BCG vaccine

The BCG or Bacillus Calmette-Guerin, vaccine provides protection against tuberculosis, which is also called TB.

What is Tuberculosis?

Tuberculosis (TB) is a serious infection which affects the lungs and other parts of the body, like, the bones, joints and kidneys.

A person infected with lung TB will experience chronic cough, chest pain, weakness, unexplained weight loss, fever and night sweats. The infected person may even spit blood while coughing.

How is tuberculosis spread?

TB is spread from person to person through air. When people with lung TB sneeze, cough or spit, the TB germs are expelled out in air. If non-infected people inhale even a few of these germs, they are likely to get infected.¹

About 1/3rd of the global population has latent TB, which means that they are infected by the bacteria but don’t yet have the disease and hence cannot pass it on to others. About 40% of the Indian population has latent TB rather than TB disease.10

What is the schedule for vaccination?

BCG vaccine is generally given to babies.? It is recommended to vaccinate babies with BCG vaccine immediately after he or she is born, when the baby is still in the hospital.? The vaccine can be given up to 5 years of age.³

What is the Tuberculin skin test?

Before getting immunized with BCG, it is important to get the Tuberculin skin test/ Mantoux test done, to know if a person has been already infected with or has active TB disease.4

This test will be carried out for those who are:

  • Six years or older
  • Child under 6 years of age who has stayed in a country with high rate of TB, for more than 3 months
  • Has had a close contact with a person infected with TB
  • Someone who’s immediate family members have had TB in the last 5 years

If the test results are positive, it is more likely that the person is infected with TB. In that case, he or she should not get the BCG vaccination as it would have no effect.


Are there any side effects?

Everyone who has had a BCG vaccination would develop a blister immediately after getting the injection. This is normal and nothing to be worried about.

Reaction after the BCG vaccine has been given:

Immediately after a child has received the vaccine, a small swelling may appear at the site of injection. This swelling will generally stay for about 6-8 hours. Post that, it usually disappears and the injection site looks normal.

About 6-8 weeks later, another small swelling may appear that will resemble a mosquito bite. This swelling usually grows bigger forming a nodule, eventually developing into an ulcer discharging some fluid. The ulcer then heals leaving behind a scar. It takes about 2-5 weeks for this entire process to occur. At times, the process of ulceration and healing recurs 2-3 times. Eventually, a wrinkled scar forms which will be present for life!

In case ulceration occurs within a week after the child has been vaccinated, it is recommended to consult a paediatrician, as it may be a sign of tuberculosis in the child.

Very rarely, some people may develop a skin rash after getting the BCG vaccine.

The extremely rare side effects of BCG vaccine are as follows:9

  • Swollen and painful glands in the neck or armpit
  • Very few babies may develop a TB-like infection, especially those with a weakened immune system (in 0.8% of cases)

What if a dose is missed?

Generally, it is recommended that a baby should be given the BCG vaccination at birth, before the baby is discharged from the hospital. However, in case of a missed vaccination, the baby can have it till his or her 5th birthday.¹¹


1 Microbiol Spectr. 2017 Jan;5(1).

2 Vaccine. 2017 Mar 15. pii: S0264-410X(17)30251-7.



5 Dan Med J. 2016 Nov;63(11). pii: B5304.

6 Indian J Pediatr. 1994 Sep-Oct;61(5):451-62.

7 Vaccine. 2017 Mar 15. pii: S0264-410X(17)30251-7.

8 Tuberculosis (Edinb). 2016 Dec;101:164-173.

9 Rev Inst Med Trop Sao Paulo. 2016 Nov 3;58:84.