"After numerous attempts, we have been unable to connect with the Ministry of Health to confirm the discrepancies in the time of the exposure event and classification of contacts."
She said this was disappointing to the organisation and its members.
"Naming our Fraser Cove club as a location of interest with close contacts prior to any risk assessment being completed is inconsistent with our past experience and with the advice and guidelines on the Ministry of Health's website."
The website stated that those within gym settings were classified as a close contact if "you have spent time in an indoor space for more than one hour with a positive case".
In her view: "As the average person spends less than an hour exercising, the classification of all people within the facility for a two-hour period as close contacts is clearly in error.
"It is likely forcing over 100 people and their secondary contacts into self-isolation unnecessarily."
She said the business would continue to chase clarification, but was asking affected staff and members to isolate in the meantime.
The Fraser Cove gym would remain open with help from Hamilton staff, she said.
"We continue to manage capacity limits within the club and viral disinfecting has been a daily procedure since the beginning of the pandemic.
"We have the access control and CCTV systems to accurately classify contacts and have worked with other DHBs to do so in previous exposure events," she said.
"We believe everyone is doing their best to manage through the pandemic and mistakes will happen, however, these mistakes have drastic consequences and need to be rectified."
A ministry spokesperson said health officials had added measures to slow the spread of Omicron in recognition of its increased infectiousness.
"Out of an abundance of caution, some locations of interest are being treated as close contact exposure events, where they may have previously been treated as casual contact exposure events.
"Local public health units assess exposure events on a case-by-case basis, taking into account factors that will vary with each event.
"These could include the number of people, the management of entrances and exits, the separation between different spaces, the extent to which people were mixing and what infection prevention controls were in place."
The spokesperson said while guidance for managing exposure events was issued by the Ministry, including for gyms, the management was completed by public health officials.
"Determining the health advice for a particular exposure event is ultimately their decision."
Contact tracers "work at pace" and the pressing need to carry out case interviews, identify and contact close contacts, assess exposure events meant businesses were not always told before a location of interest was published, the spokesperson said.
"We acknowledge that this can be stressful for some people, however, it's important that action is taken quickly. It's measures like these that will protect New Zealand from the most severe outcomes of the Omicron variant.'
De Wet said Toi Te Ora Public Health had been working with the management team of City Fitness Gym.
He said the risk assessment took into account a number of factors including how easily the Omicron variant of Covid-19 might be transmitted in the gym environment and the current phase of the Omicron strategy which aimed to stamp out any local transmission.
"Based on the case investigation, the exposure event timeframes have been confirmed and all gym members and others who were on the gym floor in this time period are considered to be close contacts."
However, he said through further risk assessment work, they had been able to reclassify most staff on the premises at the time but not on the gym floor as casual contacts rather than close contacts.
"We acknowledge the disruption that this can have on those involved and thank everyone for their commitment to helping protect our communities, slow the spread of the virus and allow more people more time to be vaccinated and boosted before Omicron transmission is more widespread in New Zealand.
"At this phase of the Omicron response every day counts. Every day we are able to prevent transmission in our communities allows tens of thousands more people to be vaccinated and boosted before we have widespread transmission in New Zealand."
Bay of Plenty District Health Board's community-based testing lead Aroha Tito said: "Anyone who has been at a location of interest at the times notified should follow the Ministry of Health's guidance on testing and isolation.
"We also urge anyone who has symptoms to seek a test. There is sufficient, existing capacity across the Bay of Plenty to test for Covid-19. Your nearest testing site can be found online at Healthpoint," Tito said.
ExerciseNZ chief executive Richard Beddie called for "consistency" from all district health boards to avoid unnecessary costs and disruptions for gym members and staff.
"Some DHBs are classing close contacts in gym settings while others are not following the Covid rules as set by the Ministry of Health," he said in a written statement.
He said gyms had a lot of technology to help with contact tracing and often had member photos on file, which could help identify close contacts.
"This is far more effective than a blanket approach of posting on the national Covid website 'everyone who visited should stay at home'," he said.
