Now that the swine flu vaccine is finally in the country, at-risk groups are being urged to get inoculated. But while the Irish government has invested millions of euro in orders for the vaccine from pharmaceutical companies, it is interesting to note that one country is taking a different approach.

The Canadian government, and more specifically the provinces of Quebec, British Columbia, Alberta, Saskatchewan, Ontario and Nova Scotia, have suspended the 'normal' seasonal flu shots for anyone under 65 in response to a recent study there.

The lead researcher, Danuta Skowronski, of the British Columbia Centre for Disease Control, and Gaston De Serres, of Laval University, have confounded infectious-disease experts by suggesting that people vaccinated against seasonal flu are twice as likely to catch swine flu.

Panel

An international panel is currently scrutinising their data. Dr Ethan Rubinstein, head of adult infectious diseases at the University of Manitoba, who has read the study, said it appeared sound.

"There are a large number of authors, all of them excellent and credible researchers," he said. "The sample size is very large, at 12 or 13 million people."

The vaccine suspensions do not apply for people over 65. Seniors are more susceptible to severe seasonal flu. At the same time, they carry antibodies from a 1957 pandemic that seem to neutralise the current version of swine flu.

In 1981 R Edgar Hope Simpson, who became famous in the late 1960s after he discovered the cause of shingles, proposed that a principal cause of seasonal influenza is linked with the deficiency of solar radiation which triggers the production of vitamin D in the skin.

Vitamin D deficiency is common in the winter as we receive it in large amounts from the sun and in smaller quantities from oily fish like mackerel, herring, sardines and foods like eggs and fortified milk.

Vitamin D is crucial in boosting the immune system and defending itself against invading organisms.

The unrecognised epidemic of vitamin D deficiency is a contributing factor of many chronic debilitating diseases as adequate vitamin D is required to support multiple organs in the body. Vitamin D deficiency affects the immune system's capacity to regulate itself.

The current dietary guideline for humans is to consume 50-200 IU of vitamin D a day. However the American Journal of Clinical Nutrition's Dr Michael Hollick recommends levels as high as 50,000 IU. It is impossible for people in Ireland to obtain these quantities from their diet.

Our summer was on a Thursday this year and I missed it as I was working that day -- but I knew that a single, 20-minute, full-body exposure to summer sun will trigger the delivery of 20,000 units of vitamin D into the circulation of most people within 48 hours.

Synthesis

Twenty-thousand units, that's the single most important fact about vitamin D. Compare that to the 100 units you get from a glass of milk, or the several hundred daily units the Government recommends as 'adequate intake'.

The reality is that the sun does not shine in Ireland too often and our synthesis ceases from October to March.

If the sun does come out the use of sunblock and shades increases and these products reduce vitamin D synthesis by 95pc.

We spend too much time indoors. We have evolved from cavemen in black holes to cavemen in offices and the excess layers of clothing we wear further inhibit our vitamin D absorption.

If we don't eat fish in large enough quantities to obtain vitamin D, and our sun exposure is minimal, we are left to look for alternatives.

Dr John J Cannell began testing his patients -- who came directly from prison and so got little opportunity for sun exposure -- for vitamin D. After finding out that their levels were low, he started to prescribe supplements.

When subsequently tested, results showed a reduction of all types of flus and respiratory infections. This led to further research where he settled on the theory that winter-time vitamin D deficiency predisposes humans to influenza epidemics.

- Damien Maher