Vaccines for AIDS
News about a vaccine for Human Immunodeficiency Virus (HIV) was published in the front page of almost every newspaper, including The Jakarta Post and Kompas, in the past few days. For laymen, the message could be misconstrued as: stop worrying about the deadly and incurable threat of Acquired Immune Deficiency Syndrome (AIDS), very soon there will be vaccines to stop HIV, and AIDS will become just another disease like measles and smallpox.
This piece may be a rather pessimistic angle of the "good news," but it hopes to put the issue in the right prospective so that we are not misled by another fallacy on top of the many widespread myths about AIDS.
A vaccine usually makes use of a fragment of a virus, or the whole of dead virus. When a person is vaccinated, the immune system makes antibodies to fight the intruder. If and when the real virus arrives, the immune system is ready to destroy it.
No one wants to deliberately expose a vaccinated person to HIV because the vaccine may not work. So scientists draw blood from vaccinated volunteers, then mix antibodies from the blood with HIV made in the lab. With many HIV vaccines tested so far, the immune system seems to make ineffective, useless antibodies. Even if antibodies deactivate HIV in a test tube, it doesn't prove the vaccine will work in real life. Only by vaccinating large numbers of people and then keeping track of their health for years will scientists know how effective a given vaccine is. However, if the vaccine is tried only on people at high risk of getting AIDS, such as intravenous drug users, they might assume the shot automatically protects them when it may not. They may end up getting AIDS out of a false sense of security.
The HIV, the virus that causes AIDS, changes quickly in the human body. A single person may have several different versions of the virus in his or her body. HIV also varies from region to region in the world. At least nine subtypes exist: subtype B in the USA, C in western Indian, E in Thailand, and so on. A number of different HIV vaccines have to be developed, and people may be protected only from the HIV type in their own vaccine. This makes the challenge of developing and testing an effective vaccine more intriguing.
When scientists in a pharmaceutical company want to test a new vaccine on thousands of people, they must of course get permits from the government's Board of Health. The Board must decide whether the test is justified. If the new vaccine has only a 50 percent chance of being effective, they may decide that the risks outweigh the possible benefits. As a result, not many people are encourage to invest large sums of money in developing vaccines without assurance that the government will agree to test them. This is why it has taken so long for scientists to develop an effective vaccine. Recent reports that "we are almost there" are indeed good news, but we cannot rely 100 percent on it.
Even if a HIV vaccine is eventually found, it will most likely be very costly. The high costs of search and testing must be taken into account when determining the price. The best way is still prevention rather than cure. AIDS is actually more preventable than polio or measles were before the vaccines existed for those viruses. HIV is not passed on in everyday social settings. Perceptions that we can get AIDS through shaking hands, sharing towels and swimming pools are fallacies. In fact, 90 percent of HIV cases in the world were passed on through sexual intercourse. The best preventive methods are therefore: abstinence, or monogamy/being faithful to only one uninfected partner. If these two options do not work for you, consistent and correct use of latex condoms is the only other option. Having learned that HIV is such a mysterious killer, we cannot rely on a vaccine to keep us safe. We have to take responsibility for our own behavior.
ROBBY SUSATYO
Jakarta