Demand for the influenza vaccine has been so high that some medical practices have been left without supplies.

However, the Ministry of Health is hopeful that a shipment of 95,000 doses received on Thursday will see the country's doctors into next week despite delays in freight and handling because of Easter.

The Ministry of Health's manager of immunisation, David Wansbrough, said 530,000 doses of the vaccine were distributed during March.

He said that was 10 per cent more than last year and enough to vaccinate 13 per cent of the population.

On Thursday, just 85,000 doses were available which, with demand at between 20,000 and 30,000 doses each day, had increased the pressure on medical practices. "It's going quite fast," Mr Wansbrough said.

"Demand is much higher than we expected. We're distributing them as fast as our supply is coming in. We're watching this pretty closely because we don't have a lot in our warehouse.

"We have had some delays in deliveries to some practices so there is some level of frustration around the place. We acknowledge that and we're trying to avoid it as much as possible."

While the current supplies were only enough to "get us through another week or two, the ministry was confident supplies would be kept up.

"We have been getting shipments every week from the companies and as long as they keep those shipments up we should be okay. The schedule's not regular - they're coming whenever they can."

The vaccine also contained a vaccine for swine flu, which Mr Wansbrough is hoping will result in fewer deaths.

Mr Wansbrough said this year's vaccine had been hard to make because the strains were slow to grow and some of the healthcare companies making it had been tied up making vaccines for swine flu.

He said delays were also occurring because of the strict temperature controls around the vaccine's storage and transportation requirements, which meant it could not be distributed any faster.

The Ministry of Health was told by the country's main flu vaccine supplier, Sanofi-aventis, before Christmas that there would be a delay in supplies so staff ordered 450,000 more doses from companies CSL and Solvay.

Mr Wansbrough admitted the increased demand and short supply meant the ministry was paying more for each dose, but he would not divulge the extra cost to taxpayers, citing commercial sensitivities.

He said final figures would not be known until the taxpayer-subsidised doses and the customer-pays figures were counted up at the end of the season.

Meanwhile, influenza levels are "low and at the usual level" for this time of year.

The number of people visiting their doctor with influenza-like illness remains under the "baseline" level of less than 50 consultations per 100,000 patient population.

FLU VACCINE

* Takes months to develop and has a short shelf life.
* Must be stored and transported at temperatures between 2C and 8C.
* Must pass through Customs and quarantine checks, which include whether there were temperature breaches while supplies were being shipped here.