It may not be directly related, but when the pandemic just started, there were questions from patients community if intravesical BCG affects COVID-19 in anyway. I followed up this subject by watching several webinars by urologists discussing potential implication of covid-19 to bladder cancer patients. Most urologists commended there should not be any affects. Dr. Gary Steinburg of NYU said if there were it would be positive affect. I assume that Dr. Steinburg was thinking that intravesical BCG kills cancer cells by invoking immune activities. BCG vaccine has been known to provide protection not only for tuberculosis but also for other infectious diseases such as yellow fever and pneumonia, and immune activity by BCG has shown long durability. For Covid-19, many researchers have observed that those countries with compulsory BCG vaccination programs displayed reduced death rate, i.e. up to 10 times less, compared to those countries such as India with no BCG vaccination program. Accordingly multiple clinical trials had started back in 2020 to see if BCG vaccination will reduce serious disease by Covid-19. One such clinical trial was started by Dr. Ashish Kamat of MD Andersons for health care workers. We should expect the result sometime this year. It may be a mute point now as drug companies were able to develop vaccines for Covid-19 but at the onset of the pandemic, some general doctors in Japan tried to hoard intravesical BCG when the news of possible benefit of BCG vaccine against COVID-19. Tokyo BCG company stopped selling intravesical BCG for general doctors as the concern for intravesical BCG shortage for bladder cancer.
In terms of the effect of BCG vaccine against cancers including bladder cancer, a study was conducted in the US with 60 years follow up involving about 3,000 people (about 1500 with BCG vaccine and about 1500 in the placebo group). The result showed that it reduced the occurrence of lung cancer but made no difference in other cancers including bladder cancer.
clinicaltrials.gov/ct2/show/NCT04348370 - Clinical Trial to test if BCG vaccine reduces severity of CONVID-19
jamanetwork.com/journals/jamanetworkopen/fullarticle/2751896 - Study if BCG vaccine prevents cancers
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