In a study, published in The European Journal of Public Health with first author, Ellen J. Amundsen, it is shown that, when considered together, the different measures to prevent HIV-transmission in Scandinavia, a high level of HIV-testing and counselling render better results than legal and ready access to clean syringes and needles. This is the only study, so far, where these measures are evaluated comparatively.
Legal access to needles and syringes/ needle exchange programs versus HIV
counselling and testing to prevent transmission of HIV among intravenous drug
users: A comparative study of Denmark, Norway and Sweden.
Ellen J. Amundsen, Anne Eskild,
Hein Stigum, Else Smith, Odd O. Aalen
European Journal of Public Health Vol 13 (3): s.
252-258
You can read the abstract here and the full text article here if you subscribe to the online service of the
Journal.
You can read a Norwegian presentation of the study on SIRUS website here