A vaccine mix-up landed a woman in great jeopardy. A perfectly healthy 30-year-old woman who went to a clinic in Ireland to receive a measles, mumps and rubella (MMR) shot, got infected with tuberculosis, all because a doctor mistakenly injected her with a BCG vaccine and in the wrong location, which allowed the bacteria to spread rapidly. The predicament of the woman was detailed in the American Journal of Case Reports.

The woman hoping to get a Measles shot instead received the Bacillus Calmette-Guérin (BCG) vaccine from an erring medic, who mixed up vaccines and ended up infecting the patient with the world's most deadly disease.

BCG vaccine is usually given to babies and young children, typically to protect them against getting TB.
The sight of the infection makes all the difference. Babies are injected with a weakened form of Mycobacterium bovis, the bacteria that causes tuberculosis, diluted in saline under the skin of the upper arm.

But since the medic believed it was actually an MMR jab, they injected it into the muscle of her arm. However, the BCG vaccine contains bacteria, unlike MMR shot that have viruses. Injecting the jab into the muscle allowed the bacteria to spread rapidly. Instead of protection against Measles, the woman ended up getting infected by TB.

Symptoms
The woman soon developed an oozing boil at the injection site battled the infection for months before it was finally diagnosed and treated.

"She mistakenly received the BCG vaccine intramuscularly in her left deltoid, and this error went unnoticed," the case report authors wrote. "One week later, she started to developed pain, swelling, and redness at the injection site on her shoulder," they continued

The diagnosisIt didn't come easily as the error wasn't detected initially. Doctors thought it was a bacterial skin infection called cellulitis at first which affected the deeper layers of the skin. She was given a seven day course of antibiotics, however, her symptoms persisted and that's when an MRI scan was done that showed a lesion in her arm muscle.

Another scan post two weeks showed that the lesion had swelled to an abscess and was filled with 15ml of fluid.

The doctors then extracted samples from the lesion, trying to understand what it was. The woman's shoulder then started to ooze "yellow, purulent discharge".

Tests of the pus came positive for Mycobacterium tuberculosis and it was concluded that the woman was battling a TB infection. A chest X-ray confirmed that her lungs were unaffected by the infection and no further lesions were found.