Influenza, as we know, is a virus which, because of its infectiousness, can easily become an epidemic or even a pandemic in a short period of time. Though my own bouts of the flu have always been no more than a minor inconvenience, for the elderly, those with weakened immune systems, and perhaps also children, the flu can be fatal. During the Spanish flu of 1918, for example, millions of people died.
The process of making flu vaccine takes about six months. First, samples of that year's flu strains are obtained; these will be inoculated into chicken eggs. (The flu virus mutates at an extremely rapid rate, so new samples of the virus must be used each year. That's also why you're supposed to get a shot every year: this year's vaccine isn't the same as the one you got last year.) Canada's virus samples are obtained annually from the US Centre for Disease Control and Prevention and from the World Health Organization. The chickens that lay the eggs must be raised on farms that follow stringent guidelines for cleanliness, because chickens typically harbour bacteria like salmonella. The eggs are innoculated and incubated for several weeks, after which the contents are harvested, as they say, purified, and packaged.
Those with a history of Guillain-Barré syndrome or those allergic to eggs should not get flu shots. I'm not sure why the former is true, but the latter seems pretty obvious.
Public health officials in Ontario, Canada have decided that universal vaccinations are one way to combat the flu in this province, and so for the second year in a row this province is the only jurisdiction in the world to offer free flu shots to all its citizens over six months of age. Last year vaccinations were offered in malls, offices, hospitals, clinics, and doctor's offices; this year the campaign is focusing on the workplace, both because people surveyed last year said this would be the most convenient, and because one of the big arguments in favour of vaccination - at least in the government's eyes - is the high cost of lost productivity: $500 million annually, they estimate. Ontarians can still get a shot at their doctor's office or clinic, however.
The data are not yet analyzed that will tell how many people actually got vaccinated last year (I didn't). And the benefit of universal inoculation is much harder to assess. Though the incidence of flu outbreaks in nursing homes may have decreased by as much as 97%, the greatest overall boon may not be realized until the next flu pandemic, which epidemiologists expect to occur soon.