NHS Highland has warned of delays affecting some child flu vaccinations in its area.
A UK-wide delay in the delivery of the nasal spray Fluenz Tetra has meant the health board receiving fewer vaccines than it ordered.
NHS Highland said deliveries UK-wide were between two to four weeks behind schedule.
It said primary school vaccination sessions due to start on 11 and 18 November had been postponed.
NHS Highland said the vaccine it did have available would be used for those most at risk of the complications from flu.
A spokesman said: "We are working hard to arrange further opportunities for vaccination for all the children affected. We will write to parents when the national supply issue is resolved and the alternative arrangements are confirmed.
"In the meantime any child flu vaccines which are available nationally and locally will be prioritised for use in pre-school children aged two to five years old and those school children aged five to 18 years with underlying health conditions.
"These children are at greatest risk from complications of the flu virus."
The health board said it appreciated the situation was "very challenging" for all involved and apologised for any inconvenience caused.
The spokesman added: "Our priority is to protect as many children as possible from the effects of flu and help reduce its spread in the community to other vulnerable individuals.
"We are extremely grateful for the understanding and cooperation from parents."