The 'Swiss Statement' about the impact of antiretroviral
treatment on infectiousness appears to have had an impact on the sexual
behaviour of HIV-positive individuals in that country.
In the December 1st edition of Clinical Infectious Diseases investigators
report an association between taking HIV treatment that is reducing viral load
to undetectable levels and unprotected sex. The proportion of individuals
reporting sex without a condom with their main partner increased after January
2008 when senior Swiss doctors published their statement about the impact of
effective HIV treatment on infectiousness.
“In contrast to earlier results from our cohort, which did
not find an association between viral load and sexual behaviour, we now
observed an association of a suppressive ART [antiretroviral therapy] and
unprotected sexual contacts in MSM [men who have sex with men] and heterosexual
women with stable partners, indicating that some groups with HIV infection have
adopted the belief that treatment of HIV infection is a sufficient
HIV-prevention measure,” write the investigators.
An editorial that accompanies expresses some alarm about
individuals making decisions about the use of condoms on the basis of their
viral load. The author notes that infections have been attributed to patients
taking HIV therapy who have an undetectable viral load, and that the
understanding of the impact of HIV treatment on infectiousness is still
In January 2008 a group of senior HIV doctors in Switzerland
published what has become known as the Swiss
This said that HIV-positive heterosexuals could discontinue
condom use with their regular HIV-negative partner if:
- Their partner agreed.
- They were taking HIV treatment.
- Their blood viral load had been undetectable for
at least six months.
- They did not have any other sexually transmitted
Considerable controversy has surrounded the statement. There
is a general consensus that taking HIV treatment substantially reduces the risk
of sexual transmission of the virus. Nevertheless, many researchers believe
that a low risk of transmission persists.
Swiss investigators wanted to see if factors such as taking
HIV treatment, viral load, and drug and alcohol use were associated with
unprotected sex in their cohort of patients.
They therefore analysed self-reported condom use for 7309
patients between 2007 and 2009. The patients were divided according to their
HIV risk group: gay and other men who have sex with men; heterosexual men and
women; and injecting drug users.
Information was obtained on condom use with regular and
Investigators were also eager to see if the issuing of the
Swiss statement had lead to changes in reported condom use. Other
Swiss research has shown that about a quarter of gay men are using unreliable
HIV risk reduction strategies such as serosorting or strategic positioning.
The authors of this study noted that these risk-reduction methods have never
been promoted in Switzerland.
A total of 80% of patients were taking HIV treatment, and
82% of these individuals had an undetectable viral load.
Overall, sex with only one stable partner was reported by
46% of gay men, 80% of heterosexual men, 91% of heterosexual women, and 75% of
injecting drug users.
Having both a regular and casual partners was reported by
18% of gay men, 4% of heterosexual men, 1% of heterosexual women and 3% of
injecting drug users. In total, 37% of gay men said they only had casual
partners, as did 17% of heterosexual men, 8% of heterosexual women and 22% of
injecting drug users.
Regular condom use was reported by 89% of individuals with a
regular HIV-negative partner and by 48% of those whose partner was also
HIV-positive. In all four HIV risk groups, rates of consistent condom use were
lower with regular partners than casual partners (88 vs 92%, p < 0.001).
Factors associated with unprotected sex were:
- For all groups, time period after the release of
the Swiss Statement.
- An undetectable viral load for gay men (OR,
2.41; 95% CI, 1.35 to 4.30) and heterosexual women (OR, 2.73; 95% CI, 1.87 to 3.99)
with a stable partner.
- Younger age.
- Moderate to severe alcohol use for heterosexual
women and injecting drug users with stable partners and heterosexual men with
- Any illicit drug use for gay men and
heterosexual women with stable partners, and gay men, and heterosexual men and
women with casual partners.
The investigators focused on the impact of the Swiss
Statement on reported condom use with regular partners.
They found that even before the issuing of the statement,
there was already a progressive increase in the proportion of gay men and
heterosexual women reporting unprotected sex with their stable partner.
However, the release of the statement was followed by a decline in reported condom use by individuals with an undetectable
Gay men (OR, 2.81; 95% CI, 1.37 to 5.80), heterosexual men (OR,
1.58; 95% CI, 1.00 to 2.48) and heterosexual women (OR, 2.14; 95% CI, 1.43 to 3.22) whose
viral load was undetectable were all significantly more likely to say that they
had had unprotected sex with their main partner after the issuing of the
“The effect of the ‘Swiss Statement’ was most pronounced in
groups with stable partners who had an undetectable viral load,” comment the
investigators. They believe that their patients were able to accept the
“complex recommendations” of the statement.
The investigators also note that the release of the
statement and the subsequent change in sexual behaviour by their patients did not lead to an increase in observed new HIV infections in Switzerland.
They conclude that “because ART influences sexual behavior
in HIV serodifferent partners, adherence to treatment and plasma viral load
should be regularly monitored in the HIV-positive partner, and counselling of
couples should be advocated".
Such counselling should be individualised, and account
should be taken of drug and alcohol use.
Dr Myron Cohen, author of the editorial that accompanied the
study, said that there is “every reason to pause and reflect” about the actual
impact of HIV treatment on infectiousness. “The protection provided from ART is
not absolute and is not absolutely predictable,” he writes.
Cohen also notes that there are many unanswered questions
about the infectiousness of people taking suppressive HIV treatment. These
include the risk of transmission over time; the impact of different HIV
treatment combinations on infectiousness; and the risks involved with anal and
The author also notes that investigators “painstakingly”
defined their recommendations about the impact of HIV therapy and viral load on
the risk of mother-to-child transmission. He hopes that similar data will
direct the use of HIV treatment as prevention.