The Katikati Medical Centre shares some helpful advice plus clarifies medical certificate requirements.

Do not come to school or work if you have any of these symptoms: cough, runny nose, sore throat, shortness of breath, loss of smell or have a fever or have been in contact with a confirmed or suspect case of Covid-19.
Instead phone the medical centre and a doctor will phone you back to assess if they need to see you in person or can refer you to the lab to be swabbed.
This phone or in person consultation is free if it is related to the Covid pandemic.
While waiting for the result, stay home in isolation until you are clear of symptoms for 48 hours even if your result comes back as negative.
If your test is positive a member of the Public Health Unit will contact you.
Schools and work do not require a medical certificate for you to return to work if you are off due to Covid or cold or flu like symptoms.