at which time ordinary citizens will be faced with a decision about whether to receive it.

Until then, Americans should educate themselves about the risks of vaccination versus the risks of an outbreak of smallpox itself. Researchers will be studying the effects of the vaccine on the soldiers and health workers who are receiving it first. It’s important to stay informed so that you’re better able to decide whether to get the vaccination when it becomes available and have a plan for what to do if an outbreak should occur in the meantime.

What is smallpox and why is it so worrisome?

Smallpox is a highly contagious virus that is spread from person to person, historically killing 30 percent of its victims and leaving survivors with permanent scars over large areas of their body, especially the face.

People can prevent infection if vaccinated within four days of exposure, before symptoms even appear; afterward, it’s too late, and there is no known treatment. The last case of smallpox in the United States was in 1949, and routine vaccinations ended in 1972. So most Americans born after then are completely unprotected.

Bioterrorism experts paint frightening scenarios like these: Terrorists release weaponized smallpox into the air in crowded places, or a dozen people on a suicide mission infect themselves with smallpox and, when they are at their most contagious, walk around airports, infecting others. This second scenario is somewhat undermined by the fact that people in the contagious stages of the disease generally are gravely ill and covered with sores that would likely arouse immediate suspicion.

Wasn’t smallpox wiped out?

The last naturally occurring case of smallpox in the world was in Somalia in 1977. In 1980, the disease was declared eradicated and all samples of the virus were to have been destroyed — except those held by special labs in Atlanta and Moscow. Experts worry that some of the Russian sample could have made its way to hostile nations, a fear that is amplified as the United States faces possible war with Iraq.

Smallpox is generally spread through direct, face-to-face contact from one person to another. The virus can also be transmitted through contact with contaminated objects, such as bedding or clothing, or through bodily fluids. It can also be carried in the air in enclosed settings, such as a bus, train or building. The virus cannot be transmitted by insects or animals.

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What are the symptoms of smallpox?

After a person is exposed to the virus, there are usually no symptoms for up to two weeks. At this point, the person will develop a high fever, experience fatigue, head and body aches, and sometimes begin vomiting. These symptoms last for two to four days. Then a rash will emerge on the tongue and in the mouth, spread to the rest of the body and develop into painful, raised sores that remain for three to four weeks. A person with smallpox should be considered contagious with the onset of fever, but they are most contagious once they have the rash. They remain contagious until the last smallpox scab falls off. f death comes, it usually occurs during the second week as a result of blood poisoning. Survivors face permanent scarring and possibly blindness.

Why not just vaccinate everyone now?

The smallpox vaccine is very effective and offers the only method of protection against smallpox, so the Bush administration plans to eventually offer it widely. But many experts are urging caution because the vaccine itself, made with a live virus called vaccinia, carries some serious risks, including the expected deaths of hundreds of people. In the past, when smallpox was known to exist among the population, the risks of vaccination were outweighed by the disease’s 30 percent risk of death. Now, the risk of infection from the virus is unclear so extra caution is being taken when considering subjecting the public to the dangers of inoculation.

What are the risks associated with the vaccine?

The smallpox vaccine is made with a live virus called vaccinia that carries rare but serious risks. Based on studies from the 1960s, experts estimate that 15 out of every million people vaccinated for the first time will face life-threatening complications, and one or two will die. Reactions are less common for those revaccinated.

For the approximately 130 million Americans never vaccinated, experts would expect nearly 2,000 to face life-threatening complications and 125 to 250 of them to die.

For about 158 million people being revaccinated, experts expect nearly 800 life-threatening complications and about 40 deaths.

Typical reactions include sore arms, fever and swollen glands. The most common serious reaction comes when vaccinia escapes from the inoculation site, often because people touch the site and then themselves or someone else. For instance, the virus transferred to the eye can cause blindness. The most deadly reaction is encephalitis, which can cause paralysis or permanent neurologic damage. Also fatal though very rare is progressive vaccinia, where the vaccination site does not heal and the virus spreads, eating away at flesh, bone and gut.

How do these side effects compare with other vaccines?

The smallpox vaccine is more dangerous than any other. By comparison, the measles-mumps-rubella shot can cause reactions including anaphylaxis, marked by swelling inside the mouth and difficulty breathing. But just 11 cases of anaphylaxis have been reported since 1990, out of more than 30 million vaccinations, and no one has died.

If I was vaccinated years ago, am I still protected?

The smallpox vaccine only provides full immunity for three to five years, but studies on people inoculated more than 35 years ago show that many of them still carry a significant amount of immunity to the virus. A recent report in the New England Journal of Medicine found that resistance to the disease among people vaccinated decades ago is waning but not rapidly. They still may contract the disease and develop symptoms, but they are less likely to die.

In the event of an outbreak, however, people who received the vaccine years ago should not assume they’re immune. They could still develop serious, life-threatening symptoms and pass the virus on to others.

How is the vaccine given?

The vaccine is administered using a two-pronged needle that is first dipped into the vaccine solution. The needle is used to prick the skin, usually on the upper arm, quickly 15 times over a few seconds. If the inoculation is successful, a red, itchy bump develops in three to four days. The bump turns into a large blister that fills with pus and begins to drain. Within two weeks, the blister dries up and a scab forms.

The vaccine does not contain smallpox virus and cannot spread or cause the disease. However, it does contain another live virus, called vaccinia, which can be spread to other parts of the body or other people. For this reason, the inoculation site must be carefully covered with bandages until the blister heals.

Is there anyone who should not get the vaccine?

Certain people with impaired immune systems or skin conditions are at increased risk for serious side effects from the smallpox vaccine. People who have any of the following conditions or live with with someone who does should not get the shot unless they are actually exposed to the smallpox virus:

  • A history of eczema or atopic dermatitis.
  • Burns, chickenpox, shingles, impetigo, herpes, severe acne or psoriasis. People with any of these conditions should not get the vaccine until they have completely healed.
  • Weakened immune system, such as cancer patients undergoing treatment, organ transplant recipients, people with HIV or those on medications to treat autoimmune disorders.
  • Pregnancy or plans to become pregnant within one month of vaccination.

Officials administering the vaccine will ask detailed questions to try to screen out such people. Some experts predict the rate of complications is likely to be much higher than it was in the past, when AIDS didn’t exist and there were fewer organ transplants. Still, screening is likely to be tighter, so the two factors could balance out.

Is the vaccine safe for kids?

Children in the United States were once routinely vaccinated against smallpox, but there are some concerns that parents should be aware of. As in the adult population, certain groups of children are at a higher risk of vaccine-related complications. For instance, a child who has immune problems or skin diseases could face severe complications. Babies under 1 year old are at a significantly higher risk of vaccine-caused brain infection.

In addition, inoculation sites on children should be covered with a special, extra-sticky bandage since kids are more likely to peel off the bandage and could pass the vaccine’s virus to other children.

Because of safety concerns, the government has said it will not offer the vaccine to children except in the event of a bioterror attack.

Is there enough smallpox vaccine available for everyone in the United States?

By diluting long-stored doses, the United States now has more than enough smallpox vaccine to protect everyone. Acambis Inc., a company based in Cambridge, Mass., has contracted with the government to make 209 million doses by next year. Should a smallpox attack occur before then, health officials will rely on stockpiles of two older smallpox vaccines, called Dryvax and Aventis Pasteur, which were produced 20 to 30 years ago. Studies show that these vaccines can be watered down and remain just as effective. There are currently 375 million diluted doses of Dryvax and Aventis Pasteur available to the government, more than enough to inoculate the entire U.S. population.

What if terrorists used a genetically engineered version of the smallpox virus?

If terrorists used a genetically engineered smallpox virus, it’s possible that the existing stockpile of smallpox vaccine could be useless, but scientists do not know this for sure. Researchers have inserted a gene called interleukin-4 into the mousepox virus, a relative of smallpox that is harmless to humans. The engineered virus became more deadly than the natural strain, killing mice that had been vaccinated against mousepox. Scientists aren’t sure if this result would also apply to the human smallpox virus, but it is a fear. Such a scenario emphasizes the importance of alternate means of containing smallpox, such as the development of new antiviral medications and the strict enforcement of a quarantine policy should an outbreak occur.

Will the vaccine be mandatory when it’s made available to the public?

No. Even in the middle of a smallpox attack, there are no provisions to force vaccinations, though people exposed to the disease who refuse to get vaccinated could be quarantined.

What would happen if there were a smallpox attack today?

The CDC smallpox response plan calls for immediate isolation of confirmed and suspected smallpox cases and tracing and vaccinating people who had been in close contact with the smallpox patients while they were contagious.

But depending on the size of the outbreak, state and federal officials might order vaccination of everyone in areas with confirmed cases and might impose quarantines in some places.

Is there a treatment for smallpox?

The smallpox vaccine can prevent the disease up to four days after exposure, but beyond that, there is no proven treatment. At this point, patients would be offered supportive therapy such as intravenous fluids and medicines to control fever, pain and secondary infections, until the disease ran its course. Research into possible treatments for the disease is on the fast track, with early laboratory studies suggesting the drug cidofivir may fight the virus.

If the vaccine is effective four days after exposure, why not just wait until after an attack for vaccination?

Delivering mass vaccinations within days is incredibly complicated, and an attack would be much less deadly if more people already were vaccinated. However, by vaccinating hundreds of thousands of first responders according to Bush’s plan, mass vaccination would be more feasible. States are currently in the process of planning post-attack vaccinations.

What are the pox viruses?

Smallpox is caused by the variola virus, a member of the orthopoxvirus family that also includes cowpox, monkeypox, mousepox, rabbitpox and camelpox among others.

Human cases of monkeypox — a disease very similar to smallpox — are sporadically seen in parts of Africa, usually transmitted to people from squirrels and primates through contact with the animal’s blood or through a bite.

Cowpox, a mild disease that used to infect milkmaids, is the source of the current smallpox vaccine, vaccinia. In 1796, Dr. Edward Jenner noticed that milkmaids who had contracted cowpox, from which they easily recovered, resisted infection from smallpox, suggesting that infection with a related, but not identical virus affords protection against the much more serious disease.

Camelpox appears to be innocuous in humans but some bioterror experts are concerned about the possibility that camelpox or other orthopox viruses could be modified for use as biological weapons. However, smallpox vaccination protects against all the orthopox viruses.

CDC public response hot lines:

  • English: (888) 246-2675
  • Espanol : (888) 246-2857
  • TTY: (866) 874-2646.

MSNBC’s Molly Masland, Julia Sommerfeld and The Associated Press contributed to this report.

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