It's getting chilly outside and flu season is knocking on the door. But the Cypress Health Region doesn't recommend being too hospitable to the viruses.

It takes a couple weeks for the human body to build up an immunity after being vaccinated, so the health region has begun administering flu shots.

Dr. David Torr is a consulting medical health officer with Cypress Health Region, and says the whole process of creating a vaccine is quite something.

When flu season strikes differs depending on latitude. For southwest Saskatchewan, it runs from November through to around June, which is the opposite if you were to go 50 degrees south of the equator.

At the equator, Torr says flu season is kind of "on-off" throughout the year.

It takes about six months to create a vaccine, and as viruses are always mutating to become stronger, researchers have their work cut out for them.

Research and surveillance centres are strategically placed around the world, and they monitor viruses circulating based on people admitted to hospital with the flu. Then based off what viruses the researches see, they develop a vaccine for what they predict will be viruses hitting half a year later.

"I always say that as scientists and for us in health, when we sit at our desks and plan strategies against infections, I have a feeling the infections also sit at their own desks and board meetings and strategize on how they're going to counter us," said Torr.

The vaccine is not part of the live virus, but rather proteins extracted from it - so Torr says you can't get an infection from the vaccine.

And if someone already has the flu, Torr says receiving the vaccination is still a good idea, as there are four different variations of viruses in the vaccine - and that person may only have the flu from one of them.

"It's actually useful for you to get the vaccine, because you may have had one of the types that is circulating," he said. "The vaccine has four components that will protect you against, and we do have more than one type that circulates in the season."

The better the vaccination formula matches the viruses circulating, the more effective flu shots are.

But the challenge for scientists is staying ahead of the conniving infections.

"It's survival of the fittest," said Torr. "And they don't want eliminated."