In California, where memories of last year's whooping cough outbreak are still fresh, students have just days to comply with a mandatory vaccination law. But not everyone is falling willingly into line, as CBS News correspondent John Blackstone reports.
At Southgate High School in Los Angeles, it's been a painful start to the new year.
Under pressure to comply with a new statewide mandate, nurses are doling out shots as fast as they can.
"All the high schools and the 7th graders and 8th graders need to have a TDAP shot," said Elna Jane Salazar, a school nurse at Southgate.
The TDAP shot protects against whooping cough, a highly contagious and preventable disease that was once nearly eradicated. But last year it made a huge comeback in California and ten infants died.
Over the summer, ads urged parents to vaccinate their children before the start of school. But thousands of students still haven't complied. In Sacramento, kids are now getting yanked from class.
"They were kicking me out of school because I didn't have my shot," says Saveya Barrow, a student.
In Berkeley alone, some 600 students have an urgent assignment: show proof they've been vaccinated or roll up their sleeves and get the shot. The deadline is this Thursday and excuses won't be tolerated.
Blackstone asked WillIiam Huyett, superintendent of Berkeley Unified School District: "There's potentially a lot of kids next week who will be told you can't go to school?
"That's right," he responded, "and California with a dropout rate as high as it is, we can't afford to lose any students so I do worry about that with laws like this."
Since 2007, 40 states have passed laws requiring secondary school students to be up to date on the whooping cough vaccine.
"Whenever you mandate anything there's going to be some discussion quite appropriately and some pushback," said Dr. William Schaffner of Vanderbilt Medical School's Department of Preventive Medicine.
In California, parents can opt out of the whooping cough mandate if they're personally opposed to vaccines. But only a small percentage is expected to do so -- much to the relief of state health officials.