Lower Rate of Daily Smokers With Symptomatic COVID-19: A Monocentric Self-Report of Smoking Habit Study

Abstract

Background: Identification of prognostic factors in COVID-19 remains a global challenge. The role of smoking is still controversial.Methods: PCR-positive in- and outpatients with symptomatic COVID-19 from a large French University hospital were systematically interviewed for their smoking status, use of e-cigarette, and nicotinic substitutes. The rates of daily smokers in in- and outpatients were compared using the same smoking habit questionnaire to those in the 2019 French general population, after standardisation for sex and age.Results: The inpatient group was composed of 340 patients, median age of 66 years: 203 men (59.7%) and 137 women (40.3%), median age of both 66 years, with a rate of 4.1% daily smokers (CI 95% [2.3–6.9]) (5.4% of men and 2.2% of women). The outpatient group was composed of 139 patients, median age of 44 years: 62 men (44.6%, median age of 43 years) and 77 women (55.4%, median age of 44 years). The daily smoker rate was 6.1% (CI 95% [2.7–11.6], 5.1% of men and 6.8% of women). Amongst inpatients, daily smokers represented 2.2 and 3.4% of the 45 dead patients and of the 29 patients transferred to ICU, respectively. The rate of daily smokers was significantly lower in patients with symptomatic COVID-19, as compared to that in the French general population after standardisation by age and sex, with standardised incidence ratios (SIRs) of 0.24 [0.12–0.48] for outpatients and 0.24 [0.14–0.40] for inpatients.Conclusions: Daily smoker rate in patients with symptomatic COVID-19 is lower as compared to the French general population

Cumulative incidence of SARS-CoV-2 infection and associated risk factors among frontline health care workers in Paris: the SEROCOV cohort study

“…An increasing number of studies have reported this reduced risk of SARS-CoV-2 infection in current smokers in different contexts (cross-sectional studies in the general population; cross-sectional, case–control or control studies in different populations) 19 – 24 . Our results from a large multicenter prospective study in a young population of HCWs with 26.9% current smokers support the role of use of tobacco substances as protective against SARS-CoV-2 infection, which may act through the nicotine pathway 25 – 28 . This result should not encourage smoking to limit the risk of COVID-19; indeed, 78,000 deaths per year are due to smoking in France 29 .…”

SARS-CoV-2 seroprevalence in healthcare workers and risk factors

“…Miyara et al also reported that daily smokers are less likely to develop symptomatic or severe SARS-CoV-2 infection compared with the general population. This risk in smokers versus non-smokers is five and four times lower in outpatients and inpatients, respectively ( 9 ). The Italian observational study MUSTANG-OCCUPATION-COVID 19 found that among the current smokers, 19.6% were seropositive whereas 9.2% had not antibodies against SARS-CoV-2 ( 10 ).…”

Nicotine patches in patients on mechanical ventilation for severe COVID-19: a randomized, double-blind, placebo-controlled, multicentre trial

“…The “nicotine hypothesis” linking lower than expected COVID-19 cases among active smokers to putative preventive and therapeutic effects of nicotine against SARS-CoV-2 emerged early in the course of the pandemic [ 3 ]. In the weeks following the pre-print publication of these data, social media platforms like Twitter relayed thousands of messages about the benefits of smoking or vaping in the context of COVID-19 [ 31 , 32 ].…”

“…Early epidemiologic studies documented lower rates of active smokers compared to former or non-smokers in symptomatic COVID-19 patients [ 3 – 9 ], although more severe forms of the disease were reported among smokers or former smokers once infected [ 10 , 11 ]. It was hypothesized that nicotine may interact with SARS-CoV-2 entry in human cells by downregulating the expression of angiotensin converting enzyme 2 (ACE2), the principal receptor for the virus [ 12 – 15 ].…”