Fifteen people have been hospitalised and quarantined with "norovirus-like symptoms" after attending the annual Rhythm and Vines music festival.
Hauora Tairawhiti - previously the Tairawhiti District Health Board - says the group were admitted to Gisborne Hospital early on Monday morning suffering from diarrhoea and vomiting.
"The number of people presenting with norovirus-like symptoms meant people need to be isolated to avoid contamination," Medical Officer of Health Bruce Duncan said.
"Fifteen young people were transported to Gisborne Hospital where an isolation ward has been set up. The priority is avoiding an outbreak."
He said with thousands in close proximity at the festival, preventing a mass outbreak had been top priority.
"At this stage, this appears to have been successful," he said.
"Norovirus has not been confirmed, but it remains a possibility."
About 20,000 people attended the New Year festival at Waiohika Estate, now in its 15th year, including Prime Minister Jacinda Ardern.
Those leaving on Monday morning were asked if they had been experiencing vomiting and diarrhoea during breath testing, Dr Duncan said.
The health board says anyone who falls ill needs to contact Healthline for advice, drink plenty of water and make sure they wash their hands before handling food and after going to the toilet.
Symptoms usually last up to three days.