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On the relationship between BCG coverage and national COVID‐19 outcome: could ‘heterologous’ herd immunity explain why some countries are better off?
Author(s) -
Lerm M.
Publication year - 2020
Publication title -
journal of internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.625
H-Index - 160
eISSN - 1365-2796
pISSN - 0954-6820
DOI - 10.1111/joim.13198
Subject(s) - herd immunity , medicine , covid-19 , heterologous , immunity , outcome (game theory) , herd , virology , immunology , environmental health , vaccination , veterinary medicine , immune system , outbreak , biology , infectious disease (medical specialty) , disease , genetics , mathematical economics , mathematics , gene
The COVID‐19 pandemic has affected most parts of the global society since its emergence, and the scientific community has been challenged with questions urgently demanding answers. One of the early hypotheses on COVID‐19 outcome was that some protection could be offered by the tuberculosis vaccine (BCG), and several clinical studies were initiated along with the emergence of numerous observational studies on the relationship between BCG and COVID‐19 severity. In the present work, I demonstrate a strong correlation between the number of years that countries implemented BCG vaccination plans and age‐standardized mortality rates during the first months of the pandemic in Europe. Further analyses of age groups in two European countries with comparably few confounding factors and easily identifiable groups of BCG‐vaccinated and non‐vaccinated subgroups suggest a population‐level effect of BCG on national outcomes of COVID‐19. This phenomenon of ‘heterologous herd immunity’ deserves further investigation, both in epidemiological and experimental studies.