Could BCG Vaccination Induce Protective Trained Immunity for SARS-CoV-2?

Area of Science:

• Immunology
• Infectious Diseases
• Vaccinology

Background:

• Trained immunity is a non-specific, memory-like immune response offering broad protection against various pathogens.
• The Bacillus Calmette-Guérin (BCG) vaccine, used for tuberculosis, is known to induce trained immunity.
• The COVID-19 pandemic presents a significant global health challenge with no specific vaccine or treatment.

Purpose of the Study:

• To investigate the potential correlation between BCG vaccination and COVID-19 outcomes.
• To explore if BCG-induced trained immunity could offer protection against SARS-CoV-2 infection.

Main Methods:

• Analysis of COVID-19 positive cases and mortality data across different countries.
• Correlation of epidemiological data with the implementation of BCG vaccination in national programs.

Main Results:

• Countries with universal BCG vaccination policies at birth exhibited lower rates of SARS-CoV-2 contagion.
• A reduced number of COVID-19-related deaths were observed in populations vaccinated with BCG at birth.

Conclusions:

• BCG vaccination at birth may be associated with reduced COVID-19 incidence and mortality.
• Trained immunity induced by BCG could potentially confer partial protection against SARS-CoV-2.