Some RNA viruses are vaccine preventable. Common RNA viruses include HIV, hepatitis C virus, encephalitis B virus, influenza virus, rhinovirus, poliovirus, rotavirus, SARS virus, MERS virus, Ebola virus, and the recent new coronavirus. Polio, enterovirus, hepatitis A virus, HIV, and influenza viruses are currently available with preventive vaccines that work well to control epidemics. But in general, because RNA viruses are prone to mutation and mutate rapidly, the development of vaccines for RNA viruses is very difficult, and even if a vaccine for RNA viruses is developed one day, it is possible that new mutated viruses may still appear every year, and new vaccines need to be developed continuously.