Families in Samoa that are not vaccinated against measles have been told to display red flags outside their homes as part of a mass vaccination campaign against an epidemic that has killed at least 62 people.

Key points: Medical teams are going door-to-door administering vaccines

Medical teams are going door-to-door administering vaccines Businesses and Government services have been shut down for two days

Businesses and Government services have been shut down for two days Samoa's Prime Minister denied his Government was was too slow to respond to the outbreak

There are more than 4,200 reported cases of measles in the country, out of a total population of 200,000.

More than 150 mobile vaccination teams are going door-to-door, administering the MMR vaccine to households displaying the red flags, or any other red-coloured material.

The effort coincides with the first day of a 48-hour shutdown of businesses and Government services, which has left the roads of the capital Apia largely empty.

Authorities have urged people to stay home and limit non-essential travel.

There are currently 172 measles patients in the country's hospitals — among them are 19 critically-ill children and three pregnant women.

The flags are supposed to let the medical teams know which homes to visit. ( TV1 Samoa )

"Every child that arrives is well-known to people across the hospital, or to the community that's involved with their care," Abby Trewin from the Australian National Critical Care and Trauma Response Centre told the ABC.

Ms Trewin is part of an Australian team of healthcare practitioners who have been sent to Samoa to help fight the epidemic.

"It does have an emotional impact on staff, as well as other families around these sick children," she said.

At least one funeral home in the Pacific Island nation has run out of coffins for children, New Zealand media reported.

PM defends measles response

Prime Minister Tuilaepa Sailele denied his Government could have responded to the crisis sooner. ( Supplied: Government of Samoa )

The Government of Samoa has come under fire for its handling of the measles epidemic, amid accusations officials were too slow in responding to the initial outbreak.

Answering questions from reporters at a press conference, Samoan Prime Minister Tuilaepa Sailele rejected claims his Government could have handled the crisis better.

"The measles that we have caught came from a visitor from New Zealand, and so we did not leave it too late," he said.

Asked by a British journalist why Samoan authorities did not start a mass vaccination program months ago, Mr Sailele tried to change the subject to UK politics.

"What have you written about Brexit? … Before you talk about our problem, talk about your own problem," he said.

The Prime Minister also defended his Government's controversial decision to suspend measles vaccinations for several months last year, following the deaths of two children who were later found to have been administered the shots incorrectly.

A nurse had mixed the vaccine powder with an expired anaesthetic, killing the babies. The two nurses involved in the incident pleaded guilty to manslaughter and were subsequently jailed.

Mr Sailele said when the deaths happened, there were concerns about the safety of Samoa's vaccine stocks.

"Those two children died, at the same time, there was also suspicion, and not just in Samoa but also those overseas say in America, where a lot of people [were] questioning the vaccines we are using," he said.

"That is a very, very important consideration."