Breaking News Emails

Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.
 / Updated 

California’s suffering its worst epidemic yet of whooping cough since the vaccine came out, and it’s likely to get worse, state health officials said Thursday.

The new vaccine’s to blame. Parents got upset at the side-effects of the older vaccine, which could be painful and sometimes caused seizures. But the new formula is both more gentle and its effects wear off. The result? Outbreaks and epidemics of the bacterial infection.

The last epidemic in California, in 2010, made 9,000 people sick and killed 10 babies. So far this year, 9,935 cases have been reported and one baby has died, Kathleen Winters of California’s health department wrote in the CDC’s weekly report on disease.

“Prenatal care providers are encouraged to provide Tdap to pregnant women."

Babies are the most vulnerable, so pregnant women should be vaccinated in the last few weeks of pregnancy so their immune system can also protect the newborn, the Centers for Disease Control and Prevention says.

The vaccine, called Tdap for adults, protects against tetanus, diphtheria and pertussis, the medical name for whooping cough.

“Prenatal care providers are encouraged to provide Tdap to pregnant women or refer patients to obtain vaccine from an alternative provider, such as a pharmacy or local public health department,” Winters wrote.

Most of the babies who got sick were born to mothers who did not get vaccinated during pregnancy, Winters found. Some of the moms got vaccinated after giving birth but this doesn’t protect the baby.

Children get a slightly different vaccine from the one given adults. It’s called diphtheria, tetanus and acellular pertussis, or DTaP, and they are supposed to get it at 2, 4 and 6 months of age. Everyone's supposed to get a booster every 10 years or so.

Newborns too small to be vaccinated are vulnerable.

“During the 2010 pertussis epidemic in California, the main strategy used to protect infants was ‘cocooning’ (i.e., vaccinating contacts of infants so they do not transmit pertussis to the infant),” Winters wrote. “However, this strategy is difficult to implement, and even if all anticipated contacts could be immunized, infants could still be exposed to infected persons in the community.”

Whooping gets its name from the nagging cough it causes that can make children gasp for air, making a distinctive whooping sound. But it’s not so serious in adults and they may not realize that a persistent cough is being caused by pertussis.

"It is likely that the ‘new normal’ will be higher disease incidence throughout pertussis cycles."

As for the epidemics, get used to them, the CDC and California Department of Health said.

“As long as currently available acellular pertussis vaccines are in use, it is likely that the ‘new normal’ will be higher disease incidence throughout pertussis cycles,” the report reads.

“However, it is important to put the current pertussis epi­demic in historical perspective," they added. Before the vaccine, whooping cough made hundreds of thousands of people sick and killed thousands of babies every year. "Therefore, despite the limitations of currently available pertussis vaccines, they continue to have an important impact on pertussis.”

Globally, whooping cough kills nearly 300,000 people a year.