A list of retrospective observational studies that provided a correlation between smoking and COVID-19 severity and/or mortality

Article title(s)Study settingSample numberPositive smoking status, number (percentage)Smoking and COVID-19 severity, number (percentage)Smoking and COVID-19 mortality, number (percentage)
Associations of clinical characteristics and antiviral drugs with viral RNA clearance in patients with COVID-19 in Guangzhou, China: a retrospective cohort study (X. Chen et al., preprint, DOI: Eighth People’s Hospital (Jan 20 to Mar 15, 2020)28428 (9.9)Asymptomatic2 (7.1)P = 0.838
Mild3 (10.7)
Moderate17 (60.7)
Serious5 (17.9)
Critical1 (3.6)
Preliminary estimates of the prevalence of selected underlying health conditions among patients with coronavirus disease 2019 — United States, February 12–March 28, 2020 (CDC COVID-19 Response Team, 2020)CDC passive surveillance registry (March 28, 2020)74,439Hospitalized (non-ICU)ICU
Former smoker165 (2.3)Former smoker33 (7)7 (1)
Current smoker96 (1.3)Current smoker5 (1)8 (2)
The clinical characteristics of COVID-19: a retrospective analysis of 104 patients from the outbreak on board the Diamond Princess cruise ship in Japan (S. Tabata et al., preprint, DOI: and crew of Diamond Princess cruise ship10418 (17.3)
Risk factors associated with clinical outcomes in 323 COVID-19 patients in Wuhan, China (L. Hu et al., preprint, DOI: Hospital (Jan 8 to Feb 20, 2020)32338 (11.8)Nonsevere12 (7.9)P = 0.123
Severe22 (15.1)
Critical4 (15.4)
Unfavorable outcome12 (19)P = 0.045
Favorable outcome26 (10)
Development and external validation of a prognostic multivariable model on admission for hospitalized patients with COVID-19 (J. Xie et al., preprint, DOI: hospital (Jan to Feb 2020)29910 (3.4)Survival5 (3.5)P = 0.914
Death5 (3.2)
Epidemiologic and clinical features of 125 hospitalized patients with COVID-19 in Fuyang, Anhui, China (Wang et al., 2020b)No. 2 People’s Hospital of Fuyang City (Jan 20 to Feb 9, 2020)12516 (12.8)Noncritical9 (9)P = 0.027
Critical7 (28)
Prognostic value of C-reactive protein in patients with COVID-19 (Luo et al., 2020)Eastern Campus of Renmin Hospital of Wuhan University (Jan 30 to Feb 20, 2024)29821 (7)Recovered13 (6.1)P = 0.295
Died8 (9.5)
Characteristics of patients with COVID-19 during epidemic ongoing outbreak in Wuhan, China (X. Luo et al., preprint, DOI: Campus of Renmin Hospital, Wuhan University (Jan 30 to Feb 25, 2020)40329 (7.2)Recovered20 (6.6)P = 0.421
Died9 (9)
Clinical course and risk factors for mortality of adult Inpatients with COVID-19 in Wuhan, China: a retrospective cohort study (Zhou et al., 2020a)Jinyintan Hospital and Wuhan Pulmonary Hospital (Wuhan, China) who had been discharged or had died by Jan 31, 202019111 (6)OR2.23P = 0.2
95% CI(0.65, 7.63)
Epidemiologic and clinical features of 2019-nCoV acute respiratory disease cases in Chongqing municipality China: a retrospective descriptive multiple-center study (D. Qi et al., preprint, DOI: Central Hospital of Chongqing, Chongqing Three Gorges Central Hospital, and Chongqing Public Health Medical Center (Jan 19 to Feb 16, 2020)26753 (19.9)Nonsevere22 (10.1)P < 0.001
Severe31 (62)
Clinical characteristics of coronavirus disease 2019 in China (Guan et al., 2020b)552 hospitals in China (Dec 11, 2019 to Jan 29, 2020)1099Former Smoker21 (1.9)Former smokerCurrent smoker
Nonsevere12 (1.3)108 (11.8)
Current Smoker137 (12.6)Severe9 (5.2)29 (16.9)
  • CI, confidence interval; OR, odds ratio.