Question: Can you catch AIDS by tongue kissing?
One-line questions such as this, scribbled on a scrap of paper, indicate to me that the public education about AIDS still has a long way to go!
NO. You cannot catch AIDS from kissing—no matter how passionate. AIDS cannot be caught by any form of casual encounter. It cannot be caught 1 shaking hands, by a cough or sneeze, by dirty toilets or by spa baths. It theoretically possible, although unlikely, to catch AIDS from oral sex.
Normal intercourse and anal sex, as well as any method of transfer of contaminated blood products from one person to another (eg. a shared needle) are the only methods of AIDS transmission. Injections given by doctors or dentists are given using needles that are used once only. Even ear piercing is done by the use of stud guns that cannot transmit AIDS.
AIDS is quite a difficult disease to catch, but if you are promiscuous in your sexual habits, or are involved with illegal drugs, your chances increase dramatically. Condoms offer some protection against AIDS, but not 100% protection because they can burst of come off at the wrong time.

Question: How can AIDS be prevented? Is there a vaccine you can have?
Scientists from around the world have been working overtime in their laboratories for the past two decades since AIDS first appeared in order to develop a long-lasting AIDS vaccine. The scientists who succeed will not only save millions of lives, but almost certainly will win a Nobel Prize.
So far no vaccine has been developed that can be proved to work. Numerous experimental vaccines have been tried on monkeys (who can get a mild form of AIDS) and human volunteers, but without success. It is probable that one will be developed in the future, but the AIDS virus is a different type to most viruses, and no vaccine against any virus of this type has yet been developed.
AIDS can be prevented almost completely (but not totally) by using condoms when you have any sort of penetrative sex, and not sharing needles if you are an injecting drug user. The best form of protection is a long term relationship with a single sexual partner.