The vaccine is essentially the same; the risk, however, is what's different. When I had the vaccine (back in the 60's), smallpox was still present. Now, it has been eradicated "in the wild", but still exists "in the laboratory". There certainly is a risk through bio-terrorism, and I don't discount that risk, but it is still low. The CDC states that the vaccine provides protection from infection for 3-5 years, and protection from severe illness and death for 10 or more years. Getting the vaccine within 3 days after exposure can prevent the disease or make it less severe; getting it within a week of exposure can still make the disease less severe. The info packet I received is available for free download at the CDC: http://www.bt.cdc.gov/agent/smallpox/vaccination/infopacket.asp . The images of vaccine reaction and of the disease itself are at http://www.bt.cdc.gov/agent/smallpox/smallpox-images/index.asp . Hope this helps.