This disease (and its vaccine) have gotten a lot of press lately and it’s an important conversation to have. The fact is it’s tough to vaccinate for this one. Contrary to common belief, even having the disease doesn’t confer lifelong immunity and the vaccine certainly does not. The older whole cell formulation of the vaccine did a better job, but also had more potential for side effects. We got rid of it, however, because of myths spread in the lay media by the antivaccine movement. More on that below, but first – the disease. Bordetella Pertussis is a bacteria that is spread through respiratory droplets (i.e. it’s airborne) and is highly contagious. It has a very long incubation period (the time between becoming infected and becoming symptomatic) that can range from 7 to 21 days. The initial symptoms are fairly mild and mimic a common cold. The disease then progresses to fits (called paroxysms) of violent coughing in older children and adults. Infants may not all have these coughing spells, sometimes they just become short of breath. Patients will cough to the point that they feel completely out of air and gasp for air, they may vomit or even break their own ribs. The cough is sometimes referred to as the hundred day cough because it can last over 3 months. While this is a bacterial illness, antibiotics really only decrease a patient’s contagiousness, they do not decrease the length of illness by very much. Infants with whooping cough can experience apnea (cessation of breathing) and have a higher incidence of secondary pneumonia. 75% of infants under 6 months with pertussis will be sick enough to be hospitalized.
Now, the vaccine. The first pertussis vaccine was developed by a scientist named Pearl Kendrick (that’s right girls, SHE’S A GIRL! Cool, huh?) in the 1930’s. Her vaccine was immediately put into use and by the 1960’s there were fewer than 10 cases of pertussis per 100,000 people in the US. That’s virtual eradication. Then, in the early 1980’s a TV special called Vaccine Roulette was aired on prime time. It raised fears about the vaccine, which later turned out to be unfounded, but it set in motion a chain of events that led manufacturers to stop making the vaccine altogether. This same chain of events did have some good outcomes. They were the impetus for creating the Vaccine Adverse Event Reporting Service and the Vaccine Injury Compensation Program, which I’ll touch on later because they deserve their own post. Please do read more about the details of this story. Also be aware that Barbara Fisher, whom you’ll read about here, is one of the cofounders of the National Vaccine Information Center. I point this out so that as you’re googling out there you know who’s writing the “information”.
These days, we use the acellular pertussis vaccine, which does have fewer side effects than the whole cell vaccine (it did have some significant side effects, just not epilepsy as its critics claimed). However, it doesn’t work as well. It’s very effective at protecting those who receive it, but it doesn’t always render them non-contagious. Some individuals who have been vaccinated may contract the disease but never develop symptoms, thus spreading it unknowingly. This is obviously problematic. This is not, however, a reason not to vaccinate. If you get your Tdap booster in the third trimester, your newly manufactured immunglobulins will cross the placenta and stay with your newborn for the first 6 months of life (and they’ll be getting their own vaccines at 2, 4, and 6 months). Vaccinating infants is still very effective at protecting those infants. Meanwhile, scientists are still hard at work trying to better understand the problems with the vaccine and make a better product. That’s how science works, after all. Oh, and no, this one doesn’t shed. I’ll do a post on shedding later.