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The Disease

Smallpox is a serious, contagious, and sometimes fatal infectious disease. There is no specific treatment for smallpox disease, and the only prevention is vaccination. The name smallpox is derived from the Latin word for “spotted" and refers to the raised bumps that appear on the face and body of an infected person.

There are two clinical forms of smallpox. Variola major is the severe and most common form of smallpox, with a more extensive rash and higher fever. There are four types of variola major smallpox:

  • Ordinary (the most frequent type, accounting for 90% or more of cases);
  • Modified (mild and occurring in previously vaccinated persons);
  • Flat; and hemorrhagic (both rare and very severe).

Historically, variola major has an overall fatality rate of about 30%; however, flat and hemorrhagic smallpox usually are fatal. Variola minor is a less common presentation of smallpox, and a much less severe disease, with death rates historically of 1% or less.

Smallpox outbreaks have occurred from time to time for thousands of years, but the disease is now eradicated after a successful worldwide vaccination program. The last case of smallpox in the United States was in 1949. The last naturally occurring case in the world was in Somalia in 1977. After the disease was eliminated from the world, routine vaccination against smallpox among the general public was stopped because it was no longer necessary for prevention.

Where Smallpox Comes From

Smallpox is caused by the variola virus that emerged in human populations thousands of years ago. Except for laboratory stockpiles, the variola virus has been eliminated. However, in the aftermath of September and October 2001, there is heightened concern that the variola virus might be used as an agent of bioterrorism. For this reason, the U.S. government is taking precautions for dealing with a smallpox outbreak.


Generally, direct and fairly prolonged face-to-face contact is required to spread smallpox from one person to another. Smallpox also can be spread through direct contact with infected bodily fluids or contaminated objects such as bedding or clothing. Rarely, smallpox has been spread by virus carried in the air in enclosed settings such as buildings, buses, and trains. Humans are the only natural; hosts of variola. Smallpox is not known to be transmitted by insects or animals.

A person with smallpox is sometimes contagious with onset of fever (prodrome phase), but the person becomes most contagious with the onset of rash. At this stage the infected person is usually very sick and not able to move around in the community. The infected person is contagious until the last smallpox scab falls off.

About Smallpox Vaccine

Smallpox was declared eradicated in 1980 following a successful worldwide vaccination program. No one on earth has contracted natural smallpox since 1977. The last case of smallpox in the U.S. was in 1949. In the U.S., routine vaccination among the general public was discontinued in 1972, when it was recognized that the risk of serious adverse reaction (including death) from the vaccine outweighed the actual threat of disease.

The smallpox vaccine helps the body develop immunity to the virus. The vaccine is made from a closely related virus called vaccinia. The vaccine does not contain the smallpox virus, and cannot give the vaccinated person smallpox disease. According to CDC, the first dose of the vaccine provides protection for three to five years, and decreasing immunity thereafter. If a person is vaccinated again later, immunity lasts longer. Historically, the vaccine has been effective in preventing smallpox infection in 95 percent of those vaccinated.

There is no proven treatment for smallpox disease, but research to evaluate new antiviral drugs is ongoing. According to CDC, vaccination within three days of exposure will prevent or greatly lessen the severity of symptoms in the vast majority of people.

For most people, smallpox vaccine has been safe and effective. But because it is produced from a living virus, vaccinia, the vaccine may be harmful in some people. In the past, between 14 and 52 people per 1 million vaccinated experienced potentially life-threatening reactions. Careful screening of potential recipients is essential to ensure that those at increased risk do not receive the vaccine.

Women who are pregnant or planning to become pregnant, people with a history of eczema or atopic dermatitis or who currently have active skin conditions, people living with HIV/AIDS, organ transplant recipients, people receiving chemotherapy treatment, or who have household members with any of these conditions should NOT be vaccinated, unless they have been exposed to smallpox. In addition, women who are breastfeeding should not be vaccinated.

Smallpox Vaccine Clinic Information

The pre-event (no confirmed case(s) of smallpox disease) vaccination program will proceed in three stages:

Stage 1 would offer vaccine to designated health professionals across the nation who would make up the first public health and medical response teams. This includes personnel in hospitals who might first come in contact with an infected patient. It also includes those public health personnel who would be assigned to investigate cases, track contacts, vaccinate people, and institute measures to control the spread of disease.

Stage 2 would expand the offer of vaccination to a broader group of health care and public safety workers nationally, including law enforcement, emergency medical services, firefighters and HAZMAT teams. These are individuals approximately 125,000 in Connecticut, who are potentially at greater risk of coming into contact with smallpox than the general public.

Stage 3 would potentially offer smallpox vaccination to all United States residents at a later date.

Connecticut's plan provides a blueprint for how the state will carry out stage 1 pre-event vaccination, and reflects the coordinated planning among DPH, the hospital-based Centers of Excellence for Bioterrorism Preparedness and Response, and local health departments throughout the state. Public health officials emphasize that whether smallpox vaccinations are provided prior to an outbreak or in response to one, the decision to be vaccinated is a personal and voluntary one.

Because smallpox was eradicated in the 1970's, the President will consider a single case of smallpox an act of terrorism and likely result in the declaration of a National Emergency. To minimize potentially severe public health consequences associated with the introduction of smallpox, there will be the need to vaccinate the population of Connecticut within 10 days. In Connecticut, state and local health officers have defined smallpox planning areas and are developing plans that identify clinic locations and staffing.

Across the state, local health officials are conferring with their colleagues in town offices, police, fire, school superintendents, local planning councils, VNA's etc, to complete site selection and preliminary arrangements. Those towns without full-time health departments (i.e., a part time health director) are being grouped together with adjacent towns to share a site. South Windsor is one such town and will be joining with Windsor to operate a mass vaccination clinic, if and when it becomes necessary.

Additional Information

For more information about smallpox and smallpox vaccine and vaccination clinics, please contact the Windsor Health Department at 285-1827.