New research from King's College London investigated whether there is a link between smoking and COVID-19 severity by analyzing data from a self-reporting ZOE COVID Symptom Study app. Earlier, preliminary studies suggested smoking may have a protective effect on COVID-19 severity, but many experts had doubts, and question marks remained.
The new study, published in the journal Thorax, suggests smokers have an increased risk of developing COVID-19 symptoms and are more likely to attend hospitals compared to their non-smoking counterparts.
The authors of the study took data from the ZOE COVID app between March 24 and April 23, 2020, and assessed the outcomes of 2,401,982 participants that self-reported symptoms. Out of the total, 11 percent, were smokers.
Of the participants in the study, a third of them reported feeling physically unwell during this month-long period. However, the smokers were 14 percent more likely to report the classic triad of COVID-19 symptoms – persistent cough, shortness of breath, and fever – compared to their non-smoking counterparts.
Furthermore, smokers were also more likely to report additional symptoms associated with a COVID-19 infection. Smokers were 29 percent more likely to report up to five known COVID-19 symptoms, and 50 percent more likely to report more than 10 symptoms. The authors of the study said that having more of the additional COVID-19 symptoms, such as loss of smell, muscle pain, diarrhea, etc suggested smokers experienced a wider range of symptoms than non-smokers and hence had a more severe COVID experience.
"Some reports have suggested a protective effect of smoking on COVID-19 risk. However, studies in this area can easily be affected by biases in sampling, participation, and response. Our results clearly show that smokers are at increased risk of suffering from a wider range of COVID-19 symptoms than non-smokers," said Dr Mario Falchi, one of the authors of the study, in a press release.
Interestingly, those smokers in the study who had a confirmed COVID-19 positive test were two times more likely to attend hospital than their non-smoking counterparts.
“As rates of COVID-19 continue to rise and the NHS [UK health service] edges towards capacity, it’s important to do all we can to reduce its effects and find ways to reduce hospital admissions. Our analysis shows that smoking increases a person’s likelihood to attend hospitals, so stopping smoking is one of the things we can do to reduce the health consequences of the disease,” lead author Dr Claire Steves concluded.