Treatment as Prevention – A Three Part Series

Part One – HIV Treatment Debate Rages

An Introduction to the Controversial Swiss Study

Following a review of recent medical research, the Swiss Federal Commission for HIV/AIDS issued a highly controversial statement in their Bulletin of Swiss Medicine. The Swiss study stated that “an HIV-infected person on antiretroviral therapy with completely suppressed viraemia (“effective ART”) is not sexually infectious, i.e. cannot transmit HIV through sexual contact.”1

According to the Commission, this is true so long as the following requirements are met:2

• the person adheres to antiretroviral therapy (and the effects of this are monitored regularly by the treating physician)
• the viral load has been suppressed to an “undetectable level” (less than 40 copies/ml) for at least six months
  
• the person does not have any sexually transmitted infections
• the person is in a “stable relationship”
  

The findings of the Commission are significant and hotly debated, as they imply that HIV positive people can have unprotected sex with HIV negative partners without risk of transmitting HIV.

Since the Commission issued this statement, their conclusions have come under considerable scrutiny by UNAIDS, WHO, Public Health Agency of Canada and AIDS Service Organizations such as AIDS Calgary. Criticisms have centred both on the scientific accuracy of their argument and the real world applicability of their statement. Some key areas of concern are:3

• People are not always adherent to their medication regime, particularly in the face of severe side effects or other life challenges, and this can cause their viral loads to increase suddenly and significantly. Even those who do adhere to treatment can develop resistance to their drug regime or simply have “blips” in their viral load. In addition, the frequency with which people actually visit the doctor for viral load testing combined with the waiting period to receive test results makes it extremely difficult for someone to accurately know their viral load levels.

• Although the Commission argues that antiretroviral therapy eliminates HIV from genital secretions, this statement has been challenged. Critics point out that with only 2% of the body’s immune cells carried in the blood, blood may not accurately reflect viral load levels in other parts of the body (98% of immune cells are found in the lymph nodes and lymph tissues that line the gastrointestinal tract).

• It is common for people to have sexually transmitted infections without experiencing any symptoms; therefore it is difficult for people to know whether they have an STI at any given time.

• While some people maintain long term monogamous relationships, others do not, and people may be unaware of whether their relationships are monogamous due to the undisclosed affairs of their partners. The Commission’s statement is also based solely on data from studies of heterosexual couples, so the applicability of their statement to relationships between men is unclear.

While it may be true that adherence to treatment reduces viral load and that undetectable viral load correlates with a reduced likelihood of HIV transmission, when placed in real world conditions, the feasibility of the Commission’s statement comes under significant fire.

Next Week: Part 2 of Treatment as Prevention explores the community response to the Swiss study.

1 Bernard, Edwin J. (2008). Swiss experts say individuals with undetectable viral load and no STI cannot transmit HIV during sex. http://www.aidsmap.com/en/news/4E9D555B-18FB-4D56-B912-2C28AFCCD36B.asp%20%20Retrieved%20November%202008

2 Bernard, Edwin J. (2008). Swiss experts say individuals with undetectable viral load and no STI cannot transmit HIV during sex. http://www.aidsmap.com/en/news/4E9D555B-18FB-4D56-B912-2C28AFCCD36B.asp Retrieved November 2008; Canadian AIDS Treatment Information Exchange (2008). Swiss guidelines take a troubling turn. http://www.catie.ca/catienews.nsf/news/A2EFD4077BD44FB285257405005EE5EF?OpenDocument%20%20Retrieved%20November%202008.

3 Canadian AIDS Treatment Information Exchange (2008). Swiss guidelines take a troubling turn. http://www.catie.ca/catienews.nsf/news/A2EFD4077BD44FB285257405005EE5EF?OpenDocument%20%20Retrieved%20November%202008