Use of Antiretroviral Drugs for Prevention of New Infections with HIV

Every year 2.5 million individuals become newly infected with HIV. This
highlights that current ways for prevention of transmission, such as use
of condoms, are not sufficient to limit the spread of HIV infection.
Novel prevention strategies using antiretroviral drugs are being
developed. One of these strategies is pre-exposure prophylaxis (PrEP)
with antiretroviral drugs. The effect of drug resistance will be a
critical issue in the use of PrEP. Drug resistance will reduce the
effectiveness of PrEP. This detrimental effect could be counterbalanced
by the reduced fitness of drug-resistant HIV, which may result in lower
levels of virus particles. Because the amount of virus is a major
determinant of the risk of transmission, drug-resistant HIV could be
transmitted less easily. During the seminar I will discuss that the
benefits of PrEP are expected to outweigh the risks associated with drug
resistance (1.2). Another prevention strategy is “test and treat” in
which testing positive for HIV is followed by treatment. HIV-testing can
prevent new infections as individuals aware of their HIV-status can
reduce their risk behaviour. Treatment of infected individuals can
prevent new infections, as antiretroviral drugs can suppress the amount
of virus to undetectable levels. Mathematical modelling has predicted
that universal HIV testing followed by immediate start of antiretroviral
drugs for those individuals who test positive, could reduce the HIV
pandemic to one incident case of HIV per 1000 people within a decade
(3). But, universal testing and immediate treatment may not be achieved
in clinical practice in Africa (4) where most new infections occur
World-wide. We used realistic data from a rural hospital in Macha in
Zambia and used assumptions about testing and treatment that can be
achieved in clinical practice. Using mathematical modelling we found
that “test and treat” can strongly reduce the incidence of HIV but
cannot eliminate the epidemic. “Test and treat” will lead to an
increased prevalence of HIV as infected individuals will live longer.