Many people will be fearful of deeply private information being shared, after a health agency's systems were hacked, a patient advocate says.
Wellington Primary Health Organisation Tū Ora Compass Health yesterday reported its systems have been breached by cyber attacks multiple times since 2016.
It holds data about the medical tests and treatments of about one million people from the Wellington, Wairarapa and Manawatū region.
Mark Fisher, the head of HIV and AIDS support group Body Positive, said there are good reasons people might keep their health status secret.
In the past Body Positive members have lost jobs, housing, friendships and family relationships when people have learned they have the virus.
He said patients with many different health conditions could face fallout if their private information was shared.
"There can be significant harm to their health and wellbeing, and mental health. It's very upsetting."
The PHO said it's not yet known if any patient information was accessed and that may never be known. Patient notes held by GPs are not at risk.
But information the PHO holds includes details about addresses, vaccinations, medical tests, treatments, diabetes checks and cervical screening.
The Ministry of Health has asked all DHBs and primary health organisations to confirm their systems are secure ahead of further independent reviews.
The Medical Association also said health providers will be rigorously checking their security systems after news of the cyber hack.
Kate Braddock, chair of the association, said health organisations take patient privacy and security extremely seriously.
"I am sure that all the PHOs are doing their very best to ensure that any potential unauthorised access is dealt with."