Ask Doctor Neil Question: Are cold sores caused by the same
virus that causes colds? Cold sores are caused by the herpes
simplex virus, not by one of the over 200 viruses that leads to
colds. People infected with herpes simplex tend to have flare-
ups when their immunity is lowered such as during illness or
stress. Not infrequently, the herpes infection will cause a
mouth sore during or after a bad cold or flu hence the
association and the name. Question: Can I still get the flu if I
get the flu shot? Answer: In general the flu shot is 70-80%
effective; that is it provides complete protection 70-80% of the
time. As we get older, our response to the flu shot declines.
Over age 70, the flu shot maybe only 40% effective. Sometimes
people do not get the flu shot early enough in the year to
develop immunity before they are exposed to the virus. In other
situations, a case of flu may come from a virus not included in
the vaccine. When is a cold contagious? Answer: In children,
colds are contagious one to two days be