The number of flu cases in New Zealand remains at an unseasonable low, leaving scientists pleased but slightly baffled as to why so few people have fallen foul of the annual winter disease.
The Institute of Environmental Science and Research (ESR) tracks New Zealand flu cases on a weekly basis, and for some time has been predicting peak flu season cannot be far off.
However, flu case statistics remain obstinately - and pleasingly - low, leaving doctors wondering if New Zealand is set to get off lightly this year.
''It is quite an unusual year,'' ESR strategic health intelligence manager Lisa Oakley said.
''We are debating among ourselves what might be causing that ... It's not a bad thing to be looking at.
''Flu is very tricky because the virus does change and strains do change every year, so we are always monitoring it very closely.''
This year's flu season was severe in the northern hemisphere, prompting New Zealand health officials to step up the annual campaign promoting the flu vaccine.
It was possible this had been a success and that vaccinations had resulted in fewer people infected, Dr Oakley said.
''It's not looking anything like the northern hemisphere. We did quite a bit of planning work with the Ministry of Health on this,'' she said.
''H1N1 is the predominant strain of flu this year and it may be that there is natural immunity out there as we have had H1N1 in years before.''
Newly released statistics for the week ended August 5 show GP visits with flu-like illnesses were down, but GP and emergency department visits were slightly up.
Intensive care admissions for flu were also up, but hospital stays, hospital influenza cases and ICU admissions for flu-like symptoms were all down.
However, all statistics were tracking well below the usual numbers for this time of year.
''We are just starting to see a bit more flu activity in the community now, but it is much, much lower than we would expect,'' Dr Oakley said.
''Sometimes you get a season which is a late starter, but it's not quite looking like that either at the moment.
''We think we might see a slight increase over the next few weeks, but we wouldn't expect it to increase to usual levels.''
