Current Smokers at Higher Risk of Developing Severe COVID-19, Study Finds

Smoking tobacco increases a person’s risk of COVID-19 infection, as well as the severity of the disease, according to a study published in the journal Thorax last week.

Researchers from King’s College London collected data from 2.4 million users of the COVID Symptom Study App. Users self-identified as smokers or non-smokers when they first started using the app. Each day between March 24 and April 23, 2020, users reported their physical condition and answered a series of questions including a report on 14 potential COVID-19 symptoms, hospital attendance, and COVID-19 test results.

Current smokers were 14% more likely than non-smokers to experience fever, persistent cough, and breathlessness. Smokers also appeared to experience more symptoms. Current smokers were 29% more likely to report more than five symptoms associated with COVID-19, and 50% more likely to report more than 10.

“Naturally, everybody is sort of running toward the fire to put it out and focusing every available health care resource on trying to control the pandemic,” study co-author Dr. Nick Hopkinson, who is the medical director of the British Lung Foundation, tells Verywell. “When people are thinking about prevention, they tend to think about things that will happen a long way down the line and it always seems more important to focus on acute treatment. But if you invest in smoking cessation, you get returns within that year."

How Smoking Impacts COVID-19 Infection

Studies from early on in the pandemic suggested that smokers experience a lower risk of COVID-19 infection, based on the number of smokers researchers recorded in hospitals. Others claimed that nicotine could be a useful therapeutic option for decreasing inflammation. Sven Eric Jordt, PhD, associate professor in anesthesiology at Duke University School of Medicine in North Carolina, says that these studies had poor methods and were misleading about the harms of smoking. This new study, he says, is better aligned with what decades of research show about the effects of smoking.

“This is correcting those earlier studies which were very poorly done,” Jordt tells Verywell. “Smoking makes things worse—it makes you more susceptible and leads to poor outcomes compared to non-smokers.”

Smoking can damage airways, harm immune response, and make the lungs more susceptible to infection. Inhaled toxins and smoke from cigarettes and e-cigarettes can make white blood cells less effective at recognizing and neutralizing pathogens. Jordt says that weakening the immune system in this way often makes it more challenging for the body to combat viral infections, like influenza and COVID-19.

This means smokers who are exposed to the virus are more likely to develop a severe infection. The King’s College study indicates that current smokers who tested positive for the virus are twice as likely to be hospitalized for the illness.

Though bleak, Hopkinson says some of the negative effects of smoking decrease almost immediately after cessation. The decision to quit smoking during the course of the pandemic can have quick and significant implications for your likelihood of developing lung and heart disease, as well as developing severe illness from COVID-19.

Questions To Be Answered

Despite the study’s robust sample size, it does not include information about the ethnic, racial, or socio-economic make-up of the study population. Hopkinson says the team appreciates the importance of tracking disparities in COVID-19 infection and has collected this information for some of the subjects, though the data hasn’t been published yet.

“We very much regret not having done it because there’s no doubt that the pandemic has highlighted and to some extent driven by all sorts of socioeconomic factors,” Hopkinson says.

In the U.S., Jordt says researchers should also consider how various methods of smoking create different health outcomes. Menthol cigarettes, which are banned in the U.K. and several other countries, are considered to be more dangerous than regular cigarettes because menthol reduces the harshness of cigarette smoke, which makes it more appealing to smoke regularly and inhale deeply into the lungs. In the U.S., nearly 9 out of 10 Black smokers use menthol cigarettes, per a Truth Initiative report, meaning they may be at an even higher risk.

Researchers are still trying to understand how e-cigarettes, vaping, and different types of cigarettes may contribute to COVID-19 outcomes.

Public Health Messaging

In addition to the increased risk of contracting COVID-19, smoking has been shown to cause cancer, heart disease, stroke, diabetes, and more. As healthcare systems in many cities across the U.S. and the world grapple with the influx of COVID-19 patients, the need to provide care for people with non-COVID-19-related medical emergencies can be an added burden. Hopkinson says that if people stop smoking, they can reduce their chances of hospitalization.  

Smoking may also lead to a higher chance of transmitting COVID-19 due to coughing and high hand-to-mouth interaction.

Given the longevity and severity of the COVID-19 pandemic, the study authors recommend that public health officials continue to encourage people to quit smoking, for the sake of the individual and the population. “A holistic pandemic response will include helping people to quit smoking to reduce their chance of getting the virus now,” Hopkinson says.

In the U.S., Jordt says it’s important to educate people on the ways that smoking cessation can improve lung and immune system health.  

“The Centers for Disease Control and Prevention (CDC) should state much more clearly and appeal to people that they really need to use this incidence of the pandemic to quit smoking,” Jordt says. “And they should provide information about the avenues to do this.”

You can find information about how to quit smoking and resources at the CDC website here.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.