How does condom use change over time as young MSM get older?

A longitudinal study using multiple cohorts of young men who have sex with men in Chicago aimed to investigate changes in condom use over time, from late adolescence to adulthood (aged 17-26), as well as historical patterns of change for cohorts of men recruited in different years. This research was carried out by Gregory Swann and colleagues at Northwestern University and is published in the May issue of The Archives of Sexual Behavior.

Researchers found that while men had more anal sex as they got older, there was a decrease in the proportion of that sex that was condomless. In terms of historical changes, of the three cohorts followed (recruited in 2007, 2010 and 2015), the 2015 cohort reported less condomless sex at age 17, but a higher growth in the proportion of sex that was condomless as they got older. This study is the first of its kind to indicate that cohorts recruited in more recent years may have different risk trajectories over time when compared to cohorts recruited previously.

Young men who have sex with men (MSM) have the highest HIV incidence in the US. Between 2001 and 2011, youth between the ages of 13 and 24 represented the fastest growing age group for new infections. In 2015, rates of new diagnoses stabilised for this age group but continued to increase among MSM aged 25-34, with a 23% increase from 2010 to 2015.



Having sex without condoms, which used to be called ‘unprotected’ or ‘unsafe’ sex. However, it is now recognised that PrEP and U=U are effective HIV prevention tools, without condoms being required. Nonethless, PrEP and U=U do not protect against other STIs. 

longitudinal study

A study in which information is collected on people over several weeks, months or years. People may be followed forward in time (a prospective study), or information may be collected on past events (a retrospective study).

risky behaviour

In HIV, refers to any behaviour or action that increases an individual’s probability of acquiring or transmitting HIV, such as having unprotected sex, having multiple partners or sharing drug injection equipment.

treatment as prevention (TasP)

A public health strategy involving the prompt provision of antiretroviral treatment in people with HIV in order to reduce their risk of transmitting the virus to others through sex.


Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).

“Given these high rates and trends, understanding how HIV risk changes from adolescence to young adulthood is especially important,” the authors say. “The goal of the present study was to observe how engagement in condomless anal sex changes over time from late adolescence to adulthood in young MSM. We also set out to assess whether cohorts of young MSM recruited in 2007, 2010, and 2015 differed in patterns of change in condomless anal sex from late adolescence to adulthood.”

In terms of historical changes, social factors, such as greater recognition of same-sex relationships and marriage equality, and biomedical developments, such as pre-exposure prophylaxis (PrEP) and treatment as prevention (TasP), may have had an impact. However, PrEP is only FDA-approved for those over 18 years of age and uptake has been low among young MSM, especially those of colour. Thus, condom use is still an important HIV prevention tool for this at-risk group.

Turning to changes as young men get older, previous longitudinal research on condom use has had varied findings. One study found that MSM who were younger at baseline were more likely to have higher increases of condomless sex over time; another found no significant changes over time in terms of condomless sex acts; and one reported that individuals were inconsistent over time in their sexual risk behaviour. However, these studies tended to follow men for less than two years and thus do not offer insight into change over longer periods of time.

The current study

Data came from RADAR: a longitudinal cohort study of HIV risk among young MSM in Chicago. Three cohorts of MSM between the ages of 16 and 20 were recruited in 2007 (N = 117), 2010 (N = 450) and 2015 (N = 589). The study is ongoing, with data collection occurring in waves (six to 18-month intervals) and the oldest participant is now aged 26. At each wave, participants provide demographic data and information on sexual acts with their three most recent sexual partners in the previous six months.

Average age at baseline was 19 years, while the average age at the most recent wave was 21. African Americans made up 38% of the entire sample, with 26% Latino, 25% White and 11% Asian/Pacific Islander, Native American or other. The majority (69%) identified as gay, 23% as bisexual and 8% as other.


A consistent pattern of developmental change was seen as young MSM made the transition from late adolescence to adulthood. Young MSM increased the average number of anal sex acts by approximately one additional act for each year of age, although this was not statistically significant. At the same time, the proportion of sex acts that were condomless decreased significantly, especially with casual partners.

On average, at age 17, young MSM had 10.2 anal sex acts and 57% of these were condomless (an average of 5.8 condomless sex acts). At 26, there was an average of 19.5 anal sex acts and 30% of these were condomless (an average of 5.9 condomless sex acts).

While the proportion of condomless acts decreased by nearly half, the absolute numbers of condomless acts were comparable. While younger men were engaging in less anal sex, acts were more likely to be condomless. However, as they aged, they were more likely to use condoms but were also having more sex and thus sexual risk did not necessarily decrease across development.

In terms of historical changes, the 2015 cohort reported a significantly lower proportion of condomless sex acts at age 17 but a significantly higher growth in condomless sex over time when compared to the 2010 cohort. The 2010 cohort averaged 5.8 condomless acts at age 17, 6.4 condomless acts at age 23 and 5.86 condomless acts at age 26. In comparison, the 2015 cohort averaged 3.24 condomless acts at age 17, increasing to an average of 8.71 condomless acts at age 23.

If this trajectory were to continue, they would average approximately 12 condomless acts at age 26. Thus, over time, the most recent cohort will be less likely to use condoms in comparison with earlier cohorts.


Consistent developmental change was seen over time, with an increase in the number of sexual acts and a decrease in condomless sex as the men aged. Historically, the findings for the 2015 cohort revealed that while they were more likely to use condoms at age 17, they were less likely to do so as they got older.

Results for cohorts recruited in earlier years suggest that they displayed less risky behaviour over time, especially when it came to casual partners. This may indicate the effects of focused prevention campaigns aimed at young MSM. The authors argue that the increase in risky behaviour in the more recent cohort might indicate a need for renewed prevention campaigns.

While these findings shed light on important differences between condom use in different cohorts, the researchers do not report on those who did start PrEP after the age of 18 in the different cohorts. Another important preventative aspect, even in the absence of condoms, is if an HIV-positive sexual partner is undetectable as there is no chance of infection in these instances. The researchers also did not report on how many men in these cohorts became infected with HIV.

Nonetheless, the authors make an important point and conclude by saying: “The continuation of the current pattern predicted in these models, if it occurs, could hint at even higher rates of infection for 25–34-year-old MSM than what currently occurs. Increased adoption of PrEP taken as directed could mitigate this potential future HIV risk, but not risk of other STIs.”


Swann G et al. Historical and Developmental Changes in Condom Use Among Young Men Who Have Sex with Men Using a Multiple-Cohort, Accelerated Longitudinal Design. Archives of Sexual Behavior 48: 1099-1110, 2019.