A preventive vaccine for rabies is given in three shots over 21 days. Preexposure vaccination does not eliminate the need for postexposure treatment, but postexposure treatment is simpler and shorter for those who have received a vaccine before exposure to rabies.

Booster shots should be considered when an occupation or hobby involves continued exposure to the virus. But the risk of allergic reaction to the vaccine increases with each dose, so a booster shot should be given only when the antibody level from the previous vaccine drops below an acceptable level. This is determined by a lab test that measures the level of rabies antibodies in the system. The test is performed every 6 months to 2 years, depending on risk.