A call has been made for a review of how drugs are administered in the NHS following a series of hospital errors.
The baby was mistakenly given an MMR jab at a surgery in Edinburgh
A seven-week-old baby was given the MMR jab by mistake and two other patients were also given the wrong medication.
The SNP said that patient faith in the health service needed to be restored following the three cases.
However, Scotland's Chief Medical Officer said that of the 20 million dealings the NHS had with patients, only a tiny number had adverse results.
It has emerged that the child was taken to a doctor's surgery in Edinburgh for his diphtheria vaccination on 31 January but was instead given the measles, mumps and rubella jab.
GP Rosalind Wight, who works at the Durham Road Medical Group surgery, said she had apologised to the boy's foster parents and he was not harmed.
Scotland's Chief Medical Officer Dr Harry Burns moved to reassure patients.
He said: "The number of deaths occurring in surgical care has actually been falling progressively over the past few years.
"Although medicine has become more technical, it seems in many respects to be becoming safer.
"These dreadfully unfortunate cases that we've heard about are very rare."
The MMR vaccination is not normally given to children until they are about 12 months old.
In a statement, Dr Wight said: "We have apologised to the foster parents who brought the child to the surgery for the jab.
"The mistake was recognised straight away and the manufacturers were contacted.
"We were told the child's health would not be compromised and that additional treatment would not be necessary.
"The foster parents have since been back to the surgery where the child has been checked and is in good health."
The incident follows reports of a number of other cases of patients in Scotland being given the wrong treatment.
It has emerged that a woman died a day after mistakenly being given medicine intended for another patient at Glasgow's Stobhill Hospital in 2004.
Last week a teenage girl being treated for a brain tumour spoke out after she was given 17 overdoses of radiation at Scotland's largest cancer treatment centre, the Beatson in Glasgow.
The SNP's health spokeswoman Shona Robison said: "Obviously all of these cases are very concerning and show the clear need for more robust systems in place to minimise human error in the health service.
"All of the recent cases have happened as a result of patients being administered the wrong medicine.
"Patient safety is paramount, therefore it is vital that systems are reviewed to make them safer for patients, with more checks in place to ensure that such dangerous mistakes do not happen and public confidence is restored in the health service."
A Scottish Executive spokesperson said: "This is a regrettable incident, but it is a matter for the GP practice and for NHS Lothian.
"There are over 20 million patient contacts with the NHS each year.
"Only a tiny proportion of patients encounter serious problems, but it is important that when they do, the cases are thoroughly investigated."