Could the tuberculosis vaccine, BCG, become a new weapon in the fight against Covid-19 ? Published in the journal Science Advances on August 5, 2022, a new study shows how this vaccine can produce a “trained immune response“, And this more than 14 months after injection.
This trial, conducted by the Murdoch Children’s Research Institute (MCRI) involved 130 infants, and those selected for vaccination received a BCG injection within 10 days of birth. And 14 months later, researchers found reprogramming in vaccinated children, a process during which genes are turned on or off within a specific blood cell, the monocyte. That is, in addition to altering the DNA of white blood cells for 14 monthsthese strains alter the bone marrow which itself will generate future white blood cells.
“The off-target effects of the BCG vaccine against a range of viruses are partly explained by the reprogramming of how your genes function in the monocyte due to environmental and behavioral factors.”, said Dr. Samatha Bannister. And this reprogramming leads to stronger immunity, for longer.
Beneficial off-target effects of the BCG vaccine are accompanied by an epigenetic signature that lasts more than a year, supporting reports that the vaccine provides additional broad protection against viral infections in infants, adults, and the elderly. https://t.co/kIHR9LEVTkpic.twitter.com/FjEzoaCl07
—Science Advances (@ScienceAdvances) August 8, 2022
These off-target effects – either against one of the other categories of virus, bacteria or fungithan originally expected – were first identified in Africa, where mortality rates were reduced in children vaccinated with BCG. “Off-target effects in Africa were known to last over a year, but previous studies of BCG-associated monocyte signatures have only examined one month and three months post-vaccination in adults.said Professor Boris Nokakovic, of the Murdoch Children. For the first time, we have shown how the BCG vaccine can have lasting effects on the immune system of infants.”
The researchers’ next step? Discover the impact of this immunity formed very early, in childhood and then in adulthood.
92% effectiveness against Covid-19
A other study published on August 15, 2022 in the journal Cell Reports Medicine demonstrated that BCG vaccination could offer a form of protection against Covid-19 and other pathogenic infections, particularly in people with type 1 diabetes.
The team recruited 144 patients for a trial conducted from January 2020 to May 2021: 96 received BCG and 48 received a placebo. “BCG is safe and has a 92% efficacy compared to placebo against Covid-19“, says the study. Indeed, in the cohort that received the BCG vaccine, no one tested positive for Covid-19, compared to five symptomatic positive participants among those who received the placebo.
“The results also suggest protection against other infectious diseases.”, particularly in adults with type 1 diabetes in the United States, the study states. And although the effectiveness of the BCG vaccine takes just over a year to manifest, immunity could last for decades. In France, these conclusions could relaunch the debate around the obligation of BCG, which is not no longer mandatory but only recommended since 2007. According to Santé Publique France, vaccination coverage is now at 58%.
Sources
- Neonatal BCG vaccination is associated with a long-term DNA methylation signature in circulating monocytes, Science AdvancesAugust 5, 2022
- Immune boosting benefits of tuberculosis vaccine seen in infants more than a year after vaccination, EurekAlert!, August 5, 2022
- Multiple BCG vaccinations for prevention of COVID-19 and other infectious diseases in Type 1 diabetes, Cell Reports MedicineAugust 15, 2022