A regional public health service is reassuring a school community after a parent of two of their students was diagnosed with coronavirus.

A woman has been announced as the second Kiwi case of Covid-19, her two children attend Westlake Girls and Westlake Boys high schools.

A letter from Auckland Regional Public Health Service to parents of the North Shore high schools confirmed the diagnosis and reassured families.

"While this is concerning for everyone, there is no risk to students, staff or others at the schools."

The letter stated the two children were not contagious and the parents hadn't been to the school since arriving back in New Zealand from northern Italy.

"The children are completely well and displaying no symptoms. They are now staying home as a precaution, in case they develop the disease in the future."

While acknowledging there may be "high levels of anxiety amongst parents and students", the letter stated the facts how the virus could be spread.

"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."

Families were warned about the negative impacts that could occur from posting information on social media

"Please explain to your children that the students do not have Covid-19, and that they have not exposed anyone else to this virus. Please ask them not to post any information on social media as this could lead to bullying."

• Second coronavirus case: Woman flew domestic flight, schools alerted

There are currently 74 countries with confirmed cases of coronavirus - the worst-hit countries are China with 80,000 cases, ranging down to Republic of Korea, Iran, then Italy with just over 2000 cases.