With swine flu cases soaring in New Zealand and schools resuming tomorrow, health officials are advising teachers and students to stay home if they are sick.

In New Zealand there are now 2255 confirmed cases of swine flu (Influenza A H1N1) and the virus has led to the deaths of 10 people.

However, the actual number of people with swine flu was significantly higher because only a small proportion of people were being tested, the Ministry of Health said. This was because it was a mild illness for most people and they could recover at home without needing medical treatment.

Thousands of teachers and students were due to go back to school tomorrow with the end of the school holidays.

"If you have flu-like symptoms, stay at home until you are essentially well," Public Health director Dr Mark Jacobs said.

Anyone with flu symptoms should call their GP or Healthline on 0800 611 116.