Flu epidemic fears talked down
The head of the country's national influenza centre is downplaying concerns the country could be hit by a swine flu-like epidemic this winter.
In the past week some media have carried stories saying experts believed the country could face an epidemic as big as swine flu as the virus spreads north from hard-hit Christchurch.
But Dr Sue Huang, an ESR virologist and director of the national centre, said the country was tracking within range of a typical flu season.
She did not believe this year's influenza activity would reach an epidemic as big as swine flu in 2009, as had been claimed.
The current viruses did not appear to be anything extraordinary and had not changed as much as the swine flu did.
Canterbury Health Laboratories virologist Dr Lance Jennings, who has been in the thick of the Christchurch flu outbreak, said it was a matter of waiting to see whether the virus spread north.
The outbreak in Canterbury had been severe, surpassing that of 2010 and approaching that of 2009, he said.
In terms of patients in intensive care, the burden on Christchurch Hospital from influenza had not been as great this year as it was during the swine flu - H1N1 - pandemic in 2009.
In terms of hospital admissions and pressure on the emergency department it was approaching that of 2009.
The same sort of pattern did not seem to be happening elsewhere, though figures from Waitemata District Health Board were high.
The season was moving on and he would have expected to have seen clusters of infections in other centres. In 2009 the outbreak covered most of the country. This year it was largely in Canterbury.
"What we learn about influenza is to expect the unexpected," Dr Jennings said.
Latest data from ESR show the consultation rate for influenza-like illnesses was 108.5 out of a patient population of 100,000 in the week to July 22. That is the highest rate this winter but well within the rate of 50-249 considered indicative of normal seasonal influenza activity.
Canterbury District Health Board had the highest rate for the week at 238.3, with 169 cases from selected "sentinel" GP clinics. Next was South Canterbury with a rate of 220.4 and 17 cases, then Waitemata with a 216.7 rate and 21 cases, and Southern - Otago and Southland - with a rate of 177.9 and 102 cases.
The flu vaccine available this year still offered significant protection, Dr Huang said.
Vaccination was the most effective tool to prevent flu-like illnesses.
She was cautious about drawing any conclusions from the comparatively high consultation rate in Waitemata, as only a small small number of clinics in the area participated in the sentinel programme.
She did not know why the southern areas had higher rates than the rest of the country, but said weather could be a factor, and the immunity of the population in those areas could also be lower.
Dr Jennings wondered whether the Christchurch earthquakes could have been a factor.
Canterbury had been under severe stress and some houses had more than one family living in them, businesses were sharing premises, and until recently schools had been sharing classrooms, he said.
All those factors could have come together in the cold weather.
But Dr Huang said the earthquakes did not explain the high consultation numbers south of Christchurch.