More than 2,000 people were vaccinated on Saturday at clinics set up to tackle a measles epidemic in south Wales.
Queues of people turned up early at many of the special drop-in sessions to receive their free MMR jabs.
Health officials said over 1,700 jabs were administered in the Abertawe Bro Morgannwg University Health Board area, which includes Swansea, Neath Port Talbot and Bridgend.
In south east Wales a further 400 people received the vaccine in Ystrad Mynach, near Caerphilly, and 200 people had the MMR injection in Newport.
Further clinics are expected to be held next weekend and schools are also being targeted next week as officials try and prevent the epidemic spreading further.
In Swansea, more nearly 700 people have been infected and at least 6,000 children remain unvaccinated in the south west Wales county.
Meanwhile, the Government dismissed claims by Dr Andrew Wakefield - the doctor who sparked a global scare about the MMR vaccine 15 years ago - that officials were responsible for the recent outbreak affecting south Wales, the north east of England and in Gloucestershire.
Dr Wakefield, who was struck off over the MMR controversy, said officials had appeared to be more concerned about protecting the MMR programme than they were about protecting children when they withdrew the option of single measles vaccine.
"These government officials put price before children's health and have been seeking to cover up this shameful fact ever since," he added.
A Department of Health spokesman said: "Dr Andrew Wakefield's claims are completely incorrect.
"Immunisation advice from the department has always kept the interests of patients paramount. Measles is a highly infectious and harmful disease.
"If your child has not had two doses of MMR, whatever their age, we urge you to contact your GP surgery and make an appointment."
Professor David Salisbury, director of immunisation at the Department of Health, said the problems in Wales were "historic".
"Our immunisation coverage rates, currently, are extremely high, 95% of children are being vaccinated in this country," he told BBC Breakfast.
Asked about the situation in Wales, he said: "That is a historic problem, the legacy of bizarre suggestions about vaccines and autism from 15 years ago, that's not the situation currently."
Although the outbreak is centred on Swansea, cases have continued to be reported across the principality.
Most are in the Abertawe Bro Morgannwg University Heath Board area.
The board's director of public health, Dr Sara Hayes, said: "We are very pleased so many people turned up today and I'd like to thank everyone for their patience whilst they waited to be seen.
"I cannot stress enough how important it is for people to have their MMR. The number of cases and people being hospitalised with measles is continuing to rise and we can only stop it by protecting those we can against it.
"Measles is a horrible disease and can have long term effects such as deafness and blindness.
"This is why we are offering first vaccinations early to babies aged six months to one year.
"It's also very important for older children and adults born after 1970 to make sure they have had two MMRs."
Cases have also been found in Powys and in the Hywel Dda Health Board area - which covers Carmarthenshire, Ceredigion and Pembrokeshire.
Typical symptoms of measles include fever, cough, conjunctivitis and a rash. Complications are quite common even in healthy people, and about 20% of reported measles cases experience one or more complications.
These can include ear infections, vomiting and diarrhoea, pneumonia, meningitis and serious eye disorders.
Before the introduction of the MMR jab in 1988, about half a million children caught measles each year in the UK.
Approximately 100 of those died.
However, concerns over the jab's safety were raised in the late 1990s when Dr Wakefield produced a since discredited paper suggesting MMR was linked to an increased risk of autism.