Healthline staff have given help to 170,000 Kiwis since the Covid-19 outbreak hit the country in March.
That has led to the National Telehealth Service team some days receiving 10 times more calls than normal for this time of year, National Telehealth Service chief executive Andrew Slater said.
Between March 1 and March 24, there were 130,450 calls to Healthline numbers compared with 25,993 the previous year, data released to the Herald showed.
The huge volume of calls had led some people to spend hours on hold while others were disconnected as they tried unsuccessfully to get through to Healthline for medical advice.
One Herald reader said in mid-March they waited on hold to Healthline for three hours before hanging up.
Slater acknowledged the sheer volume had meant some people had waited longer than he'd have liked.
"That's why we're getting more people behind more phones."
Slater said the service had taken a series of steps in the past 10 days to reduce waiting times.
This included employing and training 600 extra people - including 100 new work-from-home staff - and setting up five new call centres for a total of eight in which staff maintain a safe physical distance.
"We've been working day and night with Spark to deliver a five-month technology project in just seven days," he said.
Most Kiwis who had called Healthline's Covid-19 helpline were seeking more information to help them understand the virus better, Slater said.
Others had called to check whether their current cold symptoms were Covid-19 symptoms or to seek advice on self-isolation for them or for recently returned or soon-to-arrive international travellers and family members.
Healthline's Covid-19 support line number at 0800 358 5453 was staffed by a team that included registered nurses and paramedics capable of providing health advice.
"It is important that people to call this number if they've been in contact with the virus have developed symptoms of fever, cough or shortness of breath," Slater said.