Health officials are investigating a private clinic that has been supplying single measles vaccinations in Swansea.
The Children's Immunisation Centre in Cheshire ran a clinic at the weekend giving single measles jabs to children.
Its website makes claims about the jab which are causing concern for health officials battling a measles epidemic which has risen to 886 cases.
The centre says it is simply supplying demand from parents worried about the triple vaccination or MMR jab.
Public Health Wales (PHW) has said 78 more cases had been reported since last Thursday with 80 hospitalised since the outbreak began last November.
The Children's Immunisation Centre website gives telephone numbers for clinics offering single measles jabs in England and in Swansea but also links to old newspaper stories suggesting an autism link to the MMR (measles, mumps and rubella) vaccine.
On another page the centre claims that "the single measles vaccination gives a higher level of protection against the disease at 97% after the first primary vaccination".
It had also initially claimed that the single vaccines were the only safe option to immunise people against measles - but it later removed the claim from the website.
The BBC Wales investigative programme Week In Week Out brought these claims to the attention of the Medicines and Healthcare Products Regulatory Authority (MRHA), which said that PHW had since written to the centre asking it to substantiate the claims on the website.
The company says its information on protection rates is based on what the manufacturers of the vaccine have told them.
The programme filmed inside the centre's clinics in Swansea and Manchester.
The company charges £110 for each single measles jab plus a £50 registration fee per patient and says they are simply offering patients an alternative to the triple MMR vaccine.
Spokesperson Zoe Miller said: "It's not about business at all. We're opening up more, we're going to open in Newcastle so what stops us opening in Swansea? That's going to be a permanent clinic there."
The centre says it is considering running another clinic in Swansea this weekend.
PHW is warning that with the outbreak showing no signs of ending it is essential that parents have their children immunised with the MMR vaccine, provided free by the NHS.
And officials are emphasising that there is no evidence to suggest that the single measles vaccine is any safer than the combined MMR.
Dr Marion Lyons, director of health protection at PHW, tells the programme: "Having developed a vaccine which is just as effective as singles used to be, and now available in one, I'd like to think parents can accept that's the right thing for their child.
"[It involves] two injections instead of six and longer protection against the three viruses. And sometimes choice doesn't make sense because it's neither good medicine and it's more painful."
The programme also hears from the mother of Gareth Colfer-Williams, 25, who had measles when found dead at his home in Port Tennant, Swansea, last Thursday.
He had underlying health problems but his mother, Angela Colfer, is angry that he was not diagnosed with measles until after his death despite him being seen by doctors hours before he died.
A post mortem examination is due to be held to determine the cause of his death. But his mother is taking legal advice and calling for an inquiry into the treatment he received.
Abertawe Bro Morgannwg Health Board says it cannot comment on the detail of Mr Colfer-Williams's case but it would thoroughly investigate any concerns the coroner may have.
It added that it can be difficult to diagnose measles because many of the symptoms are similar to other viral illnesses particularly in the early stages.