Next fall, seventh-through12th-grade students in California will be required under a new state law to get a whooping cough booster shot before starting school, health officials said this week.
Before Gov. Arnold Schwarzenegger signed Assembly Bill 354 last week, California had been one of only 11 states that did not require middle school students to get a booster shot against whooping cough, or pertussis.
The legislation had been stalled for several years amid concerns that California would have to pay hundreds of thousands of dollars for vaccinations for children on Medi-Cal, the government insurance program for the poor.
The newest number, released Wednesday, makes this year's pertussis epidemic the largest to hit the state since 1950, when 6,613 were infected.
The latest report shows that there are 13.5 pertussis cases per 100,000 people, a ratio that is the highest since 1959, when there was a pertussis rate of 16.1 cases per 100,000.
The latest number of pertussis cases is a significant jump over the previous week's figure of 4,461 cases. But one reason for the big jump was caused by the delivery of delayed pertussis reports from Los Angeles County to state health officials.
Studies show that undiagnosed family members are most likely to infect infants with whooping cough. Most vulnerable to whooping cough are infants too young to be immunized; nine babies, all less than 3 months old, have died so far this year in California.
Just 43.7% of California adolescents had the vaccine for whooping cough, known as Tdap, in 2008, according to the Centers for Disease Control. That rate exceeded the national average of 40.8%, but was lower than some states that require the shot for their middle school students.
Booster shots are important for adolescents and adults because immunity to the bacterial disease can begin to fade as early as five years after receiving an inoculation.
Dr. Helene Calvet, Long Beach's health officer, urged parents to take action to get their teenagers Tdap booster shots if they haven't already done so.
"There is a statewide epidemic, and it's starting to affect our students," Calvet said in a statement.
According to the California Department of Public Health, all students entering seventh through the 12th grades will have to show proof of a Tdap booster shot before starting school in fall 2011. They should receive the Tdap shot on or after their 10th birthday.
For the 2012 school year, only seventh-graders will have to show proof of a Tdap booster shot before the fall semester. Students who are allergic to the vaccine or whose parents express a philosophical objection to inoculations can seek an exemption from the vaccine requirement.