Scientific American, 7/98, Thomas J. Coates, Chris Collins, page 76
Preventing HIV Infection
Altering behavior is still the primary way to control the epidemic
With a vaccine still years away, the only broadly applicable way to prevent new HIV
infections is to change behaviors that enable transmission of those infections -
especially behaviors relating to sex and drug injection.
Because most people simply will not choose celibacy, realistic public health workers have focused on encouraging adoption of safer sexual practices, notably condom use. That people can be persuaded to employ safer sex is well illustrated by the experience of San Francisco's gay community in the 1980s. Perhaps 8,000 individuals became infected with HIV in both 1982 and 1983. That figure declined to 1,000 a decade later and is now estimated at less than 400 a year. The primary reason for this decline was a precipitous decrease in unprotected anal intercourse as a result of education about safer sex practices.
Targeted education aimed at a particular at-risk community is a prime way to persuade people to engage in preventive practices. In San Francisco, information about HIV transmission and safer
sex was made available in the media and at centers of gay society, such as churches, gay organizations and clubs. Programs aimed at the commercial sex industry have greatly lowered the risks of HIV transmission for both worker and client. In Thailand the Ministry of Public Health has attempted to inspire 100 percent condom use in brothels. It provides condoms and advocates safer sex practices through the media. From 1991 to 1995 the number of men who wore condoms when with prostitutes at brothels rose from 61 to 92.5 percent. HIV infection rates among Thai army conscripts fell from 12.5 percent in 1993 to 6.7 percent in 1995 because condom use was effective and also in part because fewer men employed prostitutes.
Testing and follow-up counseling reduce risk behaviors among both infected and uninfected individuals, as has been documented in a large study in three developing countries. A number of research efforts involving "discordant" heterosexual couples - where only one partner is HIV positive - have shown that counseling following a positive test
can strongly protect the uninfected partner. In Rwanda, condom use in discordant couples who received counseling increased from 3 to 57 percent. In Congo (the former Zaire), the increase was from 5 to 77 percent.
Comprehensive sex education in schools can promote safer sex while actually decreasing sexual activity among young people. A review of 23 school programs found that teens who received specific information and training about how to insist on condom use were less likely to engage in sex. Those who did have sex had it more safely and less frequently than those not exposed to AIDS-specific educational material. Adolescents not yet sexually active who receive information about HIV have their first sexual experiences later in life and have fewer sex partners than students who receive HIV information after they have begun having sex.
Peer influence and community action are excellent complements to more general education. In one investigation, researchers identified popular opinion leaders among gay men in small cities. The researchers trained these "trendsetters" to endorse safer sex practices among their friends and acquaintances. The number of men engaging in unprotected anal intercourse dropped by 25 percent in only two months; condom use went up 16 percent; and 18 percent fewer men had more than one sex partner. In two similar cities without such peer influences, no changes occurred. In another trendsetter study the rate of unprotected intercourse among young gay men fell by more than 50 percent. Such a drop in risk behavior could actually reduce the HIV transmission rate enough to stop the epidemic in that population.
Advertising and marketing can also change a community norm, making condoms more acceptable. A mass-media campaign advocating safer sex in Congo caused condom sales to increase from 800,000 in 1988 to more than 18 million by 1991. A local survey found that those claiming they practiced mutual fidelity went from 29 to 46 percent in a one-year period. An aggressive marketing campaign aimed at 17- to 30-yearolds in Switzerland saw condom use with casual sex partners rise from 8 to 50 percent between 1987 and 1991. Among 17- to 20-year-olds the figure went from 19 to 73 percent. Critics of the frank presentation of sexually oriented materials decry the potential for increasing rates of sexual activity. The Swiss study, however, found such rates to be unchanged-only the safety of the practices increased.
Easing access to condoms is another way to increase their use-both by giving them away and by making them less embarrassing to buy. A study published in 1997 in the American Journal o f Public Health reported that when condoms were made available in high schools, usage went up without an increase in number of sex partners or a lowering of the age of initiation of sexual activity. At a drug-abuse treatment center, condoms were almost five times as likely to be taken from private rest rooms as from a public waiting area. Clearly, the perception of privacy encourages the acquisition of condoms.
Physician-patient dialogue may also help reduce risk behaviors, but doctors have squandered valuable opportunities. A recent study found that only 39 percent of adolescents ever talked with their doctors about avoiding HIV, and only 15 percent discussed their sex lives; however, almost 75 percent said they would trust their doctors with information about their sex habits, and up to 90 percent said they would find it helpful to talk about sex with a doctor Ninetyfour percent of physicians ask about smoking habits; frank discussions of sex are no less appropriate in a doctor-patient setting.
Drug treatment should be a first-line approach to reducing risk for HIV and other infectious diseases in intravenous drug users. Substitution strategies, such as methadone treatment for heroin addiction, clearly reduce transmission of HIV through needle sharing.
Access to clean needles can help protect those still using injection drugs. Exchange programs, despite the controversies they elicit, have been shown to lower the risk of viral infection in many studies worldwide. Six U.S. government-funded studies have found that needle exchanges help to reduce HIV transmission without leading to greater drug use. Some jurisdictions have expanded beyond needle exchange. In 1992 Connecticut began a model program in which pharmacists were permitted to sell and individuals were allowed to possess up to 10 syringes without medical prescriptions. Among users who reported ever sharing syringes, sharing dropped from 52 to 31 percent, and street purchases of syringes dropped from 74 to 28 percent. Fears of encouraging drug abuse have proved unfounded: many studies have shown that needle availability does not increase the use of illegal drugs.
Direct outreach to drug users is also effective. A program supported by the National Institute on Drug Abuse followed 641 injection addicts, consistently encouraging them to seek treatment to get off drugs and use safe injection methods in the interim. After four years, 90 individuals had contracted HIV, only half the statistical expectation for that population.
What Does Not Work
One-time exposure to information is less successful than interventions that teach skills and reinforce positive behaviors repeatedly. Young people in particular need to learn exactly how to use condoms and how to be assertive about demanding their use before they will modify their behavior significantly.
A single message is insufficient to reach the multiple diverse communities grappling with the AIDS epidemic. Educational approaches must be tailored to fit the ethnicity, culture and sexual preference of a given population. The San Francisco example of outreach aimed at the gay community attests to the success of this focused approach.
Abstinence-only programs do a disservice to America's youth. Congress recently approved $250 million for five years of sex education restricted to discussions of abstinence alone. Such efforts cater to a political agenda more than any societal realities-two thirds of high school seniors say they have had intercourse. Educational programs, while encouraging abstinence, must provide the knowledge and means to protect the young from HIV
Coercive measures to identify people with HIV or their sexual partners are likely to backfire. In this age of promising HIV therapies, it is important that infected individuals enter care as soon as possible after diagnosis. Early therapy can also prevent pregnant mothers from passing HIV to their children. But mandatory testing and the threat of coercive measures to identify sexual contacts undermine faith in and comfort with the health care system. A 1995 survey in Los Angeles found that 86 percent of those responding would have avoided an HIV test if they knew their names would be given to a government agency. Expanding opportunities for anonymous and confidential testing can bring more people into care and counseling.
Settling for the status quo is also a threat to prevention. Investigators need to continue to develop and refine interventions that can reach groups at risk. Women in particular need approaches that protect them from infected partners. With access to female condoms, their rates of sexually transmitted diseases are lower than when only male condoms are available. Better microbicides would likewise protect women whose partners are unwilling to practice safer sex.
Prevention is in many ways a less exciting topic than the development of wonder treatments or a vaccine. Yet effective behavioral and policy interventions are the best tools available to address an epidemic in which 16,000 people become infected worldwide every day. Concerted research on HIV vaccines must continue. Yet even when a vaccine is available, it most likely will not confer 100 percent protection on all those vaccinated. Distribution of the vaccine to everyone in need is another obstacle on the road to full protection.
Therefore, behavioral intervention will continue to play a role in bringing the global HIV epidemic under control and is indeed a matter of life and death. As June Osborn, former chair of the National Commission on AIDS, has said, "If we do preventive medicine and public health right, then nothing happens and it is very boring. We should all be praying for boredom."