It’s often spouted that people don’t need to worry about Covid-19 unless they’re old or are already ill with another disease or condition, but that’s not the case at all. New research has suggested that up to one in three people aged 18 to 25 risk falling seriously ill with a Covid-19 infection. 

Based on a nationally representative sample of approximately 8,400 people in the US, scientists at the University of California San Francisco found that 33 percent of males and 30 percent of females appeared to have a “medical vulnerability” to Covid-19, which meant they were significantly more likely to be hospitalized. Their findings were published on Monday in the Journal of Adolescent Health.

People over 65 are more likely to be hospitalized for Covid-19 than younger people. However, Centers for Disease Control and Prevention (CDC) data cited by the researchers suggests the gap has narrowed in recent weeks, with a recent 299 percent increase in hospitalizations for young adults, compared to a 139 percent increase in hospitalizations for older adults.

In mid-April, there were 8.7 hospitalizations per 100,000 people in the 18 to 29 age bracket, versus 128.3 per 100,000 of people over 65. By the end of June, those figures were 34.7 and 306.7, respectively. 

If you’re a young person, these are the risk factors that up your chances of falling severely ill with Covid-19: heart conditions, diabetes, current asthma, immune conditions (such as lupus, gout, rheumatoid arthritis), liver conditions, and obesity. 

Above all, however, the researchers claim that smoking (including e-cigarettes) was one of the most notable risk factors.

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

Out of the young people who were hospitalized with Covid-19, the proportion of smokers (19.8 percent) was higher than the number of people with asthma (8.6 percent), obesity (3 percent), immune disorders (2.4 percent), diabetes (1.2 percent), a liver condition (0.6 percent) and a heart condition (0.5 percent). 

Of course, there are more young people who smoke in the population than, for example, young people with a liver condition, which could partially explain these high numbers for hospitalized smokers. Furthermore, the link between smoking and hospitalizations is only a correlation — a cause-and-effect relationship was not identified by the researchers. 

Nevertheless, the researchers argue the link they found is notable, especially since young people can kick their smoking habit if they want to lower their risk of severe Covid-19. 

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

Recent months have seen a handful of sensational headlines, such as "Smokers four times less likely to contract Covid-19" and "MORE evidence smoking may cut the risk of coronavirus." These headlines are widely considered misleading. There are currently no peer-reviewed studies that directly estimate the risk of hospitalization with Covid-19 among smokers. However, the World Health Organization states: "Smoking is associated with increased severity of disease and death in hospitalized Covid-19 patients."