Background and aims: Although obesity has been confirmed as a risk factor for SARS-CoV-2 infection and its severity, the role of post-bariatric surgery (BS) variables and the infection is unclear. We, therefore, aimed to study comprehensively the relationship between the extent of weight reduction after surgery and other demographic, clinical, and laboratory variables with the rates of SARS-CoV-2 infection. Methods: A population-based cross-sectional study was performed, utilizing advanced tracking methodologies on the computerized database of a nation-wide health maintenance organization (HMO). The study population included all HMO members aged ≥18 years that had been tested at least once for SARS-CoV-2 during the study period and underwent BS at least one year before their testing. Results: Of the total 3038 individuals who underwent BS, 2697 (88.78%) were positive for SARS-CoV-2 infection and 341 (11.22%) were negative. Multivariate regression analysis demonstrated that the body mass index and the amount of weight reduction after the BS were not related to the likelihood of SARS-CoV-2 infection. Post-operative low socioeconomic status (SES) and vitamin D3 deficiency were associated with significant and independent increased rates of SARS-CoV-2 infection (odds ratio [OR] 1.56, 95% confidence interval [CI], 1.19–2.03, p < 0.001; and OR 1.55, 95% CI, 1.18–2.02, p < 0.001; respectively). Post-operative physical activity > 3 times/week was associated with a significant and independent reduced rate of SARS-CoV-2 infection (OR 0.51, 95% CI, 0.35–0.73, p < 0.001). Conclusion: Post-BS vitamin D3 deficiency, SES, and physical activity, but not the amount of weight reduction, were significantly associated with the rates of SARS-CoV-2 infection. Healthcare workers should be aware of these associations after BS and intervene accordingly.