While the smallpox vaccine worked wonders by eradicating a deadly disease, it may have uses in future medicine. A recent study has emerged in which patients with liver cancer received live attenuated Vaccinia virus [smallpox vaccine].
Vaccinia has been found to preferentially infect cancer cells because their production of antiviral interferon has been turned off signals that attract Vaccinia have been turned on.
More research has to be done to determine the causality of the Vaccinia virus on patient health outcomes but from this preliminary study, patients who received vaccine survived for longer than patients who did not.
More can be read at: http://www.newscientist.com/article/dn21158-smallpox-vaccine-doubles-liver-cancer-survival-time.html