The impact and progression of the COVID-19 pandemic in Bulgaria in its first two years

After initially having low levels of SARS-CoV-2 infections for much of the year, at the end of 2020 Bulgaria experienced a major epidemic surge, which caused the highest recorded excess mortality in Europe and among the highest in the word (Excess Mortality Rate, or EMR ∼ 0.25%). Two more major waves followed in 2021, followed by another one in early 2022. In this study we analyze the temporal and spatial patterns of excess mortality at the national and local levels and across different demographic groups in Bulgaria, and compare those at the European level. The country has continued to exhibit the previous pattern of extremely high excess mortality as measured both by crude mortality metrics (EMR ∼ 1.05% up to the end of March 2022) and by standardized ones – Potential Years of Life Lost (PYLL) and Aged-Standardized Years of life lost Rate (ASYR). Unlike Western Europe, the bulk of excess mortality in Bulgaria, as well as in several other countries in Eastern Europe, occurred in the second year of the pandemic, likely related to the differences in the levels of vaccination coverage between these regions. We also observe even more extreme levels of excess mortality at the regional level and in some subpopulations (e.g. total EMR values for males ≥ 2% and EMR values for males aged 40-64 ≥ 1% in certain areas). We discuss these observations in light of the estimates of infection fatality rate (IFR) and eventual population fatality rate (PFR) made early in the course of the pandemic.