Injections seldom cause HIV infection.

Evidence indicates that sexual transmission--not unsafe injections--is the main way HIV spreads in sub-Saharan Africa, an international team has concluded.

In an article published in the February 2004 issue of The Lancet, the team reviewed and refuted assertions that unsafe injections given for medical reasons are a major mode of HIV transmission in the region. First, team members concluded that unsafe injections are not frequent enough to play a dominant role in such transmission. Transmission efficiency of HIV through injection in African health care settings is also far less than the 2.3 percent previously asserted, they estimated. This is, in part, because injections are usually intramuscular (rather than intravenous) and needles are likely to be cleaned before reuse.

Also, the team found that the asserted strong association between a history of injections and HIV infection did not adequately account for reverse causality. (Since HIV-infected individuals are more likely to be sick than are uninfected ones, they may be more likely to have received injections for treatment.) The asserted association also did not sufficiently account for confounding factors, particularly a history of sexually transmitted infections. The authors of the article also point out that there is no evidence that children receive fewer injections than do adolescents and adults, yet HIV infection (apart from mother-to-child transmission) is rare in children. Finally, the authors cite the HIV epidemic in South Africa, where unsafe injections are uncommon but HIV prevalence is very high: 26.5 percent in antenatal care clinics in 2002. On the other hand, substantial data indicate that unsafe sexual behaviors are the cause of the epidemic there.

In conclusion, the team found "no compelling evidence that unsafe injections are a dominant mode of HIV-1 transmission in sub-Saharan Africa. Conversely, though there is a clear need to eliminate all unsafe injections, epidemiological evidence indicates that sexual transmission continues to be by far the major mode of spread of HIV-1 in the region."