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People with smallpox are contagious only after they begin to get the awful rash that gives the disease its name. This means that once an outbreak is known to be under way, people with the rash are unlikely to infect anybody except for caregivers. These are the people who first should get the vaccine.
During very small outbreaks, patients can be kept in isolated hospital rooms. In larger outbreaks, patients would have to be kept at home. In either case, limited vaccine supplies would be rationed to the people surrounding each case. This strategy worked in previous outbreaks prior to smallpox eradication. Even then -- when most of the population had been vaccinated as children -- there was terrific pressure for mass vaccinations. Controlling mass panic is the most troublesome aspect of dealing with a smallpox attack. If sufficient vaccine is not on hand, some experts fear that the government will have no option other than forcible quarantine of exposed people.
Once the U.S. government has its 300 million doses of smallpox vaccine, the question is what to do with it. Some experts favor routine vaccination for everyone preemptively; others would reserve the vaccine to use only in the event of an outbreak.
The smallpox vaccination isn't completely safe. In the U.S. in 1968, for example, some 14 million people received the vaccine. That year there were 572 bad reactions resulting in nine deaths -- more people than have died so far in the current anthrax bioterror attack. In those days, bad reactions were treated with serum (a component of blood) from people who recovered from infection with smallpox -- and now this serum is in very short supply.
Unknown is what effect vaccination might have on people whose immune system isn't working right -- such as those with HIV infection or those taking immune-suppressing drugs for arthritis. Pregnant women also are at increased risk of bad reactions to vaccination. However, these populations also would be at increased risk of fatal smallpox -- so the risk of vaccination would have to be weighed against the risk of infection.
Other smallpox facts:
- Routine smallpox vaccination ended in 1972. The military stopped vaccinating its personnel in 1990.
- Vaccine protection lasts for about 10 years in those who receive a single dose -- so most people vaccinated as children are no longer immune. People vaccinated twice appear to be protected for 30 years. Laboratory workers who handle smallpox get vaccinated every 10 years.
- People who received at least one smallpox vaccination probably would get less serious disease if infected. In the case of a major smallpox attack, with too little vaccine to go around, these people might be called upon to care for the sick.
- Destruction of remaining smallpox stores in the U.S. and Russia was postponed to determine whether there is any scientific use for the virus. Some researchers think the virus might teach us a few things. Others (Henderson chief among them) say that the risk of keeping the virus far outweighs any possible benefit.
- If released into the environment, smallpox would be undetectable. It can survive in the air only for 24 hours under the best of conditions. Because it usually takes an infected person 12 to 14 days to develop symptoms, it would be very hard to trace an aerosol release.
- The bed sheets and clothing of people with smallpox can be infectious for extended periods after contamination. Such laundry must be handled with care and washed in hot water to which bleach has been added.
- Smallpox scabs contain infectious virus for as long as 13 years, but they do not release the virus into the environment. This is because the virus gets trapped in the scab.