Related Experiment Video
Updated: Jun 21, 2025
Protective Efficacy and Pulmonary Immune Response Following Subcutaneous and Intranasal BCG Administration in Mice
Published on: September 19, 2016
Rationale for Randomized Clinical Trials Investigating the Potential of BCG Vaccination in Preventing COVID-19
Magali Noval Rivas1,2, Charles J Rosser3, Moshe Arditi1,2,4
1Department of Pediatrics, Division of Infectious Diseases and Immunology, Infectious and Immunologic Diseases Research Center (IIDRC) and Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
Insights
The Bacillus Calmette-Guerin (BCG) vaccine may offer protection against Coronavirus disease 2019 (COVID-19) by boosting innate immunity. Further clinical trials are needed to confirm its efficacy, especially for high-risk individuals like healthcare workers.
Area of Science:
- Immunology
- Infectious Diseases
- Vaccinology
Background:
- Coronavirus disease 2019 (COVID-19) continues to spread globally, posing a significant threat to public health.
- While COVID-19 vaccines are in development, widespread vaccination will take time, leaving populations vulnerable.
- Frontline healthcare workers face elevated risk of SARS-CoV-2 exposure, necessitating urgent protective strategies.
Purpose of the Study:
- To explore the potential of Bacillus Calmette-Guerin (BCG) vaccination as a protective measure against COVID-19.
- To investigate whether BCG vaccination can provide a nonspecific innate immune boost against SARS-CoV-2 infection.
- To determine the efficacy of BCG in protecting high-risk populations, such as healthcare workers, against COVID-19.
Main Methods:
- Review of epidemiological and observational studies on BCG vaccination and COVID-19 outcomes.
- Hypothesis generation based on BCG's known immunomodulatory effects (trained immunity).
- Proposal for randomized controlled clinical trials to rigorously assess BCG's protective role.
Main Results:
- Existing data suggest a potential protective association between BCG vaccination and reduced COVID-19 incidence.
- BCG vaccination is known to enhance innate immune cell function, conferring nonspecific resistance to viral infections.
- Current evidence is observational and limited by potential biases, precluding causal inference.
Conclusions:
- BCG vaccination warrants investigation as a potential strategy to mitigate COVID-19 spread through innate immune enhancement.
- Randomized controlled trials are essential to validate the hypothesis that BCG protects against COVID-19.
- Prioritizing trials in high-risk groups like healthcare workers is crucial given their exposure levels.
Abstract:
Despite the implementation of mitigation measures, Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is still spreading worldwide, and has caused more than 1 million deaths so far. Although recent reports indicate that three vaccine candidates are effective against SARS-CoV-2, more time is needed to generate enough doses for the general population. Meanwhile, frontline healthcare workers are at high risk of SARS-CoV-2 exposure. To avoid collapse of the medical care system, there is a need to develop novel approaches to limit SARS-CoV-2 spread. Through a process called trained immunity, the Bacillus Calmette-Guerin (BCG) vaccine boosts the action of innate immune cells, resulting in a nonspecific reduction in the incidence of viral infections. Due to this immunomodulatory action, the BCG vaccine is currently used as a therapeutic in bladder cancer. Data collected from epidemiological and observational studies indicate that BCG vaccination might provide protection against COVID-19. While these observations do not provide evidence of causality and are limited by cofounding and intrinsic biases, it is crucial to explore the hypothesis that BCG vaccination may provide a nonspecific innate immune boost and therefore protect against COVID-19 in randomized controlled clinical trials, particularly for people at higher risk of developing COVID-19, such as frontline healthcare workers.
Related Concept Videos
01:30Cancer Vaccines
Cancer vaccines come in two categories: preventive (prophylactic) and treatment (active). Preventive vaccines, such as the Human Papillomavirus (HPV) vaccine, protect against viruses that cause certain...
01:23Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast,...
01:12What is an Experiment?
01:11Blinding
01:51Vaccinations
01:16Clinical Trials
There are four phases in a clinical trial. A phase one...