The whooping cough is back. In 2012, there were nearly 50,000 infections in the U.S. -the most since 1955- and a death rate in infants three times that of the rest of the population. Unsure of why there was a resurgence, public health officials pointed to the waning effectiveness of the current vaccine and growing anti-vaccine sentiment as the most likely culprits.

But a new study by Santa Fe Institute Omidyar Fellows, Ben Althouse and Sam Scarpino, points to a different source of the outbreak; vaccinated people who are infected but aren’t displaying the symptoms of whooping cough. Their research suggests that the number of people transmitting the disease, though they have no symptoms, may be many times greater than those transmitting with symptoms. Their findings are published in the journal BMC Medicine.                                                                                                      

From the article:

“In the 1950s, highly successful vaccines based on inactivated pertussis cells (the bacteria that causes whooping cough) drove infection rates in the U.S. below one case per 100,000 people. But adverse side effects of those vaccines led to the development and introduction in the 1990s of acellular pertussis vaccines, which use just a handful of the bacteria’s proteins and bypass most of the side effects (currently given to children as part of the Tdap vaccine).

The problem is, the newer vaccines might not block transmission. A January 2014 study in PNAS by another research team demonstrated that giving baboons acellular pertussis vaccines prevented them from developing symptoms of whooping cough but failed to stop transmission.”

Using those results, the two researchers turned to the CDC for whooping cough case counts, genomic data on the pertussis bacteria, “and a detailed epidemiological model of whooping cough transmission to conclude that acellular vaccines may well have contributed to — even exacerbated — the recent pertussis outbreak by allowing infected individuals without symptoms to unknowingly spread pertussis multiple times in their lifetimes.”

(So then, if you don’t vaccinate your child it’s NOT your fault. Don’t worry, we already knew that.)

Their model also showed that if whooping cough can be spread through the vaccinated population, “herd immunity” would only work with vaccination levels OVER 99 percent. And that’s clearly not going to happen. But that wasn’t only bad news for vaccine supporters; the practice of cocooning, where mothers, fathers, and siblings are vaccinated to protect newborns, isn’t effective. Ben Althouse said, ‘It just doesn’t work, because even if you get the acellular vaccine you can still become infected and can still transmit. So that baby is not protected.”

The pair stress that even though the vaccine doesn’t work, people should continue to get it (we saw that coming) because it prevents the most debilitating effects of whooping cough. Or, you could just boost your immune system but that’s my two cents, everyone needs to do what’s best for their family.