Growing evidence COVID-19 severity and smoking linked

Public health doctors at Chelsea and Westminster Hospital NHS Foundation Trust and Imperial College London looked at smoking as a risk factor for inpatients with COVID-19. The authors conclude there is growing evidence of an association between smoking, and progressing as an inpatient to more severe forms of the disease—for example, requiring admission to intensive care. 

Since smoking affects the lungs and heart, and some of the conditions worsened by smoking are risk factors for poor outcomes in COVID-19, it is highly plausible that smoking would lead to worse outcomes in COVID-19.

What is the direct evidence?

The team looked at eight reviews (studies which look at smaller studies and draw conclusions).

Public Health Registrar Emily Grundy from Chelsea and Westminster Hospital said: “In six reviews which considered progression to severe disease for inpatients, four found significant association with smoking. For example, one of those found nearly 30% of patients who were ever smokers progressed to severe disease, as opposed to 18% of never smokers.

“Many of the risk factors for COVID-19 can’t be changed, or the reason for them is not understood. Smoking may be the most significant risk factor that is open to individuals to change. There are already good reasons not to smoke, but a higher risk of poor outcomes if you suffer from COVID-19 is another one. 

“An unfortunate consequence of the pandemic has been the curtailing of in-person smoking cessation clinics. While they can be conducted online or by phone, they won’t be accessible for everyone. Smoking cessation is an essential service which must be supported and we strongly advocate for equitable and flexible service provision that supports even the most vulnerable groups, and that these services are tenaciously promoted.”

Reviews sometimes struggled with differing definitions and data quality issues such as to whether smoking history was recorded. 

Emily Grundy commented: “Clinicians need to take an accurate smoking history—which includes asking about the whole range of tobacco and nicotine products such as shisha and e-cigarettes—in a non-judgmental and structured manner so we can provide the best advice and care. Better data is essential to conduct research and provide the best advice and treatment.”

Other findings

The studies found no consistent evidence that smoking increased the risk of hospital admission with COVID-19.  

Smoking, SARS-CoV-2 and COVID-19: A review of reviews considering implications for public health policy and practice. Published in Tobacco Induced Diseases.