Objectives: To clarify the high variability in Covid-19 related deaths whose origin is unclear. Study Design: Modeling of available data Methods: We used six individual- and country-specific variables to predict the number of population standardized Covid-19 related deaths in 44 European countries using generalized linear models: Percent test-standardized number of SARS-CoV-2-cases, population size, life expectancy, severity of governmental responses, influenza-vaccination coverage and vitamin D status in the elderly. Results: We found that flu-vaccination coverage in the elderly was the most important predictor, together with test-standardized cases and vitamin D status explaining approximately 47% of the variation in Covid-19 related deaths. Higher flu vaccination coverage and low vitamin D status were associated with more Covid-19 related deaths. Life-expectancy, population size and the severity of governments’ responses to the outbreak did not emerge as significant predictors in multivariable modeling. The latter variable even appeared to be completely negligible. Conclusion: Adequate vitamin D levels are important, while − contrary to current opinion − flu-vaccination in the elderly is a putative aggravating factor of Covid-19 related deaths.