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The ESR monitors "sentinel sites" across New Zealand for a weekly influenza surveillance report, and the latest shows marked falls in most categories.
The rate of disease was not quite back to below the baseline seasonal level, but was well below the average seasonal rate.
GP visits, GP influenza cases and emergency department visits all fell markedly in recent days, as did influenza-related hospital stays and cases.
While the number of people with influenza-like diseases is low, the number of people who actually do have the potentially fatal disease continued to be high, the report said.
"Over 50% of samples tested in GPs and over 40% of samples tested in hospitals are influenza positive, which is one of the highest positivity rates for this period in recent years."
Seven GP clinics in the SDHB region contribute to the ESR report.
SDHB public health physician Anura Jayasinghe said influenza-like illness rates for GP visits in the south had not decreased in the past week.
"However neither do they appear to be above what would normally be expected at this time of year.
"Overall levels for southern district for this year remain just above the seasonal baseline level and are in line with national data."
Dr Jayasinghe said the high positivity rate for test samples for influenza showed the virus was responsible for a significant proportion of people presenting with acute respiratory illness in the south.
"The best way to prevent spread of influenza is to get the annual influenza vaccination, to stay at home if you are unwell, wash hands regularly, don't share drinks, avoid crowded places and cover your mouth and nose with a tissue when you cough or sneeze."
New Zealand's relatively quiet flu season is in contrast to Australia, where influenza activity is increasing and is reported to be at a high level for this time of year in most states and territories.
A near record number of influenza vaccine doses were distributed in New Zealand this year and the Ministry of Health had to import extra supplies to meet demand.