How long does a smallpox vaccination last?
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It's not clear how long a person's immunity to smallpox would last after they had been vaccinated. Protection against the virus is probably greatest for about three to five years. After that, the vaccine gradually becomes less effective, although a person could have partial immunity for a long time. A booster shot will provide longer immunity.
It's not clear how long a person's immunity to smallpox would last after they had been vaccinated. Protection against the virus is probably greatest for about three to five years. After that, the vaccine gradually becomes less effective, although a... More
