Some side effects are being reported from the smallpox vaccine.
Over the past several months, some 1,500 volunteers have participated in a study to test the controversial vaccine's safety.
Doctor Tom Talbott, who organized one study at Tennessee's Vanderbilt University, said scientists also want to find out how much they can dilute the vaccine and still have it work.
Talbott said everyone vaccinated develops a sore on the arm where it's injected. About one-third experienced swelling and redness. And about 10 percent experienced flu-like symptoms.
In the coming weeks, the White House is expected to announce a plan to vaccinate some Americans against smallpox.
The plan would reportedly call for vaccinations for some health-care and emergency workers, along with some military personnel.
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- The name smallpox is derived from the Latin word “spotted” and refers to the raised bumps that appear on the body of an infected person.
Forms of Smallpox
- Two forms of smallpox, variola major and variola minor.
- Variola Major: The sever and most common form of small pox, with a more extensive rash and higher fever. Four types of variola major smallpox:
- Ordinary: The most frequent type, accounting for 90 percent of the cases.
- Modified: Mild and occurring in previously vaccinated persons.
- Flat: Very fatal. Very hard to recover from this form of smallpox.
- Hemorrhagic: Very rare and most serious. Extremely fatal form of smallpox.
- Variola Minor: A less common presentation of smallpox, and a much less sever disease, with death rates historically of 1% or less.
Where Smallpox Originates From
- Smallpox is caused by the variola virus that emerged in human population thousands of years ago.
- Except for laboratory stockpiles, the variola virus has been eliminated.
- Direct and prolonged face-to-face contact is required to spread smallpox.
- 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.
Stages of Smallpox Disease
- Incubation Period (7-17 days, not contagious) – Exposure to the virus is followed by an incubation period, which people do not have any symptoms and may feel fine.
- Initial Symptoms (2-4 days, sometimes contagious) – The first symptoms of smallpox include fever, malaise, head and body aches, and sometimes vomiting. The fever is usually high, in the range of 101° F - 104° F.
- Early Rash (4 days, most contagious) – A rash emerges first as small red spots on the tongue and in the mouth. Usually the rash spreads to all parts of the body within 24 hours. As the rash appears, the fever usually falls and the person may start feeling better. However, by the fourth day, the bumps fill with a thick fluid, the fever will raise again and will last until scabs begin to form on the bumps.
- Pustular Rash (5 days, contagious) – The bumps become pustules, sharply raised, usually round and firm to the touch as if there is a small round object under the skin.
- Pustules and Scabs (5 days, contagious) – The pustules begin to form a crust and then scab. By the end of the second week after the rash appears, most of the sores have scabbed over.
- Resolving Scabs (6 days, contagious) – The scabs begin to fall off, leaving marks on the skin that eventually become pitted scars. Most scabs will have fallen off three weeks after the rash appears.
- Scabs Resolved (not contagious) – Scabs have fallen off. Person is no longer contagious.
Source: www.bt.cdc.gov (Public Health Emergency Preparedness and Response’s Web site) contributed to this report.