https://www.mercurynews.com/2022/08/16/does-decades-old-smallpox-vaccination-protect-against-monkeypox/

Health officials are scrambling to stretch scarce doses of vaccine to slow the mounting monkeypox outbreak, but do older people already vaccinated as kids for the related but deadlier smallpox virus already have protection?

The Centers for Disease Control and Prevention isn’t betting on it. The U.S. health agency says those exposed to the monkeypox virus “who have not received the smallpox vaccine within the last 3 years should consider getting vaccinated.” And on Monday, the CDC endorsed a strategy of giving the smallpox vaccine under the skin — at a fifth of the usual dose.