One-in-three New Zealand children had swine flu, study shows

Jun 4, 2010, 7:23 GMT

Wellington - One-in-three New Zealand schoolchildren contracted swine flu last year, but almost half of those infected showed no obvious symptoms, the Ministry of Health said Friday, reporting the results of a scientific study.

The finding surprised health officials with Dr Sue Huang, head of the national influenza centre, saying the rate of transmission and infection was about 10 times higher than originally estimated.

The study analysed blood tests on a number of volunteers, which Huang said confirmed that the illness spread rapidly through communities but nearly half of those affected showed no symptoms.

'For most people, their symptoms were mild,' Huang said. 'However, for many, it was a very serious illness requiring an admission to intensive care.'

The ministry said 35 deaths had been attributed to pandemic influenza and more than 1,000 people needed to be hospitalized for it last year.

The study found that nearly a third of New Zealanders were immune to swine flu because they had already had it by March before the country went into the Southern Hemisphere winter.

Many more had been immunized against it since, but the Deputy Director of Public Health, Dr Darren Hunt, said a large proportion of the population remained vulnerable. He said there had been 12 confirmed cases this year

The World Health Organization reported this week that the most active areas of pandemic virus transmission were in parts of the Caribbean and South-East Asia where low-level circulation was occurring. There was little evidence of pandemic influenza activity in the temperate zone of the Southern Hemisphere as it moves into winter.