A new study said smokers and former smokers, face twice the risk of contracting severe cases of the COVID-19 coronavirus than non-smokers.
Those who vape are also at great risk, said researchers at University of California, in San Francisco.
“Our analysis confirms that smoking is a risk factor for progression of COVID-19, with smokers having 1.91-times the odds of progression in COVID-19 severity than never smokers.
They also found that when the disease worsens, current or former smokers had more acute or critical conditions or death. Overall, smoking was associated with almost a doubling of the risk of disease progressing.
The report was published May 12, 2020, in Nicotine & Tobacco Research.
“Smoking is associated with substantially higher risk of COVID-19 progression,” said Stanton A. Glantz, PhD, professor of medicine and director of the UCSF Center for Tobacco Control Research and Education.
Smoking and e-cigarette use increase the risk and severity of pulmonary infections because of damage to upper airways and a decrease in pulmonary immune function in general, although these effects have not yet been studied for SARS-COV-2, the virus that causes COVID-19.
Smokers have a known higher risk of infection and mortality from MERS-COV, a viral respiratory illness caused by a different coronavirus.
In the new meta-analysis, the authors identified 19 peer-reviewed scientific papers published in PubMed as of April 28, 2020, that included data on smoking behaviour and severity of COVID-19.
The studies, from China, Korea and the United States, were mostly based on hospitalised patients, although two studies included both hospitalised patients and outpatients.
Reviewed studies used a variety of definitions of “smoking,” sometimes including both current and former smokers. There was also variability in how disease “progression” was defined. In addition, the levels of smoking reporting were below the levels reported in the population.
A total of 11,590 patients were ultimately identified for the study: 2,133 (18 percent) experienced disease progression, and 731 (6.3 percent) had a history of smoking.
Among smokers, 218 patients (29.8 percent) experienced disease progression, compared with 17.6 percent of non-smoking patients.