DALLAS -- According to the Texas Department of State Health Services, there have been more than 1,500 cases of pertussis, also called whooping cough, in Texas. That's a 61-percent increase over last year.
There are outbreaks across the country. Because the disease can be deadly, scientists are studying the best ways to curb the infection.
According to new research in the Journal of the American Medical Association, 98 percent of children who get all five doses of the pertussis vaccine before kindergarten are protected. But that protection fades significantly - down to 70 percent - in less than a year.
"The older vaccine seemed to be more effective, but there were more side effects associated with it," explained Children's Medical Center's Dr. Jeffrey Kahn, an infectious disease specialist. "So we substituted safety for efficacy."
Dr. Kahn said pertussis surges every three or years or so.
Last year, the hospital saw just 14 cases. This year, there have been more than 113, with four deaths.
"Their breathing becomes more labored and they're susceptible to other bacterial pneumonias when they have pertussis, and the lungs get very stiff and there's inadequate gas exchange, and ultimately they die of pneumonia," Dr. Kahn said.
In every case, regardless of how long the vaccine lasts, Kahn said an unvaccinated person gave the disease to a child.
Researchers say a booster shot is recommended starting at age 11. Pregnant women and those coming in contact with infants who are not fully vaccinated are also encouraged to get the booster.