"Once it gets into the Waikato, from a practical point of view and I'm certainly no expert, but you've simply just got to look at the geography and the number of roads radiating out from the Waikato it's not as easy as blocking off Auckland.
"So practically, I don't know if it's going to be possible, but we've got to try and contain it because there's still a lot of people out there that aren't vaccinated and we're still likely to overwhelm our health services," he told the Herald on Wednesday.
Mylchreest last night said he did not call for an entire North Island lockdown.
"You can read for yourself in the article, I stated the difficulty in how boundaries would be managed around the wider Waikato region if there was a level change to alert level 3," Mylchreest said.
Mylchreest said he has received immense public backlash.
"I have had horrific comments emailed to me, and I have seen the backlash on social media and it is not on," he said.
"We are people too and we are working hard to ensure the community is informed."
Mylchreest said this can only be done with correct and official information from the Ministry of Heath.
"We need to be working together, staying calm and ensuring that we are doing the best for our community – and at this stage, that is encouraging our community to follow Covid protocols and get vaccinated."
Director of public health Dr Caroline McElnay yesterday announced 39 new cases of Covid-19; 30 in Auckland but nine in Waikato, including cases in Kawhia and Karapiro.