Adverse Reactions

Smallpox (vaccinia) vaccination is a generally safe, effective preventative against smallpox. However, in a number of individuals, smallpox vaccination can result in untoward effects and adverse reactions. Most are totally benign, if frightening in appearance. Some are serious, but treatable. A few, which rarely occur, are serious, life threatening and can be fatal. Click on any of the adverse reaction images or names at the right to read more about each adverse reaction, including who is susceptible and measures that might be employed to reduce risk to the vaccinee and his or her contacts.

Hospitalization
Hospitalization of patients with adverse events should be based on the degree of severity and infectiousness:

(1) Unless serious disease is present, such as Stevens Johnson Syndrome.

(2) Most patients with generalized vaccinia will not require hospitalization; in fact, it is prudent to avoid hospitalization to minimize intra-hospital spread.

(3) Patients with severe and extensive inoculation vaccinia, progressive vaccinia and post-vaccinial encephalitis almost always require hospital care. In hospital, they must be isolated and care taken to separate all materials used in their care, treating such materials as infectious waste. For further information, please visit the Preventing Contact Transmission page.

Click on an adverse reaction image or topic

Immunity and Adverse Reactions
Immunity to vaccinia is dependent on both cell-mediated immune function and anti- body production. In general, individuals with intact cell-mediated immunity do not suffer serious consequences. Individuals with antibody-deficient states but with intact cell-mediated immunity generally handle vaccination without incident. However, there are reports of adverse events, even in this group of vaccinees.