The Smallpox Vaccine

What is the Vaccine?The smallpox vaccine uses a live virus, calledvaccinia that is closelyrelated to smallpox.Vaccinia cannot causesmallpox, but it doescause a different infectionat the site of theinoculation. This infectionis usually mild. It lasts for a few weeks,leaving you immune to smallpox.Unfortunately, the immunity wears off overtime, so if you are old enough to have beenvaccinated as a child, your immunity hasprobably worn off.Is the Vaccine Safe?Yes and no. Yes, the vaccine is much saferthan getting the actual disease. However, thevaccine itself often causes side effects. Inmost cases they are mild, but in a very fewcases they can be serious, even lifethreatening.What Are the Side Effects?The smallpox vaccine and the vaccinia virus init create a controlled infection in order to buildyour immunity. However, because it is still aninfection caused by a virus, there are a numberof reactions that may occur and risks you maybe exposed to. You may also expose thosenear you to these risks.Normal, Typical and Mild ReactionsThe vast majority of those vaccinated willsuffer no side effects at all, or very mild ones.• The arm where the vaccine was given maybe sore and red. A scar will often form at thesite.• The glands in the armpits may become largeand sore• The vaccinated person may run a low fever• One out of three people may feel badenough to miss work or have trouble sleeping.Almost all of these reactions will disappear within acouple of weeks, and will not require medicaltreatment.Serious ReactionsIn the past, about 1,000 people for every 1 millionpeople (0.1%) vaccinated for the first timeexperienced reactions that were serious, but not lifethreatening. These reactions may require medicalattention.• A widespread rash and outbreak of sores awayfrom the vaccination site, caused by the virusspreading throughout the blood.• An allergic reaction in response to the vaccineor its components.Life-Threatening ReactionsReactions this serious are rare. In the past, 14-52people per 1 million people(≤ 0.005%) vaccinated forthe first time experiencedpotentially life-threateningreactions. These requireimmediate medicalattention!• Serious skin rashes causedby widespread infection ofthe skin in people with skin conditions likeeczema or atopic dermatitis.• Infection of skin with tissue destructionfrequently leading to death.• Inflammation of the brainIt is expected that 1-2 people per million vaccinatedwill die from complications caused by the smallpoxvaccine.The smallpox vaccine does NOT contain the smallpox virus.It does NOT cause smallpox.