Active tobacco smoking is associated with lower risk of acquiring SARS-CoV-2 infection among people living with HIV

Abstract Importance: Information about risk factors for SARS-CoV-2 infection and COVID-19 outcome among people living with human immunodeficiency virus (PLWH) is limited. Furthermore, the impact of smoking on the risk of developing COVID-19 is unclear and has been a matter of controversy.Objective: To evaluate the relationship between current tobacco smoking and the probability of SARS-CoV-2 infection acquisition among PLWH.Design: Retrospective nested case-control study performed within a cohort of 702 PLWH.Settings: University Hospital in Spain (February-October 2020).Participants: Cases were the 18 patients from this cohort with a confirmed diagnosis of COVID-19. Control group included the remaining 684 PLWH without a diagnosis of COVID-19.Exposure: Active tobacco smoking vs. non-smoking, using self-reported electronic health record data.Outcome and Measure: Development of COVID-19. Diagnosis of COVID-19 was established by the detection of SARS-CoV-2 RNA or antigen by PCR or EIA, respectively, or by the presence of plasma SARS-CoV-2 antibodies by ECLIA.Results: In 11 (61.1%) of the 18 patients, COVID-19 diagnosis was based on PCR, 4 (22.2%) on antigen and 3 (16.7%) on serology determinations. In the control group, 380 (54.1%) individuals were also tested. Regarding clinical spectrum, 2 (11.1%) patients were asymptomatic, 12 (66.6%) had upper-respiratory tract infections and 2 (11.1%) had viral pneumonia and one (5.6%) individual showed extra respiratory symptoms. One (5.6%) patient developed severe pneumonia and died. Three hundred and sixty-nine (52.6%) individuals were active smokers, 2 (11.1%) at the COVID-19 diagnosis and 367 (54.1%) in control group (p=0.001). In the bivariate analysis, only tobacco smoking was associated with a greater risk of COVID-19 [unadjusted OR=9.41 95% Confidence Interval (95% CI, 2.15-41.24); p=0.003]. Multivariate analysis, adjusted by sex, tobacco smoking and Charlson index, showed that tobacco smoking was independently related to a higher probability of SARS-CoV2 infection [aOR=9.42 (95% CI 2.15-41.33), p = 0.003].Conclusion and Relevance: Active tobacco smoking is associated with a lower incidence of SARS-CoV-2 infection in PLWH. The underlying mechanisms by which tobacco smoking may protect against SARS-CoV-2 infection should be further investigated. In the meanwhile, public-facing messages about a protective effect of tobacco smoking on the risk of COVID-19 must be avoided.