How can smallpox be prevented?
Emphasis must be placed on preventing epidemic spread. In doing so, it should be kept in mind that smallpox patients are not infectious during the early stage of the disease but become so from the first appearance of fever and remain so, though to a lesser degree, until all scabs have separated. Also, immunity develops rapidly after vaccination against smallpox. Surveillance of smallpox infection is probably easier than for any other infectious disease. A distinctive rash is produced
(see above) which is wholly characteristic in the great majority of cases. The rash is most dense over the face and hands – unclothed and readily visible portions of the body.
Experiences from the eradication campaign indicate that, in the presence of a strong surveillance system sensitive to smallpox cases and backed by an adequate infrastructure, small but rapid and thorough containment actions can break the transmission chain and halt a smallpox outbreak within a relatively short time. Containment involves efficient detection of cases and identification and vaccination of contacts. Patients diagnosed with smallpox should be physically isolated. All persons who have or will come into close contact with them should be vaccinated. As hospitals have proven to be sites of epidemic magnification during smallpox outbreaks, patient isolation at home is advisable where hospitals do not have isolation facilities. Whatever the policy, isolation is essential to break the chain of transmission.
Patients who developed rash before their isolation should be asked to recount all recent contacts. Contacts should be vaccinated. If it is not feasible to vaccinate contacts, they should be placed on daily fever watch, which should continue up to 18 days from the last day of contact with the case. If these contacts have two consecutive readings of 38 degrees centigrade or above, they should be isolated. All specimen collectors, care givers and attendants coming into close contact with patients should be vaccinated as soon as smallpox is diagnosed as the cause of an outbreak.
In the case of a widespread outbreak, people should be advised to avoid crowded places and follow public health advice on precautions for personal protection.
There is a vaccine to prevent smallpox that was routinely administered in the United States until the early 1970s. Routine vaccination of the civilian population for this disease is not currently recommended. The risk of adverse events resulting from the vaccine, accompanied by the rapid decrease in smallpox around the world in the 1970s, was part of the justification for the U.S. to discontinue routine vaccination against smallpox before the disease was eradicated in 1977. The vaccine is made from a virus called vaccinia, which is another "pox"-type virus related to smallpox. The vaccine helps the body develop immunity to smallpox. The vaccine does not contain the smallpox virus and cannot cause smallpox.
Getting smallpox vaccine before exposure will protect about 95 percent of people from getting smallpox. Vaccination within three days of exposure will prevent or significantly lessen the severity of smallpox in the vast majority of people. Vaccination four to seven days after exposure likely offers some protection from disease or may modify the severity of disease. Solid protection lasts for three to five years after vaccination. Partial protection lasts longer, but people need to be revaccinated if too much time has passed.
Until recently, the U.S. government provided the smallpox vaccine only to a few hundred scientists and medical professionals who work with smallpox and similar viruses in a research setting. After the events of September and October 2001, however, the U.S. government took further actions to improve its level of preparedness against terrorism. For smallpox, this included updating a response plan and ordering enough smallpox vaccine to immunize the American public in the event of a smallpox outbreak. The plans are in place, and there is sufficient vaccine available to immunize everyone who might need it in the event of an emergency.
Many people were vaccinated for smallpox in the past -- but the vaccination is no longer given because the virus has been eradicated. According to the CDC, the United States has supply of the smallpox vaccine sufficient for the entire population at this time. There are some complications associated with the vaccine, should the vaccine need to be given in the future to control an outbreak. Some of these are easily treated rashes, while other potential complications are more serious. The risk of complications is relatively low. (For example, the chance of encephalitis, which could be a fatal complication, is 1 out of 300,000). When smallpox was eradicated, the general population was no longer vaccinated because the potential complications and costs began to outweigh the benefits of taking it. The experience of vaccination of both military personnel and civilian health care workers in 2002-2003 suggested that the risk was very low but nonetheless present, and very small numbers of people had unforeseen reactions.