Drop-in clinics offering MMR jabs are being held at hospitals in Swansea, Neath Port Talbot and Bridgend, where the measles epidemic is at its height.
They are part of the health authorities' attempt to contain the outbreak, which began last November.
More than 1,200 people across Wales have now contracted measles.
Public Health Wales director Sarah Hayes said she hope people would continue to come forward, although the epidemic appears to have peaked.
In the latest figures released by Public Health Wales on Friday, the number of confirmed cases of the disease in the measles area rose by 13 to a total of 1,074.
The health board said it had huge concern about the cases in the former county of Gwent, where almost 10,000 children are still to receive the triple vaccination against measles, mumps and rubella.
Speaking on BBC Radio Wales' Good Morning Wales, Dr Hayes said they were very pleased how the clinics run on many Saturdays over the past six weeks have gone.
"We're getting twice as many people as we originally expected every time and the attendance just seems to be going up each time we hold them," she said.
"We hope that people still keep coming because while its true that we seem to be past the peak we are really worried that measles is circulating and if we don't keep going it will just carry on rumbling around."
But she added that the target for the authorities remained to vaccinate as many children aged between 10 and 18 as possible.
"That's our real focus because they're the people that have had the highest attack rate," Dr Hayes explained.
"But we are pleased when anyone comes up who isn't clear whether they've had an MMR before or measles before because we're just so keen that everybody gets protected. And the drop-in clinic gives whole families the opportunity to get covered."
The regular weekend drop-in clinics were not held over the bank holiday weekend but have returned on Saturday between 10:00 and 16:00 BST.
Vaccination teams will also be going into Gorseinon College's Gower and Tycoch campuses on Tuesday and Wednesday. They will be at Neath Port Talbot college's Neath and Afan campuses on Thursday and Friday.
Bridgend College will be visited over two days in the following week with details to be confirmed later.
Dr Hayes said people should just turn up for the drop-in clinics at hospitals on Saturday.
"The first few weeks we run them, we had queues developing. But even then the queue was about an hour and a half, two hours tops and many areas haven't had queues.
"The last time we ran one of these clinics, the queuing was much much less because they're getting much slicker, they're getting through the numbers."