1 in 3 young adults are susceptible to severe COVID-19 symptoms — here’s why

It’s been agreed upon by health officials for months now that older adults and individuals with preexisting health conditions are considered the most at-risk group when it comes to COVID-19. But, as coronavirus numbers continue to rise all over the United States, more and more young people are contracting the virus.

Now, the University of California, San Francisco has released a sobering new study suggesting that young adults aren’t nearly as impervious to COVID-19 symptoms as many have believed up until this point. After analyzing a nationally representative dataset including 8,405 U.S. men and women between the ages of 18 and 25, the team at UCSF concluded that the overall population “medical vulnerability” for severe COVID-19 symptoms is 33% for American males and 30% for American females within that age group.

Those percentages equate to about one in every three young adults being particularly susceptible to the development of severe COVID-19 symptoms in the event of an infection.

So, why are some young Americans more vulnerable than others? According to the study’s authors, one risk factor stood above the rest: smoking habits. While young adults may feel like they don’t have to personally worry about the coronavirus, this study indicates that isn’t the case for regular smokers.

“Recent evidence indicates that smoking is associated with a higher likelihood of COVID-19 progression, including increased illness severity, ICU admission or death,” says first study author Sally Adams, Ph.D., of the UCSF Division of Adolescent and Young Adult Medicine, in a university release. “Smoking may have significant effects on young adults, who typically have low rates for most chronic diseases.”

Researchers measured vulnerability by looking for established COVID-19 risk factors, as described by the CDC, among studied Americans. Such factors included various ailments (heart problems, asthma, diabetes, immune conditions), obesity, and tobacco intake (cigarettes, cigars, e-cigarettes) over the previous 30 days.

A fairly simple approach to the data was chosen by researchers. Instead of attempting to construct a cumulative vulnerability estimate based on all risk factors, the presence of just one was enough for an individual to be deemed “vulnerable.” For example, a healthy 20-year old man with no nagging health conditions would be considered vulnerable to severe COVID-19 symptoms if he was a habitual cigarette smoker.

When all smokers were removed from the dataset, leaving 6,741 non-smoking Americans remaining, that group’s coronavirus vulnerability was estimated to be 16.1%. Once smokers were added into the equation, however, the full dataset’s vulnerability score increased significantly to 31.5%.

“The risk of being medically vulnerable to severe disease is halved when smokers are removed from the sample,” explains senior study author Charles Irwin Jr., MD, of the UCSF Division of Adolescent and Young Adult Medicine. “Efforts to reduce smoking and e-cigarette use among young adults would likely lower their vulnerability to severe disease.”

Smoking isn’t nearly as popular as it was decades ago, but a lot of young people still indulge in the habit. There were more smokers among the examined group (19.8%) of Americans than people diagnosed with asthma (8.6 %), obesity (3%), and immune system issues (2.4%). Also, far more male participants reported smoking than females, which explains why men have a higher vulnerability score.

U.S. hospitalization rates for young adults are also on the rise. In the middle of April, there were only 8.7 young adults hospitalized per 100,000 people in that age group (18-29 years old). By the end of June, that figure had increased to 34.7 hospitalizations per 100,000 young adults. That’s a 299% increase.

The full study can be found here, published in the Journal of Adolescent Health.