The bungled injections were given to 221 children between January 2009 and April 2012 who were given a single jab instead of separate vaccinations at Cope Street Surgery.

They were supposed to protect them against diphtheria, hib, pertussis, polio, tetanus, and measles, mumps and rubella (MMR) and national guidance states they should be given separately to ensure maximum protection.

Speaking to the Chronicle, Rebecca Hirst, 34, whose daughter Poppi was wrongly vaccinated, said it should never have happened.

The mum-of-three, of George Street, Worsbrough Bridge, received a letter on Tuesday informing her of the mistake and offering re-vaccination.

"You put your trust in a doctor to do things right. It's disgusting what's happened and in my eyes it shows incompetence.

"She was given the injection when she started nursery at three years old and she's six next month. So for nearly three years she's been walking around and has not been immunised.

"It's a massive failure if anything else. I'm going to put a complaint in to the General Medical Council."

The mistake was brought to the attention of NHS Barnsley's public health team in April by a healthcare professional, a spokesman said.

Since then the trust has reviewed every child's medical records from the practice, looked at every vaccination they received and traced those children who left the practice or moved out of the area, she added.

• The Chronicle contacted Cope Street Surgery but staff declined to comment.