This year has seen the biggest whooping cough outbreak in decades and researchers now think they know why.
There have been more than 26,000 cases of Pertussis, or whooping cough, across the country this year, the most in more than half a century.
A new report in the New England Journal of Medicine offers one explanation: a safer pertussis vaccine introduced in the 1990s loses its effectiveness faster than expected.
Still, Dr. Jose Hernandez, a family physician at McLeod Seacoast Medical Center in Little River says infants are much better off getting vaccinated than not.
"By and large, 90 percent of most infections are in patients age 6 months or younger and it's most likely because they haven't received a majority of their immunizations, so it is working," Hernandez said.
Infants who are not vaccinated have an 80 to 100 percent chance of getting whooping cough if they come into contact with someone who's infected, Hernandez said.
That risk drops to 20 percent for people who are immunized, so he said even if the vaccine isn't as effective as experts thought, it's still better for kids to get those shots.
"You're still going to get at least a 70 percent benefit, so yes, I would definitely recommend it."
Health experts recommend children get five shots for whooping cough before age 6. Hernandez said if parents are worried about the weakness of the vaccine, they can have their kids get booster shots.
"There is a booster now they recommend between 11 and 12 years of age and then after that every ten years."
Hernandez said Southern states do better at immunizing children than other regions of the country. He said the whooping cough outbreak is much worse in Western states, where fewer children get immunized. That's another sign the vaccine is working, he said.
Hernandez added that about ten percent of whooping cough cases develop into pneumonia and about one percent of people who get pertussis will die from it.
