GRAND RAPIDS (WZZM) -- The illness, bringing fever, chills, coughs, and misery to hundreds in West Michigan, is increasing.
The flu continues to spread. The number of confirmed cases more than doubled in just one week in Kent County.
According to the Kent County Health Department, there are now 242 confirmed cases from September 2012 through December 31, 2012. That's up from 112 a week ago.
In 2011, there were just six reported cases during the same three month stretch.
Spokeswoman Lisa LaPlante says there isn't one reason for the increase.
It could be that more people have been together inside now that it's cold out. For example, holiday shoppers pack into stores or families gathering for the holidays.
It could be that some people waited to get flu shots.
But it could also be that more physicians are testing for the flu now, because they're prescribing prescription medications within the first day or two symptoms appear.
The flu shot or flu mist experience is already hard enough on a child.
But parents should be prepared, as their children may still get the flu even after being vaccinated.
"It happens," said LaPlante.
She says it happens to all ages.
This year's flu vaccine is designed to protect against three types of viruses.
But the health department reports 98% of the confirmed flu cases are either Type A or Type B strains and both strains are found in this year's vaccine.
"Some people might have already been exposed to the flu before they got the shot, and it's already taking hold of them," she said.
The shot takes at least two weeks to take effect in your body, maybe longer.
"The vaccine is 75-80% effective, if received on time," she said.
Another reason you may get caught with a fever and a sore throat? There are about 400 different viruses; again, the 2012-2013 vaccine only protects against three.
"Because there are only three you're only getting the shot for, you don't know which one you're going to be exposed to," LaPlante said.
So how does a vaccine work? It works with your body's natural defenses to develop immunity to disease.
According to the CDC, a shot, with a weakened form of the disease virus, is injected into the body.
The body forms antibodies to fight off the invaders.
So if the actual virus ever attacks you, the antibodies return to destroy them.
Now all you have to do is sign you and your children up for a flu shot, and hope it takes effect before the bug hits your workplace or school district.
Also, take some relief in this:
If you get a shot, and still get the flu, LaPlante says you likely won't get it as bad as someone who didn't get a shot.
But if the flu hits, she says to stay home 24 to 48 hours after your symptoms subside.
LaPlante says emergency rooms and doctors' offices do not track who got a vaccine when reporting cases to the health department.