The number of nurses getting swine flu last year was not significantly different to the general population, a major study for the Ministry of Health has found.
Nurses and doctors had a very slightly higher incidence of swine flu than other occupations but the difference was not statistically significant, the ESR study found.
The study involved taking blood samples over the summer from a representative group of 1696 people, including 540 health workers, to check how widespread exposure to last year’s pandemic H1N1 virus had been.
It found that 26.7 per cent of the community had been exposed but the seroprevalence rate differed widely with age and ethnicity.
The age range most likely to be exposed to the flu was school-aged children (five to 19 years), where just under half showed immunity, followed by preschool children at 29.5 per cent. The hardest hit section of the community was Pacific with almost half being exposed to the virus followed by Ma¯ori with 36.3 per cent.
The study said primary health care workers (29.6 per cent) and secondary health care workers (25.3 per cent) had “no significant difference in seroprevalence compared to the community participants”.
The New Zealand finding contrasted with a similar study in Taiwan which found a significant difference between front-line hospital workers and the general population.
The baseline samples indicated that nearly 12 per cent of the population (about 480,000 people) already had some immunity to H1N1 prior to last winter’s outbreak and this was most common in the over-60s.
Following the outbreak the study indicates that more than one in four New Zealanders had immunity to the virus, indicating that nearly 800,000 people were exposed to H1N1 over last year’s flu season.
ESR’s national influenza centre head, Dr Sue Huang said one of the study’s interesting findings was that about half of those whose blood tests were positive reported no symptoms and weren’t aware they had had the virus. “For most people their symptoms were mild, however, for many it was a very serious illness requiring an admission to intensive care,” Dr Huang said.
Huang said another surprising finding of the study was how many young people were effected with the high rate of transmission amongst school-aged children being about ten times higher than estimated.