July 12, 2006
New HIV infections stem from both people who are aware they are HIV-positive (about 75 percent of infected persons in the United States) and HIV-positive people who are unaware they carry the virus (about 25 percent of infected persons in the United States). In the current study, researchers estimated the two groups' relative roles in sexually transmitting new HIV infections to at-risk partners, those who are uninfected or whose serostatus is unknown, in the United States.
This estimation's parameters included: number of persons aware and unaware they are HIV-infected; 33 percent of the aware group are at low risk of transmitting the virus due to low/undetectable viral load; 57 percent relative reduction in unprotected anal and vaginal intercourse (UAV) with at-risk partners among persons aware they are infected, compared to those who are unaware; and assumed differences in the average number of at-risk UAV partners in each awareness group (a range from equal to twice as many in the unaware group).
The researchers estimated that the proportion of sexually transmitted HIV from the unaware HIV-positive group ranged from 0.54 (assuming no difference in the average number of at-risk UAV partners between groups) to 0.70 (assuming twice as many at-risk UAV partners in the unaware group). Applying the lower bounds and adjusting for population size differences between the groups, the transmission rate from the unaware group was 3.5 times that of the aware group.
"The results indicate that the HIV/AIDS epidemic can be lessened substantially by increasing the number of HIV-positive persons who are aware of their status," the researchers concluded.