Question: Given that so many young people (< 35) are coming down with positive tests, and are notoriously being careless about risk-taking and making everyone vulnerable, how can we impress upon them to abide by appropriate protocols? The youthful invincible attitude cannot work for COVID spread!

Answer: There has been a lot of media coverage of younger people taking risks. Honestly, I’m afraid it’s a bit unfair to younger people. Let’s look into the issue more deeply.

Are we seeing more cases among younger people? Yes, we are seeing more cases among people ages 18–49. As Figure 1 shows, we are seeing far more tests among young people (yellow bar) and an increasing proportion of tests coming back positive over the last 3 weeks (yellow line). More tests and increasing proportion of tests being positive== more cases. [Note: CDC’s data on age groups lumps ages a bit awkwardly, hence the 18–49, 50–64 distinction I’m using for this post]

Is the proportion of cases skewing more youthful over time? Yes. We are seeing an increasing proportion of positive cases among people ages 18–49 as compared with people ages 50–64. Analyzing CDC data, we see that the proportion of positive cases among people ages 18–49 compared with those 50–64 has steadily increased over the last 12 weeks — from 1.2 cases to 1 in early April to 3.7 cases to 1 in late June (data not shown). This has accompanied an increase in testing among people ages 18–49 compared with those ages 50–64–1.8 tests to 1 in early April to 2.4 tests to 1 in late June (data not shown). As these data reveal, the increase in the proportion of cases among those ages 18–49 is steeper than the increase in the proportion of tests. The proportion of cases is increasingly skewing more youthful.

Do we know why we are seeing more cases among younger people? More cases could be due to at least four factors: 1) more tests; 2) young people facing more exposure as they are more engaged in the workforce; 3) older people increasingly avoiding unnecessary risk; 4) younger people increasingly taking unnecessary risk. We know that earlier in the epidemic those with mild/moderate symptoms were asked to stay home and many of them did not receive tests. As testing has expanded, younger people are increasingly able to test. That said, the fact that the proportion of tests coming back positive has been increasing over the last several weeks means that more testing is not the full reason for more cases. When it comes to the other three factors, we just don’t have enough data to know to what degree each of these factors is influencing the changing demographics of the epidemic in the United States. We do know that younger people are more likely to have lower paying jobs, more likely to be in riskier, essential-worker-type jobs — health care, meat-packing plants, grocery stores, and factories — and less like to have sick time off compared with older people.

How do we talk about risk? Social behavior change is of utmost importance! People need education, but education is not sufficient. And in the context of ongoing risk, we have to use harm reduction strategies, which means helping people navigate risk rather than telling people to simply avoid it — very few people can hole up at home for the long-term, and this is especially true for younger people. Figure 2 presents a helpful infographic on social behavior change from a recent article published in Nature. This paper gives a great primer on social behavior change. Meanwhile, the Johns Hopkins Center for Communication Programs is leading the COVID Communications Network to help professionals with messaging, including risk communication.

Figure 1. Trends in COVID Tests and Test Positivity Rates by Age Group (from CDC, updated July 3rd)

Figure 2. Social Behavior Change Issues (from Nature)