How can HIV transmission be prevented?
HIV can be transmitted in three main ways:
- Sexual transmission
- Transmission through blood
- Mother-to-child transmission
Wherever there is HIV, all three routes of transmission
will take place. However the number of infections resulting from each route will vary greatly between countries and population
For each route of transmission there are things that
an individual can do to reduce or eliminate risk. There are also interventions that have been proven to work at the community,
local and national level.
To be successful, an HIV prevention programme must
make use of all approaches known to be effective, rather than just implementing one or a few select actions in isolation.
Although most of this page looks separately at each
transmission route, it should be remembered that many people don’t fit into only one “risk category”. For
example, injecting drug users need access to condoms and safer sex counselling as well as help to reduce the risk of transmission
There are three key things that can be done to help
prevent all forms of HIV transmission. First among these is promoting widespread awareness of HIV and how it can be spread.
Media campaigns and education in schools are among the best ways to do this.
Another essential part of a prevention programme is
HIV counselling and testing. People living with HIV are less likely to transmit the virus to others if they know they are
infected and if they have received counselling about safer behaviour. In particular, a pregnant woman who has HIV will not
be able to benefit from interventions to protect her child unless her infection is diagnosed. Those who discover they are
uninfected can also benefit, by receiving counselling about how to remain that way.1, 2
The third key factor is providing antiretroviral treatment. This treatment enables people living with HIV to enjoy longer, healthier lives,
and as such it acts as an incentive for people to volunteer for HIV testing. It also brings people into contact with health
care workers who can deliver prevention messages and interventions. However, it is important that people understand the limitations
of the treatment, and that reduced fear of HIV doesn’t lead to more risky behaviour.3
Someone can eliminate or reduce their risk of becoming
infected with HIV during sex by choosing to:
- Abstain from sex or delay first sex
- Be faithful to one partner or have fewer partners
- Condomise, which means using male or female
condoms consistently and correctly
There are a number of effective ways to encourage
people to adopt safer sexual behaviour, including media campaigns, social marketing, peer education and small group counselling.
These activities should be carefully tailored to the needs and circumstances of the people they intend to help. Specific programmes
should target key groups such as young people, women, men who have sex with men, injecting drug users and sex workers.4,
Comprehensive sex education for young people is an
essential part of HIV prevention. This should include training in life skills such as negotiating healthy sexual relationships,
as well as accurate and explicit information about how to practise safer sex. Studies have shown that this kind of comprehensive
sex education is more effective at preventing sexually transmitted infections than education that focuses solely on teaching
abstinence until marriage.7, 8
Numerous studies have shown that condoms, if used
consistently and correctly, are highly effective at preventing HIV infection.9 Also there is no evidence that promoting
condoms leads to increased sexual activity among young people. Therefore condoms should be made readily and consistently available
to all those who need them.10
Another significant intervention is providing treatment
for sexually transmitted infections, such as chlamydia and gonorrhoea. This is because such infections, if left untreated,
have been found to facilitate HIV transmission during sex.11, 12
A number of studies have found male circumcision to
be associated with a lower rate of HIV infection. However, it is not yet clear to what extent this is an effect of circumcision
itself, or whether other factors may also play a role, and the World Health Organisation has yet to recommend circumcision
for HIV prevention. Further research on this issue is ongoing.13, 14
One group that shouldn’t be overlooked by HIV
prevention programmes is those who are already living with the virus. Regular counselling can help HIV positive people to
sustain safer sexual behaviour, and so avoid onward transmission.15, 16
What are the obstacles?
It is usually not easy for people to sustain changes
in sexual behaviour. In particular, young people often have difficulty remaining abstinent, and women in male-dominated societies
are frequently unable to negotiate condom use, let alone abstinence. Many couples are compelled to have unprotected sex in
order to have children.
Some societies find it difficult to discuss sex openly,
and some authorities restrict what subjects can be discussed in the classroom, or in public information campaigns, for moral
or religious reasons. Particularly contentious issues include premarital sex, condom use and homosexuality, the last of which
is illegal or taboo in much of the world.
Marginalisation of groups at high risk, such as sex
workers and men who have sex with men, can be another hindrance to HIV prevention efforts.
AVERT.org has more about preventing sexual transmission of HIV.
Transmission through blood
People who share equipment to inject recreational
drugs risk becoming infected with HIV from other drug users. Methadone maintenance and other drug treatment programmes are
effective ways to help people eliminate this risk by giving up injected drugs altogether. However, there will always be some
injecting drug users who are unwilling or unable to end their habit, and these people should be encouraged to minimise the
risk of infection by not sharing equipment.17
Needle exchange programmes have been shown to reduce
the number of new HIV infections without encouraging drug use. These programmes distribute clean needles and safely dispose
of used ones, and also offer related services such as referrals to drug treatment centres and HIV counselling and testing.
Needle exchanges are a necessary part of HIV prevention in any community that contains injecting drug users.18
Also important for injecting drug users are community
outreach, small group counselling and other activities that encourage safer behaviour and access to available prevention options.19
Transfusion of infected blood or blood products is
the most efficient of all ways to transmit HIV. However, the chances of this happening can be greatly reduced by screening
all blood supplies for the virus, and by heat-treating blood products where possible. In addition, because screening is not
quite 100% accurate, it is sensible to place some restrictions on who is eligible to donate, provided that these are justified
by epidemiological evidence, and don’t unnecessarily limit supply or fuel prejudice. Reducing the number of unnecessary
transfusions also helps to minimise risk.20, 21
The safety of medical procedures and other activities
that involve contact with blood, such as tattooing and circumcision, can be improved by routinely sterilising equipment. An
even better option is to dispose of equipment after each use, and this is highly recommended if at all possible.
Health care workers themselves run a risk of HIV infection
through contact with infected blood. The most effective way for staff to limit this risk is to practise universal precautions,
which means acting as though every patient is potentially infected. Universal precautions include washing hands and using
protective barriers for direct contact with blood and other body fluids.22
What are the obstacles?
Despite the evidence that they do not encourage drug
use, some authorities still refuse to support needle exchanges and other programmes to help injecting drug users. Restrictions
on pharmacies selling syringes without prescriptions, and on possession of drug paraphernalia, can also hamper HIV prevention
programmes by making it harder for drug users to avoid sharing equipment.
Many resource-poor countries lack facilities for rigorously
screening blood supplies. In addition a lot of countries have difficulty recruiting enough donors, and so have to resort to
importing blood or paying their citizens to donate, which is not the best way to ensure safety.
In much of the world the safety of medical procedures
in general is compromised by lack of resources, and this may put both patients and staff at greater risk of HIV infection.
AVERT.org has more about preventing HIV transmission among
injecting drug users and in health care settings.
HIV can be transmitted from a mother to her baby during
pregnancy, labour and delivery, and later through breastfeeding. The first step towards reducing the number of babies infected
in this way is to prevent HIV infection in women, and to prevent unwanted pregnancies.
There are a number of things that can be done to help
a pregnant woman with HIV to avoid passing her infection to her child. A course of antiretroviral drugs given to her during
pregnancy and labour as well as to her newborn baby can greatly reduce the chances of the child becoming infected. Although
the most effective treatment involves a combination of drugs taken over a long period, even a single dose of treatment can
cut the transmission rate by half.23
A caesarean section is an operation to deliver a baby
through its mother’s abdominal wall, which reduces the baby’s exposure to its mother’s body fluids. This
procedure lowers the risk of HIV transmission, but is likely to be recommended only if the mother has a high level of HIV
in her blood, and if the benefit to her baby outweighs the risk of the intervention.24, 25
Weighing risks against benefits is also critical when
selecting the best feeding option. The World Health Organisation advises mothers with HIV not to breastfeed whenever the use
of breast milk substitutes (formula) is acceptable, feasible, affordable, sustainable and safe. However, if safe water is
not available then the risk of life-threatening conditions from formula feeding may be higher than the risk from breastfeeding.
An HIV positive mother should be counselled on the risks and benefits of different infant feeding options and should be helped
to select the most suitable option for her situation.26
What are the obstacles?
In much of the world a lack of drugs and medical facilities
limits what can be done to prevent mother-to-child transmission of HIV. Antiretroviral drugs are not widely available in many
resource-poor countries, caesarean section is often impractical, and many women lack the resources needed to avoid breastfeeding
HIV-related stigma is another obstacle to preventing
mother-to-child transmission. Some women are afraid to attend clinics that distribute antiretroviral drugs, or to feed their
babies on formula, in case by doing so they reveal their HIV status.
AVERT.org has more about preventing mother-to-child transmission and HIV in pregnancy.
To be successful, a comprehensive HIV prevention programme
needs strong political leadership. This means politicians and leaders in all sectors must speak out openly about AIDS and
not shy away from difficult issues like sex, sexuality and drug use.
response also requires strategic planning based on good quality science and surveillance, as well as consideration of local
society and culture. All sectors of the population should be actively involved in the response, including employers, religious
groups, non-governmental organisations and HIV-positive people. Many of the world's most successful HIV prevention efforts
have been led by the affected communities themselves.
HIV epidemics thrive on stigma and discrimination related to people living with the virus and to marginalised groups such as sex
workers. Their spread is also fuelled by gender inequality, which restricts what women can do to protect themselves from infection.
Protecting and promoting human rights should be an essential part of any comprehensive HIV prevention strategy. This includes
legislating against the many forms of stigma and discrimination that increase vulnerability.