Illinois officials have introduced a voluntary smallpox vaccination program for residents exposed to the monkeypox virus in the past two weeks. As of Friday, there were five confirmed cases of monkeypox in Illinois as well as 12 probable ones. The Centers for Disease Control and Prevention reports that there have been 20 confirmed cases and 67 potential cases nationwide. Studies indicate that the smallpox vaccine can prevent monkeypox roughly 85 percent of the time, and as of June 19, 20 people across the country had received the smallpox vaccine for that purpose.