A man who was having a heart attack delayed going to hospital because he didn't want to be a burden on New Zealand's health system.

Within the same week, another patient who had a serious urine infection affecting their kidney put off getting help out of fear of catching Covid-19 - "by the time they turned up to ED they were very very sick and needed a lot more than antibiotics".

These are just some "extremely unfortunate" examples showing the impacts of the Covid-19 pandemic that top emergency doctor John Bonning has described to the Weekend Herald.

Bonning - who's also the president of the Australasian College for Emergency Medicine's - wanted to warn New Zealanders about the "serious catch-up" that was looming after lockdown's lifted and the urgent need to prepare.

"We are very worried about the people who are not seeking care, and/or are presenting late ... and we are holding our breath for what is coming once lockdown is lifted."

Bonning said there would be a massive catch-up - especially in four or five months when people started to develop complications from the elective care they haven't been able to get.

"One patient is having to wait a month to get a gallbladder removal and by then he could be facing serious complications.

"There will also be many patients who have delayed treatment that will become acutely unwell."

He wanted to encourage people who were seriously unwell to still come into hospital.

"For example, if appendicitis is left too long, the bowel perforates and that's way more complicated."

Bonning stressed he was not talking about people with a hurt knee or a bit of vomiting to rush back into hospital, but more the urgent cases like appendicitis, chest pain and heart attacks.

The Waikato doctor said urgent action was needed to prepare for this "massive challenge ahead of us".

"Now, we need the politicians, the health managers and us all to think about the recovery stage and business as usual, getting things back on track by starting to do elective surgeries and clinic appointments.

Act party leader David Seymour said he was hugely concerned about the lack of non-Covid treatment available and said it was going to cost people's lives.

"Mental health we already know is being impacted hugely, I've heard of several people already who have committed suicide during this lockdown due to stress."

Seymour said he had heard from dozens of people whose treatment had been delayed and were scared about the impact it could have on their health.

"There's a genuine fear among people that they don't want to be seen out breaking the rules so they're reluctant to leave their house - some people literally think you're not allowed to leave your home."

Act party leader David Seymour. (Photo / File)

The message he wanted to give New Zealanders was that Covid-19 was not the only health care issue we face today.

"If you have a health issue you should access help.

"It is simply a matter of prioritisation and we need to recognise that all deaths are equally tragic and we need to start thinking about how to make sure we have care for other problems as well as the problem that is hogging the headlines."

Director-General of Health Ashley Bloomfield said it was very important that people did not neglect potentially serious health conditions because of concerns around Covid-19.

"As an example, we are aware that emergency department presentations at Wellington Regional Hospital during the lockdown have dropped to an average 95 per day. For the same period last year, this was around 190 per day."

At level 3 non-acute (elective) services and procedures in hospitals will continue to be deferred.

Bloomfield would not comment further on this.

Director-General of Health Ashley Bloomfield. (Photo / File)

"Please – follow the usual mechanisms for help – contact your GP or call for an ambulance in an emergency," he said.

Health services continue to have capacity to provide advice. Healthline's normal line is 0800 611 116.

"Don't leave it too long to seek help. If you need medical attention for any health concern please seek help promptly."