BCG vaccine reactions

As I was bathing our almost-10week old daughter one evening I saw a raised red spot on her upper right arm. It was about 1cm across and looked like an angry pimple. Is this an insect bite? An infection? No, I quickly realised, this is a very common reaction to the BCG vaccination our daughter received just after birth.

The Bacille Calmette-Guérin (BCG) vaccination has been given for more than 90years world-wide (and since 1973 in South Africa). It contains a weakened strain of Mycobacterium Bovis that prepares the immune system against Mycobacterium Tuberculosis. TB is a very real risk in South Africa, especially for children under 5years of age, and HIV positive patients. While the immunization does not protect you 100% against lung-TB, it does prevent the more serious brain and bone versions of TB. This protective effect lasts for 15-20 years.

I have seen many moms ask advice on mom-groups when this red dot appears on their children’s arms. It is sneaky as it usually only becomes visible as a raised red spot between 2-6weeks, and even up to 12weeks after receiving the immunisation. It can then form a blister with a mild discharge and leaves a small scar. This is a very common side effect that affects almost 80% of babies and is due to the immune system activating against the Mycobacterium, so you do not have to worry. There can also be swelling of the lymph nodes on the same side (up to 1cm in size is still normal).

Our daughter’s BCG reaction

Laughter is the only medicine, without side effects.

Shannon L Alder

The vaccine is always given on the right upper arm, and is injected into the skin to decrease the risk of side effects. Only one dose is necessary and is usually given just after birth to ensure a wide coverage. If this dose was missed it can still be given safely up to 1year of age.

Serious side effects are luckily very rare and are mostly found in babies with HIV or another form of immune-deficiency. Due to this risk the WHO advised that babies that is known to be HIV positive should not receive this vaccination.  Serious side effects can include local abscesses or lymph node infection, infection of the bone (BCG-osteitis) or more distant lymph nodes/organs (disseminated BCG disease). This can be treated with TB-medication. As with all vaccinations there is a very small risk that your baby can have an acute allergic reaction, but all staff that gives vaccinations is trained to manage this complication.

So what should you do when you see this reaction in your baby?

  • Do not panic. This is a very common reaction and should not cause your baby too much discomfort.
  • Clean the spot/blister with water while bathing your baby and then cover it with a piece of gauze. Do not put a plaster directly on the area as it is better if it can dry out.
  • If your baby shows signs of pain when you handle the arm you can give one dose of Panado, if it does not improve rather see your doctor.
  • DO NOT apply any lotions, DO NOT open the blister / drain the “pimple”, this increases the risk for secondary infections that will leave a worse scar.

In peace I will lie down and sleep, for you alone, Lord, make me dwell in safety.

Psalm 4:8

There has been a lot of talk about the possibility that the BCG vaccine can prevent serious disease and deaths in the COVID 19 pandemic. The BCG vaccine seems to “train” the immune system by inducing metabolic and epigenetic changes which in turn protects you against severe illnesses caused by other viruses. It has been proven that the introduction of the BCG vaccine has decreased neonatal deaths related to sepsis, and decreased respiratory infections in adolescents.  There are currently many ongoing studies to see if it can be used in healthcare workers and other high risk individuals to assist in the fight against COVID 19. Until we see results from these studies we cannot use it for this reason, but we can be hopeful that this is an added benefit for the babies that does receive it!

I hope this can decrease any worries you might have had. Please share with your friends with small babies!


  1. Luca S, Mihaescu T; History of BCG Vaccine; Maedica (Buchar) 2013 Mar, 8(1): 53-58
  3. Venkataraman A, Yusuff M, Liebeschuetz S, Riddel A, Prendergast AJ; Management and outcome of Bacille Calmette-Guerin vaccine adverse reactions; Vaccine. 2015 Oct 5; 33(41): 5470–5474.
  5. Photo by Meghan Thompson on Unsplash

3 thoughts on “BCG vaccine reactions

  1. Do you have any thoughts on the “Vaxxed” movies?
    I know the anti vaccine movement have have been getting a lot of bad press but don’t you think some of the medical professionals/experts that they have onboard do have some valid points or reason for concern? Link in case you missed it:


  2. Hi Nické!!

    Dankie, ek het onthou jy het iets hieroor geskryf, want Petri se merk is baie groot en lyk of dit lelike litteken gaan maak…

    Hy is nou al 4 maande… Kan ek nogsteeds niks aansmeer of liggies masseer nie?

    Groete San


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s