Dr Ashley Bloomfield has told the Health Select Committee the youngest confirmed case from this outbreak was aged under one year old.
Covid-19 Response Minister Chirs Hipkins said the Delta variant appeared to be infecting younger people at a greater rate than other variants.
He said contact tracers were finding people were at home, and following the rules, but there were some situations where people had made use of the 48 hours to return to their home after the lockdown began.
Meanwhile, there are 41 new cases of Covid-19 in the community today, a day after the country's lockdown was extended, taking the total number of community cases to 148
New Zealand is staying in alert level 4 lockdown until at least midnight on Friday, and Auckland until at least midnight on Tuesday.