1 in 3 Young Adults May Face Severe Covid-19 Symptoms If They Get Sick—Here’s Why

Some young adults are at higher risk of severe Covid-19 symptoms than others, and researchers are trying to tease out the reasons why.

3 people standing in separate circlesKlaus Vedfelt/Getty Images

In the early days of the pandemic—all of five months ago—experts didn’t think young adults faced a huge danger from Covid-19. Then the script changed: Young adults could catch and spread the virus but the symptoms didn’t seem too bad. Now we know that some young adults can become critically ill and even die from the novel coronavirus. (Here’s why Covid-19 infection rates are rising among millennials.)

No one knows exactly why certain young adults seem to be at higher risk than others, but a new study provides a clue. In a study published July 13 in the Journal of Adolescent Health, researchers from the University of California San Francisco (UCSF) found that almost one in three adults aged 18 to 25 may be medically vulnerable to severe Covid-19 illness, meaning being hospitalized, admitted to the intensive care unit (ICU), or even dying. Smoking and/or vaping was responsible for most of that vulnerability.

The UCSF study didn’t actually look at Covid-19 patients, so the data are still theoretical but “young adults who smoke would be more vulnerable to the more serious aspects of Covid-19,” says Sally H. Adams, PhD, lead author of the study. (Find out whether vaping can make Covid-19 symptoms worse.)

Smoking rates among young adults

Overall rates of smoking hit a record low in 2018 with 14 percent of adults over 18, or 34 million people, saying they smoked cigarettes, according to the Centers for Disease Control and Prevention. However, some research indicates more young adults than adolescents are starting to smoke or vape. Vaping increased in young adults aged 18 to 24 from 5 percent in 2017 to nearly 8 percent in 2018.  Typically, adolescents are at the highest risk of initiating one or both of these habits. (Here are 8 vaping statistics that may shock you.)

Study after study has shown that people are more at risk from Covid-19 the older they get. “Young age is beneficial, when you get Covid-19,” says Aaron Glatt, MD, a spokesperson for the Infectious Diseases Society of America (IDSA). “But with every decade, it’s more likely you’ll get more symptomatic as well as more serious symptoms.” (Here are the 11 signs you may have already had Covid-19.)

That doesn’t mean anybody has a get-out-of-jail-free card, he adds (though women seem to have some sort of protective advantage). While not as common, younger people can still be hospitalized and even die of Covid-19. According to preliminary data from the CDC, in the week ending June 27, there were 34.7 hospitalizations per 100,000 of the population for people aged 18-29. This is a 299 percent increase in the rate of hospitalizations in that age group since mid-April. (This will tell you more about who’s more likely to die of Covid-19.)

Why they did this Covid-19 study

The world tends to lump millennials, born between 1981 and 1996, in one category. Today, the age range for this group is roughly 24 to 40 years old. But what about the slightly younger age category, say 18 to 25? Researchers have not probed this demographic in relation to Covid-19 nearly as much, says Adams.

“They are developmentally different from older adults and have different lifestyles, health patterns, and health care needs than those a little older, yet they have more barriers to health care,” says Adams, who is a specialist in the division of adolescent and young adult medicine at the University of San Francisco.

More information on this group could highlight ways to reduce their risk and form public health strategies. (Here are the health issues millennials need to stop ignoring.)

How they conducted the study

The CDC has identified smoking as one of the factors that can up your risk for more serious Covid-19 illness. Not much research has looked into smoking and Covid-19 specifically, although one meta-analysis, published May 11 in Nicotine & Tobacco Research did find that serious Covid-19 illness was more common among smokers.

Adams and her colleagues didn’t look specifically at Covid-19 patients (there isn’t much data yet, she explains). Instead, the study used national data from about 8,400 men and women aged 18 to 25 collected between 2016 and 2018. The researchers looked at rates of smoking in the last 30 days as well as health conditions like asthma and immune disorders that can also raise your risk for severe Covid-19 illness.

man holding a cigarette in his mouth in a dark roomBistarelli Nicolas / EyeEm/Getty Images

Some young adults are “medically vulnerable” to Covid-19

Overall, 32 percent of the people in the database were considered “medically vulnerable” for Covid-19 based on CDC risk factors. (Medical vulnerability just means you may be more vulnerable to severe Covid-19 illness because of a medical condition or smoking/e-cigarette use, explains Adams.)

But if you dropped smokers out of the sample, “the vulnerability estimate is cut in half—from 32 percent to 16 percent,” she notes. Smoking in the past 30 days dwarfed any other risk factor, although, in general, young people have fewer of the underlying conditions that affect older people, she says. (Find out how to live longer, according to science.)

Understanding the study’s findings

The study results shouldn’t be surprising, says Dr. Glatt, who is also chairman of medicine and hospital epidemiologist at Mount Sinai South Nassau and professor of medicine at Icahn School of Medicine at Mount Sinai in New York City. “Smoking is one of the most horrific if not the single most horrific thing a person can do to themselves,” he emphasizes. (Here are the 15 ways the body heals itself after you quit smoking.)

Almost right away, smoking or vaping affects your lung tissue and diminishes your oxygen capacity, says Adams. It decreases your airways and immune function in your respiratory system and the respiratory system, of course, is the main target of SARS-CoV-2, the virus that causes Covid-19. (This is what SARS, MERS, and Covid-19 have in common.) Not to mention all the other long-term health ills smoking can cause, from heart disease to many different types of cancer.

The takeaway: Don’t smoke or vape

If you already smoke or vape, stop, and if you haven’t yet started, don’t. “I understand how difficult it is to get off an addiction but we need to educate people,” says Dr. Glatt. “These are lifelong horrific risk factors that you’re adding to yourself. You can’t do much about genes, but you can stop smoking.”

“Some health problems are modifiable and some are not and smoking is modifiable,” adds Adams. “It’s a super important part of health over your life course. Smoking is related to all these really negative health outcomes that tend to build over the age span.” (Get advice on how to quit smoking or vaping.)

Remember, protect yourself from Covid-19

Covid-19 is streaking up to the four million mark in the United States, but that doesn’t mean you have to get it. You can reduce your odds of getting infected with three simple measures: wear a mask, social distance with or without masks, and wash your hands frequently, says Dr. Glatt. You can also use hand sanitizer if you don’t have access to soap and water.

And social distancing means above all staying away from crowded spaces, especially indoor spaces. (There are the public places doctors avoid during coronavirus.)

If you’re young, you still have a lower risk of getting severely ill or dying from Covid-19, but you can easily pass it on to others who are not as healthy, even if you don’t have any symptoms. Here’s more about how to prevent coronavirus.

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Amanda Gardner
Amanda Gardner is a freelance health reporter whose stories have appeared in cnn.com, health.com, cnn.com, WebMD, HealthDay, Self Magazine, the New York Daily News, Teachers & Writers Magazine, the Foreign Service Journal, AmeriQuests (Vanderbilt University) and others. In 2009, she served as writer-in-residence at the University of Wisconsin School of Medicine and Public Health. She is also a community artist and recipient or partner in five National Endowment for the Arts grants.