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."