Northland District Health Board chief executive Nick Chamberlain has been caught up in a nasty rumour spread by antivaxxers.
The rumour claims he had a severe heart attack following his third dose, or booster dose, of the Pfizer COVID-19 vaccine.
But Dr Chamberlain says he hasn't even had his booster jab and the rumour caused great stress for his friends and family.
"When I was first made aware of it was on Monday morning and one of my staff rang me to check I was OK - they'd had contact with someone from Australia who was in the antivax or vaccine-hesitant community," Dr Chamberlain told Newshub. "Apparently, the rumour was going around that I'd had a severe heart attack and was in critical care.
"[The rumour] was linked to me having the third dose of the COVID vaccine which I haven't had yet as the bookings aren't opening until tomorrow," he said on Thursday.
Dr Chamberlain said he wanted people to know the rumour was completely untrue.
"It is absolutely completely nonsense and I feel very well and I haven't had the third dose, and I certainly haven't been in primary care."
He said this was an example of how dangerous misinformation can be.
"At times, it does have personal costs… Some people believe these rumours and it's worrying that the message that gets out there is the vaccine isn't safe. I've had the first two doses, of course, and didn't even have a sore arm.
"It's such a strongly evidence-based vaccine. I just hope people contact other trusted sources other than social media and the antivax community if they are hesitant at all."
The Pfizer vaccine is one of the first widely used vaccines based on mRNA technology which has been in development for decades. Its efficacy has surpassed scientists' expectations and its safety has been proven through the hundreds and millions of doses administered throughout the world.
Experts have said there are no known means of the vaccine being able to cause long-term effects.
The Pfizer vaccine has been linked to extremely rare cases of heart inflammation but the benefits of the jab in preventing COVID-19 far outweigh the risk, the World Health Organization and regulators around the globe have said.
Vaccination not only significantly reduces the likelihood people will be infected with COVID-19 but also lowers the chance people will pass it onto someone else or fall seriously ill.