"• The proportions of 21- to 30-year-olds who say they have ever shared needles in this way during their lifetime are 0.5% overall—0.6% of males and 0.4% of females (bottom of Table 4-1). As noted in the previous section, 1.5% of the full samples say they have ever injected a drug, so this indicates that a minority—but still a third (0.5%/1.5%)—of the people injecting any of the several drug classes mentioned in the question (heroin, cocaine, amphetamines, and/or steroids) shared a needle at some time.

"• The proportion of 21- to 30-year-olds who reported that they shared needles in the prior 12 months is 0.2%, with no significant gender difference. This compares to 0.5% who said that they have injected a drug in the prior 12 months, so about two fifths of past year injectors shared a needle at least once during the year.

"• Of respondents age 21-30, almost half of females who have injected in their lifetime reported having shared needles (0.4%/0.9%), compared to a little more than one-fourth of male injectors (0.6%/2.2%), suggesting that young adult female injectors are more at risk due to needle sharing. It seems likely that the rates are underestimates for the entire population in this age group due to the omission of high school dropouts, the likelihood that drug-addicted users would be more likely than average to leave the study, and the possibility of some underreporting of this behavior. But while the prevalence of needle sharing is low, it can still translate to sizable numbers of people engaging in shared needle use. An estimated 45 million Americans were between ages 20 and 29 in 2017 (US Census Bureau, 2018); just 0.5% of this group would be approximately 225,000 individuals.

"• To summarize, while young adult men are more likely to inject drugs than their female counterparts, they are only slightly more likely to share needles."


Johnston, L. D., O’Malley, P. M., Bachman, J. G., Schulenberg, J. E., Patrick, M. E., & Miech, R. A. (2019). HIV/AIDS: Risk & Protective Behaviors among Adults Ages 21 to 30 in the U.S., 2004–2018. Ann Arbor: Institute for Social Research, The University of Michigan.