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BCG vaccine and TB in babies

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 3 minutes read

The BCG vaccine is designed to protect your child against catching a disease called tuberculosis (TB). TB is a bacterial infection that mainly affects the lungs, but the more severe form can also cause meningitis (swelling of the brain) in young children, and abscesses can form in the spine or other key organs and structures.

There were almost 8,000 new cases of TB reported in the US in 2021, but it’s more common in South East Asia and sub-Saharan Africa. TB is infectious and can spread by coming into contact with the infected droplets of another person – by them coughing, sneezing, or speaking while they have the so-called “active” form of the infection. The bacteria need a good bit of time and exposure to pass themselves on, so it’s usually transmitted through very close and prolonged contact, like in the workplace or living with someone infected.

The vaccine contains a weakened form of the bacteria that cannot cause the disease but will protect your baby if they ever come into contact with the disease. But it’s not routinely offered to every baby in the US; it depends on their individual risk of acquiring the disease.

What are the symptoms of TB?

TB in young babies can affect the lungs, causing a persistent cough lasting more than 2 weeks, but it can cause other symptoms like fatigue, fever, difficulty gaining weight, or even weight loss. If TB does occur, there is a medical treatment regimen that can cure the disease - it's a course of different antibiotics to be taken for 6 months. 

Should my baby be immunized?

In the US, the BCG vaccine is offered to babies deemed at higher risk of catching TB. This can be if they have a family member who comes from a country with high rates of TB, if they live in an area with high rates, or if they have close contact with someone who has a current or past TB infection. The vaccination is usually given just after birth or within the first month and injected into the upper outer arm.

Are there any side effects?

You'll likely see a raised blister at the injection site, soreness, and redness. Between 2 and 6 weeks later, a spot will appear that should slowly heal but may leave a small scar. You should contact your doctor for a review if there is any sign of infection.

When should my baby avoid the vaccine?

You should postpone your appointment if your baby is unwell with a fever at the time. Suppose your child has a weakened immune system due to severe medical illness or immune-suppressant medication. In that case, you should speak with your child's specialist, as the weakened bacteria in the vaccine could cause them a serious infection rather than the desired protection. But your specialist may suggest that the risk of severe illness if they caught TB would be worse.

As with any vaccine, it's up to you whether you take up the offer for your child to receive it. You may have further questions to ask of your doctor or practice nurse before coming to a decision. However, if your child or anyone else, including adults, has TB, it's a condition that, by law, requires you or your child to receive the full course of antibiotic treatment. It's known as a notifiable disease that doctors have to tell the US health authorities about.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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