Smoking a factor in young adult vulnerability to severe COVID-19

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It has become almost common knowledge that young people are less vulnerable to severe coronavirus infections, writes Aria Bendix for Business Insider US. A study from the University of California, San Francisco, determined that one in three young adults is vulnerable to severe COVID-19 cases and smoking is by far the most prevalent risk factor.

US adults from 18 to 49 made up around 25% of hospitalised coronavirus patients in March, whereas those 65 and older represented around 43%, according to the US Centers for Disease Control and Prevention. US adults 18 to 44 years old made up just 2% of coronavirus deaths from February to May, while people 65 and above represented nearly 80%.

But certain factors that can put anyone at risk of serious illness, regardless of age. The University of California researchers found that among young adults aged 18 to 25 years, a third are vulnerable to severe Covid-19 cases. The study findings were published on 13 July in the Journal of Adolescent Health.

Patients were considered vulnerable if they had least one risk factor, including a smoking habit or chronic illness like heart disease, diabetes, asthma, obesity, autoimmune disease, or liver problems, according to Business Insider.

Smoking the most prevalent risk factor

The researchers discovered that smoking was by far the most prevalent risk factor for people in their late teens and 20s. Of the roughly 8,400 young adults in the study, around 25% said they had smoked tobacco, e-cigarettes, or cigars in the last 30 days.

By contrast, only about 16% reported having a chronic illness. Asthma was by far the most common: around 9% of young adults reported that they were asthmatic. That's compared to around 12% who said they'd smoked tobacco in the last 30 days and around 7% who said they'd used e-cigarettes.

"The risk of being medically vulnerable is halved when smokers, including e-cigarette users, are removed from the sample," the researchers wrote. Only about one in six young adults who didn't smoke were vulnerable to severe COVID-19 illness, the study found.

The findings came just days after the World Health Organisation warned about the link between smoking and severe coronavirus cases, Business Insider reports.

"Smoking kills eight million people a year, but if users need more motivation to kick the habit, the pandemic provides the right incentive," WHO Director-general Tedros Adhanom Ghebreyesus said at a press briefing last Friday. "Evidence reveals that smokers are more vulnerable than non-smokers to developing a severe case of COVID-19."

Smoking habits differ among men and women 

The University of California, San Fransisco, study found that the risk of severe coronavirus infections from smoking or e-cigarette use was highest among young, white males with lower incomes who were uninsured for at least part of the year.

Around 16% of the young adults who reported smoking in the study were men. Only 9% were young women.

But women in the study had higher rates of asthma and autoimmune conditions like lupus or rheumatoid arthritis. On the whole, that mostly offset the fact that fewer women smoke: 30% of young women in the study were vulnerable to severe COVID-19 infections compared to 33% of young men.

Since the coronavirus attacks the respiratory system first, patients who already suffer from smoking-related lung damage or inflammation could develop more severe respiratory problems as a result of COVID-19.

Research also suggests that smokers have higher expressions of ACE2 receptors – the cell receptors that the coronavirus uses to invade the body – in their airways. People with more ACE2 receptors seem to have a higher risk of severe COVID-19 infections as well.

But even young patients without a smoking habit or underlying health conditions could still be at risk of a serious case of COVID-19. People ages 18 to 29 make up more than four times as many coronavirus hospitalisations as they did a few months ago: around 38 hospitalisations out of every 100,000 people as of July 4, compared to nine hospitalizations out of every 100,000 people on April 18.


Full report on the Business Insider site


Medical Vulnerability of Young Adults to Severe COVID-19 Illness—Data From the National Health Interview Survey

Journal of Adolescent Health, Published 13 July 2020



Sally H Adams, M Jane Park, Jason P Schaub, Claire D Brindis and Charles E Irwin Jr.


COVID-19 morbidity and mortality reports in the U.S. have not included findings specific to young adults. The Centers for Disease Control and Prevention provides a list of conditions and associated behaviors, including smoking, conferring risk of severe COVID-19 illness regardless of age. This study examines young adults' medical vulnerability to severe COVID-19 illness, focusing on smoking-related behavior.


A young adult subsample (aged 18-25 years) was developed from the National Health Interview Survey, a nationally representative data set, pooling years 2016–2108. The medical vulnerability measure (yes vs. no) was developed, guided by the Centers for Disease Control and Prevention risk indicators.

The estimates of medical vulnerability were developed for the full sample, the nonsmoking sample, and the individual risk indicators. Logistic regressions were conducted to examine differences by sex, race/ethnicity, income, and insurance.


Medical vulnerability was 32% for the full sample and half that (16%) for the nonsmoking sample. Patterns and significance of some subgroup differences differed between the full and the nonsmoking sample. Male vulnerability was (33%) higher than female (30%; 95% CI: .7–.9) in the full sample, but lower in nonsmokers: male (14%) versus female (19%; 95% CI: 1.2–1.7).

The white subgroup had higher vulnerability than Hispanic and Asian subgroups in both samples – full sample: white (31%) versus Hispanic (24%; 95% CI: .6–.9) and Asian (18%; 95% CI: .4–.5); nonsmokers: white (17%) versus Hispanic (13%; 95% CI: .06–.9) and Asian (10%; 95% CI: .3–.8).


Notably, lower young adult medical vulnerability within nonsmokers versus the full sample underscores the importance of smoking prevention and mitigation.


1 in 3 young adults may be vulnerable to severe Covid-19, US study finds. Smoking could be to blame


Medical Vulnerability of Young Adults to Severe COVID-19 Illness – Data From the National Health Interview Survey


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