COVID-19, smoking, and inequalities: a cross-sectional survey of adults in the UK
Authors: Jackson Sarah E. , Brown Jamie , Shahab Lion , Steptoe Andrew , Fancourt Daisy 
Published: May 2020

Objectives

To examine associations between smoking and COVID-19 relevant outcomes, taking into account the influence of inequalities and adjusting for potential confounding variables.

Design

Online cross-sectional survey.

Setting

UK.

Participants

53,002 men and women aged ≥18y.

Main outcome measures

Confirmed and suspected COVID-19, worry about catching and becoming seriously ill from COVID-19, and adherence to protective behaviours. Socioeconomic position was defined according to highest level of education (post-16 qualifications: yes/no).

Results

Compared with never smokers (0.3% [95%CI 0.2-0.3%]), prevalence of confirmed COVID-19 was higher among current (0.6% [0.4-0.8%]) but not ex-smokers (0.2% [0.2-0.3%]). The associations were similar before (current: OR 2.14 [1.49-3.08]; ex-smokers: OR 0.73 [0.47-1.14]) and after (current: OR 1.79 [1.22-2.62]; ex-smokers: OR 0.85 [0.54-1.33]) adjustment for potential confounders. For current smokers, this was moderated by socioeconomic position, with higher rates relative to never smokers only seen in those without post-16 qualifications (OR 3.53 [2.04-6.10]). After including suspected cases, prevalence was higher among current smokers (11.2% [10.6-11.9%], OR 1.11 [1.03-1.20]) and ex-smokers (10.9% [10.4-11.5%], OR 1.07 [1.01-1.15]) than never smokers (10.2% [9.9-10.6%]), but remained higher only among ex-smokers after adjustment (OR 1.21 [1.13-1.29]). Current and ex-smokers had higher odds than never smokers of reporting significant stress about catching (current: OR 1.43 [1.35-1.52]; ex-smokers: OR 1.15 [1.09-1.22]) or becoming seriously ill from COVID-19 (current: OR 1.34 [1.27-1.43]; ex-smokers: OR 1.22 [1.16-1.28]). Adherence to recommendations to prevent the spread of COVID-19 was generally high (96.3% [96.1-96.4%]), but lower among current than never smokers (OR 0.70 [0.62-0.78]).

Conclusions

When assessed by self-report in a population sample, current smoking was independently associated with confirmed COVID-19 infection. There were socioeconomic disparities, with the association only apparent among those without post-16 qualifications. Smokers reported lower adherence to guidelines despite being more worried than non-smokers about catching or becoming seriously ill from COVID-19.

Registration

The analysis plan was pre-registered on Open Science Framework (https://osf.io/pcs49/).

What is already known on this topic

Former or current smoking can increase the risk of respiratory viral and bacterial infections and is associated with worse outcomes for those infected.

However, data from several countries indicate that rates of current smoking are substantially lower among hospitalised COVID-19 patients than would be expected based on population-level smoking prevalence.

What this study adds

Data from a large population-based sample of adults in the UK conflict with the hypothesis that smoking is protective against COVID-19 infection; rather, we found that current smoking was independently associated with increased odds of confirmed COVID-19 infection after adjusting for relevant confounders.

Socioeconomic disparities were evident, with the association between smoking and confirmed COVID-19 only apparent among those without post-16 qualifications.

Smokers reported lower adherence to guidelines despite being more worried than non-smokers about catching or becoming seriously ill from COVID-19.