INS and type 2 diabetes mellitus: For T2DM, the most important combination is vaccine absence + age ≥65 years + DM duration ≥10 years + insulin that increased the risk of lethal outcome compared to the individual risk of these factors in 5–7, 7–13, 11–19, and 16–28 times, respectively (based on boards of ORs and CIs; CIs do not intersect).