Based on past experience, it is estimated that 1 or 2 people in 1 million (0.000198 percent) who receive the vaccine may die as a result, most often the result of postvaccinial encephalitis or severe necrosis in the area of vaccination (called progressive vaccinia).Given these risks, as smallpox became effectively eradicated and the number of naturally occurring cases fell below the number of vaccine-induced illnesses and deaths, routine childhood vaccination was discontinued in the United States in 1972 and was abandoned in most European countries in the early 1970s. Routine vaccination of health care workers was discontinued in the U.S. in 1976, and among military recruits in 1990 (although military personnel deploying to the Middle East and Korea still receive the vaccination). By 1986, routine vaccination had ceased in all countries. It is now primarily recommended for laboratory workers at risk for occupational exposure. However, the possibility of smallpox virus being used as a biological weapon has rekindled interest in the development of newer vaccines. The smallpox vaccine is also used to protect against monkeypox, of which the smallpox vaccine also protects against. Treatment
Smallpox vaccination within three days of exposure will prevent or significantly lessen the severity of smallpox symptoms in the vast majority of people. Vaccination four to seven days after exposure can offer some protection from disease or may modify the severity of the disease. Other than vaccination, treatment of smallpox is primarily supportive, such as wound care and infection control, fluid therapy, and possible ventilator assistance.
Prognosis
The mortality rate from variola minor is approximately 1%, while the mortality rate from variola major is approximately 30%.Ordinary type-confluent is fatal about 50–75% of the time, ordinary-type semi-confluent about 25–50% of the time, in cases where the rash is discrete the case-fatality rate is less than 10%. The overall fatality rate for children younger than 1 year of age is 40–50%. Hemorrhagic and flat types have the highest fatality rates. The fatality rate for flat or late hemorrhagic type smallpox is 90% or greater and nearly 100% is observed in cases of early hemorrhagic smallpox. The case-fatality rate for variola minor is 1% or less. There is no evidence of chronic or recurrent infection with Variola virus. In cases of flat smallpox in vaccinated people, the condition was extremely rare but less lethal, with one case series showing a 66.7% death rate.In fatal cases of ordinary smallpox, death usually occurs between days 10-16 of the illness. The cause of death from smallpox is not clear, but the infection is now known to involve multiple organs. Circulating immune complexes, overwhelming viremia, or an uncontrolled immune response may be contributing factors. In early hemorrhagic smallpox, death occurs suddenly about six days after the fever develops. The cause of death in early hemorrhagic cases is commonly due to heart failure and pulmonary edema. In late hemorrhagic cases, high and sustained viremia, severe platelet loss and poor immune response were often cited as causes of death.