That email said the school expects that if anyone is self-isolating, any Whangaparaoa College students in the same household would also do so for 14 days.
"Please let us know if this applies to your household and we will arrange schoolwork for your child, as we believe it is best if they do not come to school."
In his email, Thomas attached a letter from the Auckland Regional Public Health Service which said the staff member was being monitored.
"They are staying home as a precaution, in case they develop the disease in the future. Please understand that people are not considered at risk if they have been close to a contact – as the contact does not have the disease.
"Contacts of contacts do not have to take any action such as isolating themselves or staying away from school.
"There will be high levels of anxiety amongst parents and students, and there will be commentary in social and other media.
"Please explain to your children that the staff member does not currently have Covid-19, and that they have not exposed anyone else to this virus."
Thomas told the Herald the school had already made some changes that were in "keeping with the spirit of the Prime Minister's request".
An example was that assemblies had been cancelled, he said.
The school show and the school's Polyfest showcase were both postponed, he said.
"Our staff and kids have put so much effort into them.
"The parents want to see them performing.
"So that opportunity will happen at some later stage."
Eight new cases of coronavirus have been confirmed today, with the patients returning to New Zealand on flights from Europe, Sydney, the Gold Coast and London.