Delegates who attended the World Hereford Conference in Queenstown earlier this month are now being asked to self-isolate after two of the new COVID-19 cases confirmed in New Zealand today were revealed to have attended that event.

The conference was held between March 9 and 13, featuring attendees from throughout New Zealand and the world. Four attendees have tested positive - two New Zealanders, one in Uruguay and one in Australia.

Director-general of health Dr Ashley Bloomfield announced 14 new cases confirmed by laboratory test today, bringing the total number of COVID-19 cases confirmed in New Zealand to 66 plus four probably cases.

Just over 1200 tests were carried out yesterday, bringing the total number of tests to date to around 6000.

The new cases are in Auckland (5), Northland (1), Canterbury (1), New Plymouth (2),Hamilton (1), Tauranga (1), Coromandel (1), Dunedin (1).

Of those, he said 11 had a history of international travel, one was a close contact of a confirmed case and two had attended the World Hereford Conference.

"Close contacts of those cases are being asked to self-isolate and other attendees at the conference are now considered as close contacts, in a precautionary way, and they have also been contacted and asked to self-isolate for 14 days since they were in contact with people who were at that conference," Dr Bloomfield said.

The Southern District Health Board is doing the tracking and tracing work on this, with support from the Ministry of Health.

Meanwhile, Dr Bloomfield also issued a plea to the over 70s to stay at home. He said that while he recognised many were fit and healthy and leading active lives, the older people got the less their immune system was able to fight this virus. Overseas experience showed that older people were at more risk of serious complications from COVID-19.

"Please do heed the advice to stay at home. Ask friends and family, particularly children, not to visit. For the meantime this may mean talking to your family on Skype or some other method," he said.

He also urged people to call the Healthline number only if they required medical advice. General information about COVID-19 or self-isolation was available on the official COVID-19 website. The service had sufficient capacity if people just used it as intended, to check on symptoms, he said.