A European wide shortage of the BCG vaccine has led to a delay for Mayo children due to get the jab.
HSE West told parents across Mayo last week that the BCG vaccine is not available at this time.
The health authority has now advised there is a European shortage of the vaccine, caused by a problem with the supplier.
The BCG vaccine immunises children against tuberculosis (TB).
HSE West is advising that parents will be notified as soon as the vaccine becomes available again.
However, it will be late July before the vaccine is available again and priority will then be given to the neonatal BCG programme so it will be offered to newborns and those at greatest risk first.