Despite recent vaccination mandates across California schools, in 2012, cases of whooping cough in the U.S. reached their highest levels in more than 60 years, health officials say.
According to a report out Friday from The Associated Press, “about 42,000 cases were reported last year, the most since 1955. But the Centers for Disease Control and Prevention is still gathering information, and the number could rise to as much as 50,000.”
In California, the most recent numbers from the state’s department of public health show that from Jan. 1, 2012 through April 24, 2012, 169 cases of whooping cough, otherwise known as pertussis, had been reported statewide.
Although the risk of dying from whooping cough is low – nationally, 18 reportedly perished last year from the disease – some health officials are concerned about the vaccine's effectiveness.
A November 2012 report in the Journal of the American Medical Association found that California kids who had been fully vaccinated were less likely to catch whooping cough, but the report also noted that the more time that had passed since children completed the initial recommended immunization regimen -- three doses of the DTaP vaccine (against diptheria, tetanus, and pertussis) at 2, 4 and 6 months, followed by booster shots at 15-18 months and 4-6 years -- the more likely they were to get whooping cough.
The JAMA report finds that the efficacy of the pertussis regimen fell from 98.1 percent within a year of finishing it to 71.2 percent five or more years later, according to estimates by the researchers from the CDC and the California Department of Public Health.
Despite the efficacy decline, an editorial in the JAMA issue still advises a “suboptimal” whooping cough vaccine is still warranted.
The report is in sync with a Kaiser Permanente study published in the New England Journal of Medicine in September.
In California, Assembly Bill 354 was signed into law in September 2010. As a result, California students entering or advancing to grades seven through 12 during the 2011–12 school year were required to be immunized with a pertussis vaccine booster. In July 2012, AB 354 required only students who were entering or advancing into grade seven to 12 show proof of a pertussis booster vaccine (on or after the seventh birthday).
The bill included two exemptions, one for medical reasons and the other for personal beliefs.
The California Department of Public Health recommends the booster for all people 10 years of age and older.
During a July 2012 telebriefing hosted by the Centers for Disease Control and Prevention, health officials discussed a pertussis epidemic in Washington State, which has seen its highest rates of whooping cough in infants younger than one year of age.
“About half of these cases are babies under three months of age. That's because those very young babies are too young to be protected by vaccines that they start getting at two months of age. Their protection instead depends on the immunity of the people around them, especially pregnant women, their mothers. That is why we strongly urge pregnant women and all who will be around babies to be vaccinated. Infants often get pertussis from a family member or household member,” Dr. Anne Schuchat, director for the National Center for Immunization and Respiratory Diseases at the CDC, said during the telebriefing.
She went on to address adolescents.
“We’re also seeing high rates in older children as well. … We realize that by age 10, immunity can wane from the early-childhood vaccines that kids get. That is why we ended up recommending a booster of pertussis-containing vaccine at 11-to-12 years of age.
“Pertussis vaccine remains the single most effective approach to prevent infection,” Dr. Schuchat continued. “It is critical to protect infants and others at high risk. I want to stress that unvaccinated children are at eight times higher risk of getting pertussis compared to children fully vaccinated.”
The good news? Some experts say whooping cough tends to run in multi-year cycles, and many believe 2012 appears to have been a peak.