Hospital staff are the latest group to be targeted for immunisation against measles in the Swansea epidemic.
Clinics will be open at all health units to ensure staff are protected and do not catch or pass the disease on.
More than 800 cases of measles have been reported in the outbreak but new figures later are expected to show yet another increase.
Tests will investigate whether a man found dead at his home in Swansea died from measles or other causes.
Gareth Colfer-Williams, 25, was known to have other health problems including asthma.
Since the outbreak began in November, 77 people have needed hospital treatment for the illness.
As health workers are in the front line of the efforts to control the outbreak, they could be considered at greater risk of meeting people either suffering with the disease or incubating it.
Immunisation clinics are being run from 08:00 BST to 20:00 BST to ensure all staff are immunised, particularly those in children’s units.
Abertawe Bro Morgannwg University Health Board has announced that 10 schools in Swansea and Neath Port Talbot are to be visited this week with the MMR jab being offered to more than 1,700 pupils.
Measures are also being taken in many other health authority areas around Wales.
Hywel Dda health board serving mid and west Wales has announced plans to offer MMR jabs to all children and young people at secondary schools in Carmarthenshire, Ceredigion and Pembrokeshire from next Monday.
School clinics will also be held at all comprehensive schools in Powys.
Vaccination drop-in sessions will also be held at the Elizabeth Williams Clinic, Llanelli, on Saturday.