BCG vaccine for tuberculosis came into existence more than 100 years ago. However hardly people know complete truth about it. Here we will explore in detail about what is BCG vaccine, how and when it should be given and what are the consequences following BCG vaccination.

Tuberculosis vs Covid

In past few years covid has drawn everyone’s eye. But do you know that in year 2020 and 2021 when covid was at peak, even then tuberculosis was the second most leading cause of death from a single infectious agent, after covid!

As per WHO data, mortality rate of untreated TB has been almost 50%. Tuberculosis in kids is even more fatal. In 2016, TB has taken 2.5 lacs lives of children worldwide, in a single year. 

Furthermore, paralysis caused by TB debilitates a child permanently. Co-infection with HIV has made this even more deathly. You can say that tuberculosis is a ‘silent pandemic’. However BCG vaccine for tuberculosis is here for rescue.

BCG Vaccine Full Form

BCG vaccine name stands for “Bacillus Calmette-Guérin”. This is a vaccine for tuberculosis that was developed by 2 scientists Calmette and Guérin” in year 1921. It is derived from a rod shaped bacterium, from which the term “bacillus” takes origin. 

BCG vaccine meaning?


This is a live attenuated vaccine. That means it is composed of live bacteria that is attenuated ( weakened ). This weak bacteria when get in inside human body, can not produce disease. But in response, body defence system generates immunity against it. 

Name of this bacteria present in BCG is ‘mycobacteria’. Mycobacteria cause tuberculosis or TB. Hence BCG vaccine protects against serious TB infection. 

BCG vaccine is given at what age ?

Most of us know that BCG vaccine for tuberculosis is given at birth in developing countries to all newborn babies. Besides, there are special circumstances under which a kid in developed countries needs to take BCG too. 

What is inside BCG vaccine vial?

The vaccine is in the form of freeze dried powder. This powder form of vaccine is reconstituted by mixing with normal saline as diluent. After reconstitution, vial can be utilised maximum up to 4 hours and not more than that. 

How to preserve a BCG vial ?

BCG vaccine is pretty sensitive to both light and heat. To protect it from light, the vaccine is kept inside amber coloured vial. This vial is put away from direct sunlight. 

To keep it heat-safe, health care workers store it  at 2-8 degree Celsius temperature.

What is dose of BCG vaccine for tuberculosis?

Dose of BCG vaccine for tuberculosis is 0.1 ml. Though some manufacturers recommend 0.05 ml dose for infants and 0.1 ml for more than 1 year olds. But studies have established that 0.1 ml of BCG dose at birth is superior compared to 0.5 ml and should be followed. 

How many doses are there in one BCG vial ?

BCG vaccine is being sold as multi-dose vial. One vial has 10 doses. In other words one vial has 1 ml, which is 10 times of a single dose (0.1 ml ). 

As discussed before, diluted vaccine should be used with 4 hours. After which unused vaccine should be discarded. 

That is the reason why vaccine centres assign one particular day of a week for BCG vaccination of all babies. For instance at some centres Thursday is chosen as vaccination day. This is to minimise wastage of vaccine. After all vaccines are by-product of years of hard work and research.

What is the site and route for BCG ?

Site :

People from developing countries have a scar mark on left upper arm. This is nothing but a proof of past anti-tuberculosis vaccination. It is a BCG vaccine scar. Hence the site of BCG vaccine is left upper arm. This spot is preferred in all kids, to maintain uniformity. 

Route :

Route of BCG vaccination is intra-dermal, that is into thin layer of skin. Here needle is held almost parallel to skin surface while injecting. This skill is a little tricky and hence need an expert hand. 

If not given properly then tuberculosis vaccine may become ineffective or may result in more side effects. Hence correct technique is a must, when it comes to BCG vaccine. 

Stages of BCG vaccine scar formation?

BCG vaccine is different from rest of the vaccines in many ways. One fundamental difference is the way our body reacts to it. 

Many often parents are apprehensive that, pus or blister has come up at site of vaccination and what should they do next. Below we have detailed down, what causes this pus and how to deal with it. 


4 stages of BCG scar

After 1-3 weeks of BCG there forms a small elevation on skin at site of injection. This is described as papule, which is around 4-8mm in size.

This papule then takes shape of a blister. Initially blister is filled with clear fluid, which is later is replaced with a pus like material. This is in fact not pus but a ‘caseous tissue’. To put it simply, caseous tissue following BCG is a testimony that, body is forming immunity against TB. 


5-6 weeks post vaccination, this pus like lesion bursts and caseous material is released out. This generates an ulcer and then formation of crust over it.

Gradually over 6 – 12 weeks, there appears a scar at injection site. BCG vaccine is given only once, and afterwards the scar stays life long. 

What should parents do when there is pus like leison or discharge or ulcer following BCG vaccination at site?

Parents need not worry, as this is a part of process of immunisation. Avoid using local antiseptic or any antibiotics for it. At most, clean it with sterile wet cotton, and that is enough. 

If ulcer is big or discharge is too much then seek advice of a paediatrician. 

How effective is BCG vaccine ?

BCG vaccine is primarily for prevention of severe tuberculosis, especially in kids who are less than 6 years old. Few examples of severe tuberculosis are TB meningitis ( tuberculosis of brain ) and disseminated tuberculosis ( tuberculosis spreading entire body ). 

It is 50-80% effective in averting these serious infections and their consequences. But when in comes to preventing TB of lungs and checking inter-personal spread of TB bacteria, BCG is not much of value. 

Important note : 

Here the goal BCG vaccine has served through years is to cut down morbidity and mortality related to grave infections of TB in young children. 

What are tuberculosis vaccine side effects?

BCG vaccine is very much safe. Common side effects like soreness and redness at site of injection are mild, and no need to worry about. Fever and headache ( in case of child ), can occur following BCG.

Other infrequent tuberculosis vaccine side effects are as following.

  1. Large sized ulcer 
  2. Excessive discharge with sinus at injection site
  3. Lymphadenitis- Swollen lymph glands on armpit and neck, or sometimes all over body.
  4. Abscess – Pus filled lesion in muscle, below site of injection 
  5. Osteitis/ Osteomyelitis- Infection of bone in the local area ( very rare )
  6. Disseminated BCG infection- BCG infection spreading to whole body ( This happens when immunity of individual is extremely poor ).
  7. Allergic reaction following BCG vaccination ( it is extremely unlikely )

If above mentioned side effects are there then take a doctor’s suggestion.

Compared to side effects, the benefits that BCG vaccine comes with are tremendous. This vaccine has been so far successful in remarkably reducing death and suffering due to TB. 


I have worked in remote areas where so many kids are still suffering from brain TB ( TB meningitis) and getting paralysed for life. Also many parents are losing their kids, simply due to ignorance about BCG vaccine for tuberculosis. 

If just 0.1 ml of a solution can save a kid’s life then, why not! If few words of insight can fight ignorance ,then why to shy away from spreading awareness.


All the informations provided here are for educational and awareness purpose only. Kindly do not use these as alternative to medical consultation.

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