Medicines and vaccines are used to prevent infections and certain diseases (opportunistic infections) that are more common in people with HIV.

• Primary prevention means preventing illness before it occurs. Immunizations (vaccines) are one kind of primary prevention. Medicines that kill or control the organisms that cause infections are another type of primary prevention.
• Secondary prevention means preventing a disease that a person has already had from coming back. This is usually done with medicines that slow or prevent the growth of the organisms that cause infections.

Generally, infection with HIV does not make people sick, except for the flu-like illness that may develop shortly after they become infected. Most people who are infected with HIV get sick because their immune systems become weak and cannot fight off other infections. So, preventing opportunistic infections is an important part of treatment for HIV.

If you have been diagnosed with HIV infection, make sure that you and your partner are up to date on the following immunizations:

• Pneumococcal vaccine. If it has been more than 5 years since you received your first dose of this vaccine, you may need a booster shot.
• Hepatitis A vaccine, given in a series of 2 shots.
• Hepatitis B vaccine, given in a series of 3 shots.
• Combination hepatitis A and hepatitis B vaccine, given in a series of 3 shots.
• Influenza vaccine (flu shot), given yearly.
• Other vaccines such as tetanus.

The list of medicines used to prevent opportunistic infections is too long to present in this topic. Work with your health professionals to decide which medicines to use, based on:

• The type of infection that is present or likely to develop.
• Which other medicines you are already taking and the possibility that one medicine might make another less effective (negative interaction).
• The side effects of the medicines.