Additional file 1 of Protective action of natural and induced immunization against the occurrence of delta or alpha variants of SARS-CoV-2 infection: a test-negative case-control study

Additional file 1: Trend of new infections sustained by delta and alpha variants observed between May and July 2021 (Fig. S1); Influence of a potential unmeasured confounder on the relationship between complete vaccination (exposure) and risk of infection due to delta variant, as compared to alpha variant (outcome) (Fig. S2); Main effects of partial and complete vaccination on the onset of new infections caused by delta and alpha variants. Time-windows of 7 and 21 days from vaccine inoculation until immune response (alternative to 14 days of the main analysis), were assumed (Table S1); Comparing selected characteristics of citizens who had at least a positive molecular test of nasopharyngeal swab during the vaccination campaign according whether the corresponding whole-genome sequencing was obtained or less (Table S2); List of conditions used for typifying the study populations (Table S3); SARS-CoV-2 testing and variant identification methods used by the laboratories accredited from Health authorities of Lombardy Region (Annex S1); Details of the rule-out approach applied for the residual unmeasured confounding analysis (Annex S2).