With spring just days away, the number of swine flu cases is on the way down, health officials say.

"DHBs report there has been less gridlock in hospitals than expected, and we hear there are fewer absences from schools and workplaces," said the deputy director of public health, Fran McGrath.

"People have really taken heed of the tried-and-true hygiene messages - cover coughs and sneezes, wash your hands often and stay home if you are sick," she said.

"These simple actions appear to have helped delay the spread of this virus and lessened the impact of this pandemic on our communities."

However, while the virus looked to be abating as the weather warmed up, Dr McGrath said it was unlikely to disappear completely .

She said the focus was now on being prepared for any increase in cases in the coming months, and ensuring health services could respond quickly if the virus became more widespread.

The latest Ministry of Health figures showed 16 people had died from swine flu in New Zealand while 10 people were in hospital with the virus, including six in intensive care.

In total, 3114 cases of swine flu have been confirmed, although the number of cases would be significantly higher as only a small proportion of people with symptoms were being tested, the ministry said.

Meanwhile, one of the first surveys to gather mortality data from across the globe shows more than half the deaths from swine flu have been among young adults.

The analysis of 574 pandemic deaths from 28 countries through mid-July found that being diabetic or obese significantly boosted the risk of dying.

Neither children nor the elderly are as vulnerable as initial reports indicated, found the study, published by Eurosurveillance, the monitoring arm of the European Centre for Disease Prevention and Control.

"Most deaths [51 per cent] occurred in the age group of 20- to 49-year-olds, but there is considerable variation depending on country or continent," the researchers reported.

Only 12 per cent of those who died were 60 or older.

These features - high mortality among young adults and the obese, but not the very young or elderly - are sharply different from the seasonal flu.

More than 90 per cent of deaths from seasonal flu, which kills 250,000 to 500,000 a year, are in people over 65.

Swine flu first erupted in Mexico in April and spread across the globe, infecting hundreds of thousands.