As the COVID-19 pandemic continues to spread, researchers are examining reasons why various countries were impacted differently. It has been suggested that the severity of COVID-19 is higher in countries that do not have a history of Bacillus Calmette–Guerin (BCG) vaccination programs. Clinical trials are underway to investigate the possibility that they confer some immunity to COVID-19.
Mohamed Abukar, MSc, GlobalData Clinical Trials Analyst at GlobalData, comments: “The BCG vaccination has been suggested to induce heterologous immunity against non-mycobacterial pathogens. There are multiple clinical trials to investigate the relationship between BCG vaccination and COVID-19 immunity. Two of these studies are the Phase III BRACE clinical trial, and the Phase III BCG-CORONA trial. These are investigating if BCG vaccination in healthcare workers affords a level of innate immunity against COVID-19.
“Both are placebo-controlled trials that are administering the BCG vaccine to one cohort and a placebo control to the other. The patient populations of the two studies differ slightly, as the BRACE study is administering the vaccine to all healthcare workers whereas the BCG-CORONA trial is only administering the vaccine to health personnel who are taking care of patients with a COVID-19 infection. It is therefore probable that the participants of the BCG-CORONA trial will have a higher level of exposure to coronavirus, and the study should be able to provide a better indicator of the BCG vaccine’s potential protective effects.
“The two studies are both measuring the levels of absenteeism over six months to determine whether there is a significant difference in the level of incidence of COVID-19 between the experimental and placebo cohorts. Both these studies are in non-COVID-19 infected subjects.”
The Baylor College of Medicine and Ain Shams University are both conducting similar trials in which the patient population consists of health workers, with an experimental BCG vaccination arm and a placebo comparator arm, and the primary outcome of both of these studies is the incidence of COVID-19. There is also a study in the Netherlands sponsored by the Radboud University Medical Centre that aims to test the effectiveness of the BCG vaccine against COVID-19 in an elder patient cohort, where participants are ages 60 years or older. The study aims to measure if the BCG vaccine reduces the rate of hospital admissions in elderly patients.
Another study in Egypt sponsored by Assiut University will assess the severity of COVID-19-positive patients ages 12–80 years who have previously been vaccinated with a BCG vaccine. This study will be very useful in assessing if the BCG vaccination decreases the impact of the disease, as opposed to whether the vaccine offers immunity.
Abukar concludes: “Taken together, the results of all the listed trials could provide essential data in determining whether the BCG vaccine provides a level of immunity or protection against COVID-19. A positive correlation could prove to be key in combating COVID-19, as the BCG vaccine has a well-documented safety profile. Furthermore, the vaccine already has well-established production routes that would enable quick delivery to all those who require it.”
While this would not be a direct vaccine against the COVID-19 virus, it could provide a level of protection against COVID-19 that could reduce the mortality of the disease in the population.