Whooping cough, or pertussis, is also called the "100 Day Cough." The violent coughing fits can be especially dangerous to babies. There is no course of antibiotics or medication that shortens its duration. So health officials say the best way to treat it is not to get it at all.
Because of whooping cough outbreaks, some local schools experienced some disruption.
"I had a friend whose whole school was shut down for a whole week because too many people had a cough," said 8th-grade student Christian Walton.
Now when Christian returns to school in September, he'll find he'll need to prove he's had a Tdap vaccine booster shot. This new shot combines protection against tetanus, diptheria and whooping cough, and is a requirement for 7th- through 12th-graders. The requirement goes into effect in July.
"Why wait for the line at the doctor's office before the fall? Why not get the vaccination now?" said Dr. Jonathan Fielding, director of the L.A. County Dept. of Public Health.
At Kaiser Permanente L.A. Medical Center, the county department of public health outlined the new mandate. It's part of an overall plan to stop the worst whooping-cough outbreak in California since 1947.
The disease killed four infants in Los Angeles County last year. The goal is to get anybody who is near babies immunized.
"The more children we have who are not protected, the more chances we have of people getting infected and spreading the disease to other people," said pediatric Dr. Rebecca Crane.
Currently, half of children in L.A. County between the ages 13 and 17 have not received the Tdap booster shot. The new law will help "tweens" comply, health officials say there's not much they can do to make adults comply, except to educate them.
"I don't think that most adults fully understand that they in fact are at risk, that they are probably not fully protected, and they can easily transmit it to children," said Fielding.
Thanks to his mom, Christian got his booster shot. But if parents aren't clued in, Christian says tween-aged kids are old enough to take charge of their own health.
"Just check in to make sure that you're all up to date," said Christian.
Boosters are required for any child who hasn't had the shot since age 7.
Fielding says kids ages 11 to 12 should also get a vaccine for meningococcal disease.
Even if you've had a tetanus booster shot recently, you don't have to wait to get the Tdap combination booster shot.