Influenza has arrived
29 May 2002
Influenza has arrived
TO DATE more New Zealanders than last year have opted to be vaccinated against influenza, but the Ministry of Health is still urging others to do the same as winter, and the influenza virus, set in.
In the week ending May 24, Taranaki recorded the highest number of doctor's consultations for influenza-like illness; 115.4 patients per 100,000 population, followed by Eastern Bay of Plenty; 92.3 patients per 100,000 population. The number of patients seeing their doctor for influenza is normal for the start of the influenza season.
Fourteen* of the country's 21 District Health Boards have already vaccinated as many people as they did last year. For the week ending 23 May vaccine usage at Counties-Manukau DHB was 11 percent up on last year's total, with Auckland DHB nine percent ahead.
Ministry spokesman Dr Lance Jennings said there was still time to be immunised, even though it takes 10 to 14 days for the vaccine to give full protection.
"Vaccination is the best protection against influenza, especially for those at risk, even if they are fit and active. It is not too late."
Until the end of June the Ministry of Health is funding influenza vaccinations for people aged 65 years and over, as well as adults and children under 65 with certain chronic medical conditions.
Chronic medical conditions can include heart disease, stroke and related diseases, ongoing respiratory diseases like bronchitis or asthma, diabetes, ongoing kidney disease, most cancers and other conditions including rheumatoid arthritis, organ transplants or HIV/AIDS.
"For people with these conditions influenza can trigger serious complications such as pneumonia which in turn can lead to hospitalisation or death."
Dr Jennings said because the influenza virus changes regularly, the vaccine is updated annually. "This is why people need to be vaccinated each year regardless of having the vaccine last year."
"Many of the patients diagnosed with influenza during May had the A/Moscow virus which can be particularly nasty for the elderly. This year's vaccine protects against this strain, as well as the A/New Caledonia and B/Sichuan strains."
"We estimate that over 48,000 New Zealanders had influenza during the 2001 season, with 379 people admitted to hospital with complications brought on by this illness."
Meanwhile, New Zealand's comprehensive influenza surveillance system has discovered a new strain of mild influenza in New Zealand.
Identified as Influenza B/Hong Kong, this virus has been circulating in Asia for 15 years and became more widespread in the Northern Hemisphere during their winter.
It arrived in Australia this year, and in May it was discovered in one patient in the Waikato.
Dr Jennings said while this virus is not covered by this year's vaccine, its discovery should not cause undue alarm as influenza B viruses generally cause a milder illness in elderly and high risk adults.
A decision will be made in October this year whether to include the B/Hong Kong in next year's vaccine. It has already been included in the Northern Hemisphere's vaccine for their winter.
This year's improvements in vaccine uptake have led GlaxoSmithKline to source additional vaccine to cover anticipated usage over the next month.
For more information contact: Hayley Brock Media Advisor Ministry of Health (04) 496 2115, 025 495 989 http://www.moh.govt.nz.html
Influenza Surveillance Update
17 May to 24 May 2002
In the past week, a total of 95 consultations for influenza-like illness were reported from 90 general practices in 21 out of 24 health districts. This gives a weekly consultation rate of 27.4 per 100,000 patient population.
The figure below compares the consultation rates for influenza-like illness for each health district over the past week. Taranaki had the highest consultation rate; 115.4 per 100,000, followed by Eastern Bay of Plenty, 92.3 per 100,000.
(Embedded image moved to file: pic20485.pcx)
NB [ ] indicates health districts that are not participating * indicates no cases for the week from the health district
10 May to 17 May 2002 In the past week, a total of 84 consultations for influenza-like illness were reported from 90 general practices in 21 out of 24 health districts. This gives a weekly consultation rate of 24.3 per 100,000 patient population.
The figure below compares the consultation rates for influenza-like illness for each health district over the past week. Eastern Bay of Plenty had the highest consultation rate (184.6 per 100,000), followed by Taranaki (128.2 per 100,000).
(Embedded image moved to file: pic03093.pcx) NB [ ] indicates health districts that are not participating * indicates no report for the week from the health district
Health Districts: NL Northland, NW North West Auckland, CA Central Auckland, SA South Auckland, WK Waikato, BE Eastern Bay of Plenty, RO Rotorua, TG Tauranga, GS Gisborne, RU Ruapehu, TP Taupo, HB Hawkes Bay, TK Taranaki, MW Manawatu, WG Wanganui, WN Wellington, WR Wairarapa, HU Hutt, NM Nelson-Marlborough, CB Canterbury, SC South Canterbury, WC West Coast, OT Otago, SO Southland.
A weekly rate below 50 consultations per 100 000 patient population is described as baseline activity. A weekly consultation rate of 50-249 is considered indicative of normal seasonal influenza activity. Within the normal seasonal activity, 50 to 99 is low activity, 100-149 moderate, and 150 to 249 high. A rate of 250-399 indicates higher than expected influenza activity and 400 consultations per 100,000 patient population indicates an epidemic level of disease.
District Health Board influenza vaccine uptake Twelve of the 21 district health boards have already exceeded their previous level of uptake of the influenza vaccine. They are: Auckland (9 percent more vaccine used to date), Bay of Plenty (1 percent more vaccine used to date), Canterbury (2 percent), Counties-Manukau (11 percent), Hawke's Bay (5 percent), MidCentral (3 percent), Tairawhiti (3 percent), Taranaki (6 percent), West Coast (7 percent), and Whanganui (2 percent).
Hutt, Lakes, Nelson-Marlborough and Waikato District Health Boards have achieved their previous level of uptake of the influenza vaccine.
Northland and South Canterbury are just one percent behind their previous level of uptake, Capital and Coast and Waitemata are three precent behind, Southland and Wairarapa are four percent behind, and Otago is five percent behind.
How are the statistics collected? There are two parts to the influenza surveillance system in New Zealand - general practice (GP) surveillance and laboratory-based (mainly hospital) surveillance.
General practice surveillance (May to September)
In 2002, national influenza GP surveillance will be done from May to September. Local surveillance co-ordinators recruit general practices within their region to participate on a voluntary basis. GPs record the number of consultations for influenza-like illness each week and the age group of each of these suspected cases.
Each practice is also asked to collect throat or nose swabs from patients seen with an influenza like illness each week. The swabs are sent to a regional virus diagnostic laboratory and/or ESR for strain identification.
Laboratory-based surveillance (year round)
In addition to positive identification of the influenza virus from GP surveillance, year-round surveillance of influenza (and other viruses) is carried out by the four regional virus diagnostic laboratories at Auckland, Waikato, Christchurch and Dunedin Hospitals, and by ESR's virology laboratory. Both the ESR and Auckland Hospital laboratories are designated WHO National Influenza Centres.
Each week, the regional virus diagnostic laboratories report all viral identifications including influenza, largely from hospital in-patients and outpatients, to ESR, where the data is collated and reported nationally.