On August 30th, The Proceedings of the National Academy of Sciences published an interesting study on monkeypox in DR Congo. The smallpox vaccine protects against monkeypox, but the eradication of smallpox means that children no longer are vaccinated against it (and are therefore susceptible to monkeypox). Rimoin et al report that cases of monkeypox have surged in recent decades. This study is not the first to identify an unexpected benefit of the smallpox vaccine. In a very preliminary study published earlier this year, Weinstein et al found immunologic evidence that the smallpox vaccine may provide some protection against HIV infection and progression.