  We have learned to live with many potentially deadly viruses for which there
is no vaccine, no immunity, and no cure. We do not live in constant fear of
these viruses, instead, we have learned how to outsmart them and reduce the
harm they cause. A new mathematical model that combines the spread of diseases
that do not confer immunity together with the evolution of human behaviors
indicates that we may be able to fight new diseases with the same type of
strategy we use to fight viruses like HIV.
