Thunder is caused by the extremely rapid expansion of air around a bolt of lightning due to the very high temperature. It is also caused by the change of pressure around a lightning bolt.
Hope that helped you.
Answer:
"The smallpox vaccine does not contain smallpox virus and cannot spread or cause smallpox. However, the vaccine does contain another virus called vaccinia which is live in the vaccine. Because the virus is alive, it can spread to other parts of the body or to other people from the vaccine site."
[Copy and pasted from a medical website]
