• Home
  • Health & Wellness
  • Disclaimer
    • Terms of Use
    • Privacy Policy
    • DMCA Notice
Podcast
  • Home
  • Health & Wellness
  • Disclaimer
    • Terms of Use
    • Privacy Policy
    • DMCA Notice
24/7 Health News
No Result
View All Result
Home Article

BCG: how a century-old vaccine is being used against everything from cancer to autoimmune diseases

February 8, 2023
in Article
0
BCG: how a century-old vaccine is being used against everything from cancer to autoimmune diseases
file 20230207 25 gtgpu9
BCG vaccine scar TuktaBaby/EPA

In March 2020, as the UK was preparing to go into lockdown, two new trials were posted on the clinicaltrials.gov database. The researchers were proposing that BCG, an old vaccine against tuberculosis (TB), should be tested for its protective effect against COVID.

As vaccines tend to activate very specific immune responses against their target disease, why did these scientists believe that BCG might have an effect against this profoundly different pathogen?

In fact, almost since its first use against TB just over 100 years ago, BCG has been known to have “non-specific protective effects”. In other words, it can prevent diseases other than TB.

BCG was developed in France by two doctors, Albert Calmette and Camille Guérin – hence its name: Bacillus Calmette-Guérin. Between 1908 and 1921 Calmette and Guérin repeatedly cultured (on slices of potato) the organism responsible for TB in cattle until it no longer caused disease in animals. It also protected these same animals when they were later challenged with the human version: Mycobacterium tuberculosis.

Camille Guérin, a portrait of Albert Calmette is seen to the right
Camille Guérin, with a portrait of Albert Calmette to the right.
Unknown author/Wikimedia, CC BY

Within a few years, BCG was being injected into children, delivering high levels of protection against TB with few side-effects. In 1931, Calmette suggested that BCG also prevented death from infectious diseases other than TB, an observation partly supported by data from studies in Sweden.

A recent reanalysis of the Swedish data concluded that although there was an element of “healthy vaccinee bias” in some of the data (that is, people in better health are more likely to get vaccinated), the results did support a non-specific protective effect of BCG. Later observations and trials also reported non-specific protective effects of BCG against lung infections unrelated to TB.

The key to BCG’s ability to induce a general state of readiness in the immune system, a phenomenon known as “trained immunity”, is tied to its identity as a live microorganism with a complex outer cell wall. Certain components of this cell wall are detected by the oldest (in evolutionary terms) elements of the immune system, also called the innate response. This interaction programmes innate immune cells to respond more effectively to any microorganism they encounter.

Vaccine against cancer

The beneficial effects of BCG are not restricted to infectious disease. The administration of live or dead bacteria as a treatment for cancer was pioneered in the 19th century. The effects against cancer of mycobacteria in particular were noted in the early 20th century, leading to the establishment of BCG delivered directly to the bladder as a treatment against non-muscle invasive bladder cancer – where the cancer cells are only in the inner lining of the bladder. It is still the standard treatment for this type of cancer.

Trials of BCG immunotherapy for other types of cancer have delivered mixed results. Some studies reported a lack of any effect against general malignancies. Others suggested an effect against childhood leukaemia or even a dramatic long-term effect against lung cancer. Direct injection into melanoma lesions has revealed positive results, whereas administration of BCG by the standard injection into the upper arm is less convincing at treating melanoma.

To effectively destroy cancer cells, the immune system deploys many of the same weapons that are also effective against viruses and bacteria that like to live inside our cells. What is more, the trained immunity effect bestowed by BCG either directly or indirectly activates these same weapons. In other words, BCG is “immunostimulatory”.

It may come as a surprise therefore, to discover that some of the non-specific protective effects of BCG work against diseases where the immune system is overactive, or misfiring against the wrong targets. For example, the autoimmune conditions multiple sclerosis and type 1 diabetes. In these cases, BCG is having an opposite and beneficial, immune-dampening, effect.

Studies have shown that BCG can reduce and prevent immune-mediated damage to the nervous system in multiple sclerosis. It can also counteract rogue immune cells that attack insulin production in the pancreas of diabetic patients. In both multiple sclerosis and type 1 diabetes, BCG’s ability to reprogram metabolism in cells as well as its capacity to increase numbers of special immune-dampening T-cells are thought to play key roles.

…and against COVID

And what of BCG vaccination against COVID? Again, the picture is mixed. A recent meta-analysis – where data from several studies are combined and analysed – failed to find an overall protective effect. However, individual trials have reported some success. For example, a reduced risk of COVID six months after vaccination. Or, more dramatically, a 92% efficacy in adults with long-standing type 1 diabetes who were given BCG for the prevention of COVID.

BCG’s tendency to provide variable protection has been known for some time. This is true for its “day job” as a vaccine against TB, as well as for its non-specific protective effects. Several reasons have been proposed for this variability. Previous exposure to other microorganisms, such as bacteria from the same family as BCG, or parasitic worms may lead to the immune system making the wrong sort of response to BCG. Differences in the genetic background of recipients can also lead to less effective immune responses to BCG.

A better understanding of the environment in which BCG works most consistently to deliver its specific and non-specific effects will surely enable the effective use of this most versatile of vaccines in future.

The Conversation

Steven Smith does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ShareTweetSharePin
Previous Post

I treat people with gambling disorder – and I’m starting to see more and more young men who are betting on sports

Next Post

To prevent child sexual abuse, we need to change our thinking — and stop exploitation before it happens

Next Post
To prevent child sexual abuse, we need to change our thinking — and stop exploitation before it happens

To prevent child sexual abuse, we need to change our thinking — and stop exploitation before it happens

Most Read

What causes stuttering? A speech pathology researcher explains the science and the misconceptions around this speech disorder

What causes stuttering? A speech pathology researcher explains the science and the misconceptions around this speech disorder

December 15, 2022
morning back pain

Morning Again Ache Trigger Is Not the Mattress

October 11, 2021
lower back pain relief exercises

5 decrease again ache aid workouts

October 11, 2021
3 years after legalization, we have shockingly little information about how it changed cannabis use and health harms

3 years after legalization, we have shockingly little information about how it changed cannabis use and health harms

October 15, 2021
Nasal vaccines promise to stop the COVID-19 virus before it gets to the lungs – an immunologist explains how they work

Nasal vaccines promise to stop the COVID-19 virus before it gets to the lungs – an immunologist explains how they work

December 14, 2022
bleeding in gum

When The Bleeding in gum Is Severe ?

October 11, 2021
Good Night Sleep

6 Causes of Good Evening Sleep

October 11, 2021

COVID vaccines: how one can pace up rollout in poorer international locations

October 5, 2021
Ten small changes you can make today to prevent weight gain

Ten small changes you can make today to prevent weight gain

October 12, 2021
Support and collaboration with health-care providers can help people make health decisions

Support and collaboration with health-care providers can help people make health decisions

December 16, 2021
Greece to make COVID vaccines mandatory for over-60s, but do vaccine mandates work?

Greece to make COVID vaccines mandatory for over-60s, but do vaccine mandates work?

December 1, 2021

Multiple sclerosis: the link with earlier infection just got stronger – new study

October 12, 2021
News of war can impact your mental health — here’s how to cope

Binge-eating disorder is more common than many realise, yet it’s rarely discussed – here’s what you need to know

December 2, 2022
Nurses’ attitudes toward COVID-19 vaccination for their children are highly influenced by partisanship, a new study finds

Nurses’ attitudes toward COVID-19 vaccination for their children are highly influenced by partisanship, a new study finds

December 2, 2022
Kick up your heels – ballroom dancing offers benefits to the aging brain and could help stave off dementia

Kick up your heels – ballroom dancing offers benefits to the aging brain and could help stave off dementia

January 3, 2023
How hot is too hot for the human body? Our lab found heat + humidity gets dangerous faster than many people realize

How hot is too hot for the human body? Our lab found heat + humidity gets dangerous faster than many people realize

July 6, 2022
The promise of repairing bones and tendons with human-made materials

The promise of repairing bones and tendons with human-made materials

January 4, 2022
As viral infections skyrocket, masks are still a tried-and-true way to help keep yourself and others safe

As viral infections skyrocket, masks are still a tried-and-true way to help keep yourself and others safe

December 14, 2022
How regulatory agencies, not the courts, are imposing COVID-19 vaccine mandates

How regulatory agencies, not the courts, are imposing COVID-19 vaccine mandates

October 24, 2021
Heart disease risk from saturated fats may depend on what foods they come from – new research

Heart disease risk from saturated fats may depend on what foods they come from – new research

November 29, 2021
Late night eating may cause greater weight gain – new research points to why

Late night eating may cause greater weight gain – new research points to why

October 12, 2022

10 Things I Learned During My Body Transformation

October 12, 2021

7 Health Benefits of Sweet Potatoes

October 12, 2021
Nobel prize: how chilli peppers helped researchers uncover how humans feel pain

Nobel prize: how chilli peppers helped researchers uncover how humans feel pain

October 12, 2021
How air filters can make COVID wards safer for patients and staff

How air filters can make COVID wards safer for patients and staff

December 1, 2021
GPs don’t give useful weight-loss advice – new study

GPs don’t give useful weight-loss advice – new study

December 16, 2022
Four ways to avoid gaining weight over the festive period – but also why you shouldn’t fret about it too much

Four ways to avoid gaining weight over the festive period – but also why you shouldn’t fret about it too much

December 22, 2022
Five ways to avoid pain and injury when starting a new exercise regime

Five ways to avoid pain and injury when starting a new exercise regime

December 30, 2022
Why suicide prevention support is crucial for people with fetal alcohol spectrum disorder

Why suicide prevention support is crucial for people with fetal alcohol spectrum disorder

September 28, 2022
Too hot to handle: Climate considerations for youth sport during the hottest years on record

Too hot to handle: Climate considerations for youth sport during the hottest years on record

July 19, 2022
  • Home
  • Health & Wellness
  • Disclaimer

© 2020 DAILY HEALTH NEWS

  • Home
  • Health & Wellness
  • Disclaimer
    • Terms of Use
    • Privacy Policy
    • DMCA Notice

© 2020 DAILY HEALTH NEWS