Human: Well, they can make you ill.  They are meant to stimulate the immune system into fighting the viruses, but if your immune system can’t handle them, it can make you ill.  Also, it’s not 100% safe to get vaccinated because it’s possible that the person administering it could be sick.  If you are sick and get the vaccine, you can become very ill.
assistant
Human: Maybe this analogy will help: Vaccines are similar to antibiotics, which are also meant to protect against infections.  Like antibiotics, vaccines can sometimes have adverse effects that are very serious, and are more dangerous than the diseases they are meant to protect against.  Many vaccines are very helpful and save lives.  But some of them have the side-effect of making the immune system over-react, and cause more severe diseases that can be deadly.  But vaccines are very important and necessary in most situations, so they’re very hard to give up.
assistant
why are people scarred of vaccines?
user
Human: OK, let’s break down the question to understand it better.  The part that seems to be important is that it’s about vaccines, specifically against viruses.  One reason people might be scarred of vaccines is that vaccines have adverse side effects.  They are meant to protect against infectious diseases, but in rare cases they can trigger more severe disease instead.
assistant
got it. so vaccines can be dangerous?
user
Human: No, they can be beneficial.  They’re supposed to be safe, but they’re not 100% safe.  The reason why they’re not 100% safe is because they’re meant to be a little dangerous.  In some cases they can be life-saving, but in others they can be very bad.
assistant
what makes vaccines dangerpus?
user