{"doi":"10.1093/ntr/ntac090","title":"Tobacco Smoking and Risk of SARS-CoV-2 Infection and Disease Severity Among Adults in an Integrated Healthcare System in California","abstract":"INTRODUCTION: The relationship between tobacco smoking status and SARS-CoV-2 infection and coronavirus disease 2019 (COVID-19) severity is highly debated. We conducted a retrospective cohort study of >2.4 million adults in a large healthcare system to evaluate whether smoking is associated with SARS-CoV-2 infection and disease severity. AIMS AND METHODS: This retrospective cohort study of 2,427,293 adults in KPNC from March 5, 2020 (baseline) to December 31, 2020 (pre-vaccine) included smoking status (current, former, never), socio-demographics, and comorbidities from the electronic health record. SARS-CoV-2 infection (identified by a positive PCR test) and COVID-19 severity (hospitalization, ICU admission or death ≤ 30 days of COVID-19 diagnosis) were estimated in time-to-event analyses using Cox proportional hazard regression models adjusting for covariates. Secondary analyses examined COVID-19 severity among patients with COVID-19 using logistic regression. RESULTS: During the study, 44,270 patients had SARS-CoV-2 infection. Current smoking was associated with lower adjusted rates of SARS-CoV-2 infection (aHR = 0.64 95% CI: 0.61-0.67), COVID-19-related hospitalization (aHR = 0.48 95% CI: 0.40-0.58), ICU admission (aHR = 0.62 95% CI: 0.42-0.87), and death (aHR = 0.52 95% CI: 0.27-0.89) than never-smoking. Former smoking was associated with a lower adjusted rate of SARS-CoV-2 infection (aHR = 0.96 95% CI: 0.94-0.99) and higher adjusted rates of hospitalization (aHR = 1.10 95% CI: 1.03-1.08) and death (aHR = 1.32 95% CI: 1.11-1.56) than never-smoking. Logistic regression analyses among patients with COVID-19 found lower odds of hospitalization for current versus never-smoking and higher odds of hospitalization and death for former versus never-smoking. CONCLUSIONS: In the largest US study to date on smoking and COVID-19, current and former smoking showed lower risk of SARS-CoV-2 infection than never-smoking, while a history of smoking was associated with higher risk of severe COVID-19. IMPLICATIONS: In this cohort study of 2.4 million adults, adjusting for socio-demographics and medical comorbidities, current tobacco smoking was associated with a lower risk of both SARS-CoV-2 infection and severe COVID-19 illness compared to never-smoking. A history of smoking was associated with a slightly lower risk of SARS-CoV-2 infection and a modestly higher risk of severe COVID-19 illness compared to never-smoking. The lower observed COVID-19 risk for current versus never-smoking deserves further investigation. Results support prioritizing individuals with smoking-related comorbidities for vaccine outreach and treatments as they become available.","journal":"Nicotine & Tobacco Research","year":2022,"id":243782,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":32,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.8378,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":876307,"name":"Natalie E. Slama","orcid":"0000-0002-4930-1061","position":1,"is_corresponding":false},{"id":233919,"name":"Stacey Alexeeff","orcid":"0000-0001-8988-6976","position":2,"is_corresponding":false},{"id":233929,"name":"Lori C. Sakoda","orcid":"0000-0002-0900-5735","position":3,"is_corresponding":false},{"id":876869,"name":"Renee Fogelberg","orcid":null,"position":4,"is_corresponding":false},{"id":226781,"name":"Laura C. Myers","orcid":"0000-0002-2872-3388","position":5,"is_corresponding":false},{"id":299646,"name":"Cynthia I. Campbell","orcid":"0000-0003-1019-5852","position":6,"is_corresponding":false},{"id":625300,"name":"Alyce S. Adams","orcid":"0000-0002-0146-4996","position":7,"is_corresponding":false},{"id":75620,"name":"Judith J. Prochaska","orcid":"0000-0001-7925-326X","position":8,"is_corresponding":false},{"id":315600,"name":"Kelly C. Young‐Wolff","orcid":"0000-0002-6177-534X","position":0,"is_corresponding":true}],"reference_count":44,"raw_metadata":null,"created_at":"2026-07-19T00:23:20.901576Z","pmid":"35368066","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}