BCG vaccine: does it hurt? See when to take, composition and effect

The meningitis tuberculosis is an extremely dangerous brain disease, as well as pulmonary tuberculosis is also.

One of the bacteria responsible for these infections is very contagious and, in addition to affecting the brain and lungs, it can cause problems in other parts of the body.

Fortunately, there is a vaccine that can protect the human body from this bacterium.

It is the BCG vaccine.

Read and learn more about this powerful weapon against Mycobacterium bacteria tuberculosis !


What is the BCG vaccine?

The BCG vaccine is used to guarantee immunity to tuberculous meningitis, caused by the bacterium Mycobacterium tuberculosis . However, it is not able to offer 100% effectiveness in preventing pulmonary tuberculosis .

Even so, the administration of the mass vaccine is important to prevent the most serious manifestations of the disease, such as tuberculous meningitis and miliary tuberculosis (widespread form).

It is mandatory and given to the newborn, reducing the chances of this extremely contagious and dangerous disease spreading.

It is produced from the attenuation of another extremely similar agent, Mycobacterium bovis , of bovine origin.

The attenuated version of M. bovis was acquired through the selection of weaker varieties in cultures of the bacterium. These chosen agents reproduced again and among the new culture, the weaker bacteria were selected again.

After a total of 231 generations over 13 years, in 1919, the weakened variety was named the bacillus Calmette-Guérin by the researchers who produced it, Jean Marie Camille Guérin and Albert León Charles Calmette.

Currently, the versions used in the vaccine are not exactly similar to the one produced in 1919, having some genetic variations according to the laboratory.

What is the BCG vaccine for?

The BCG vaccine serves to prevent the transmission of the bacterium Mycobacterium tuberculosis , one of the main causes of tuberculosis, a bacterial disease that normally affects the lungs.

This bacterium can also affect other parts of the body, such as bones or meninges (protective layers of the brain), thus causing meningitis instead of tuberculosis.

The vaccine protects against brain disease if it is due to Mycobacterium tuberculosis infection (remembering that several different bacteria can cause meningitis).

It is important to mention that the BCG vaccine is not particularly effective in protecting against the pulmonary form of the disease, but it is very effective in preventing tuberculous meningitis, which is a much more serious and emergency condition.

Group immunization

Group immunity, also called the herd effect, is one of the main benefits of the vaccine for a community when it comes to contagious diseases.

If a disease can be passed from person to person, having immunity does not just mean that you will not get the disease, but it also means that you will not pass it on to anyone.

Every vaccine has its contraindications, so some people cannot be vaccinated and immunized.

When most of a community is immune to a disease, even those people who cannot be immunized are protected, as no one around them can spread the infection.

This means that while not everyone in a group is immune, the group as a whole is. That is why it is very important that all those who can be vaccinated do so.

How does the BCG vaccine work in the body?

The BCG vaccine works by exposing the immune system to the bacillus Calmette-Guérin, which is an attenuated version of Mycobacterium bovis , which in turn is close to the main cause of tuberculosis and tuberculous meningitis in humans, Mycobacterium tuberculosis .

In this version, the bacterium is too weak to cause damage to the human body and the immune system is able to deal with it easily, thus acquiring immunity to the strong version of the pathogen and M. tuberculosis .

The BCG vaccine is only recommended for children under 1 year, as its effectiveness is reduced as the patient’s age increases and is not effective when applied to adults.

Read more: Minute Investigate: can having a vaccine cause autism?

When to get the BCG vaccine?

The BCG vaccine is routinely recommended from birth to 5 years of age. It is applied together with other vaccines in the maternity ward, but if this does not happen, at any time it is possible to visit a Basic Health Unit with the child so that they receive vaccination by SUS.

In addition, people of any age who live with diseases such as leprosy , unvaccinated foreigners or people who are leaving the country should receive it.

Is there an adequate age to get the BCG vaccine?

Yes , there is. The older the person, the less effective the vaccine is, and it is not considered effective when applied to adults.

It is recommended that the child receives the BCG vaccine before reaching 1 year of age.

How long does the BCG vaccine last?

It is estimated that the BCG vaccine provides protection that lasts for around 20 years, long enough for the body to develop and have stronger immunity. The vaccine is especially important for protecting children, who have weaker bodies, from meningitis.

Price: can you buy the BCG vaccine?

The BCG vaccine is available in hospitals and Basic Health Units (UBS), also found in private vaccination clinics.

You can receive free of charge through the Unified Health System (SUS), but also use private clinics. In such cases, the price can vary widely. An average value is between R $ 75 and R $ 90.

Does it have side effects?

The application of the BCG vaccine against tuberculosis can have some side effects. Are they:

Local reaction (inflamed area)

There is often a skin reaction at the injection site. A reddened swelling appears that slowly changes to a small wound, which eventually heals.


The wound caused by the reaction at the injection site can leave a scar. Many people believe that it is related to the effectiveness of immunization, which is a myth.

In fact, the scar indicates an immunological reaction, which is expected, but even when there are no marks, the vaccine is effective.

Read more: BCG vaccine is effective even in children without scarring, says WHO

Swollen lymph nodes

It is possible that, a few months after vaccination, the axillary lymph nodes (small organs that stay in the armpits and produce antibodies) may have swelling. This is temporary and is an immunological reaction to vaccination.

Suppurated lymph nodes

Very rarely, swollen lymph nodes may suppurate. This means that they may experience production of pus as a reaction to the vaccine.

Read more: BCG vaccine package insert

BCG vaccine contraindications

Although the vaccine is mandatory, there are some people who cannot get it. The main contraindications include newborns whose mother has been treated with medications that cause immunosuppression during pregnancy and premature babies who do not yet have 2 kg of weight. Understand more:

Immunocompromised children

The BCG vaccine is contraindicated for children with diseases that compromise immunity, such as genetics, or those who are HIV positive.

Since protection against infection depends on the immune reaction to the weakened bacteria, if the body’s defenses are compromised, the patient is left unprotected.

In such cases, there is even a danger of the organism being infected, even if the version of the bacteria used in the vaccine is extremely weakened, since without an efficient immune system, the agent is free to reproduce.

Where to find the BCG vaccine?

The BCG vaccine is indicated for children under 1 year of age and is usually administered in the hospital, shortly after birth. When delivery does not take place in the hospital, it is possible to get vaccination in units of the Unified Health System (SUS).

Just take your baby to a Basic Health Unit (UBS), also known as the Health Post, which provides free vaccination.

Common questions

Is the scar important?

No ! There is a myth that says that the vaccine only works on the child when it leaves that characteristic scar on the arm, and that when there is no such mark, the immunization must be reapplied. This is not true.

A study by the World Health Organization (WHO) has shown that, even in cases where the scar does not form, the child is still immunized. The brand has nothing to do with the effectiveness of the vaccine.

Does the Ministry of Health recommend getting vaccinated more than once?

No ! There is no benefit in the repetition of the BCG vaccine against tuberculosis. It is most effective when applied to newborns and is indicated for children up to one year old. Revaccination is not effective and does not increase immunity.

This also applies to cases where there is no scar formation after the vaccine.

Can the BCG vaccine be administered with other vaccines?

YEAH ! Several vaccines can be applied in conjunction with BCG to ensure immunity to various diseases. The vaccine against measles , polio , hepatitis B , yellow fever , among others, can be administered together.

Is there a drug interaction with the BCG vaccine?

No . Since the BCG vaccine is the application of a weakened bacterium and not a drug, there is no drug interaction .

Does BGC vaccine hurt?

Like every injection, the prick can cause discomfort in the baby. The pain, however, is rapid and there is no need for concern.

Does the BGC vaccine give you a fever?

Usually the BCG vaccine does not cause fever or malaise. The only care that may be needed is to thoroughly clean the area of ​​the arm where it was applied, especially if there is a skin reaction.

Until when to get the BCG vaccine?

It is recommended to take the vaccine before the child is one year old, however, it is possible to take it after that age as well. Talk to healthcare professionals to assess specific cases.