Doesn vaccination within 4 days of exposure to smallpox prevent smallpox?
No. Although some people vaccinated after smallpox exposure will escape getting smallpox (as will some people who are not vaccinated), most people vaccinated after smallpox exposure will still get smallpox, although they are very likely to get a milder case and are much less likely to die from smallpox. Persons exposed to smallpox will have to be quarantined or be subject to personal surveillance for the time they may develop smallpox, despite being vaccinated. Persons exposed to smallpox who are vaccinated, but do not have a take, will likely get an unmitigated case of smallpox. Therefore, a response plan that involves vaccination only after exposure will not prevent smallpox, will not avoid the need to quarantine the exposed (and therefore restrict their work and contacts), and, in the small proportion of people who do not have a successful vaccination, will lead to severe and life-threatening disease. On the other hand, there has never been a case of smallpox reported in a smallpox
