Protection Against Whooping Cough Waned During the Five Years After Fifth Dose of DTaP

[xchrom]

http://www.sciencedaily.com/releases/2012/09/120912184514.htm

ScienceDaily (Sep. 12, 2012) — Protection against whooping cough (also called pertussis) waned during the five years after the fifth dose of the combined diphtheria, tetanus, acellular pertussis (DTaP) vaccine, according to researchers from the Kaiser Permanente Vaccine Study Center. The fifth dose of DTaP is routinely given to 4- to 6-year-old children prior to starting kindergarten.


The study appears in the current online issue of the New England Journal of Medicine.
This is the first study to specifically focus on the large population of highly vaccinated children who had exclusively received DTaP vaccines since birth and for whom enough time had passed since their fifth dose that DTaP vaccine waning could be measured, said the researchers. They explained that the study period included a large pertussis outbreak that occurred in California during 2010. Researchers examined the relationship between time since vaccination with the likelihood of a positive pertussis test in the Kaiser Permanente Northern California population, which includes 3.3 million members in an integrated care system with electronic medical records and a central laboratory.

Researchers compared 277 children, 4 to 12 years of age, who were positive for pertussis with 3,318 children who were negative for pertussis and separately with 6,086 matched controls. They assessed the risk of pertussis in children from 2006 to 2011 in California relative to the time since the fifth dose of DTaP and found that protection from pertussis after the fifth dose of DTaP vaccine wanes more than 40 percent each year. The amount of protection remaining after five years depends heavily on the initial effectiveness of the fifth dose of DTaP, according to Nicola Klein, MD, PhD, co-director of the Kaiser Permanente Vaccine Study Center and the lead author of the study.

If the initial effectiveness of the fifth dose of DTaP was 95 percent, the effectiveness of DTaP would decrease to 71 percent after five years. Whereas if the initial effectiveness was 90 percent, it would decline to 42 percent after five years, explained the researchers.

[SheilaT]

1. I'm somewhat under the impression that the

pertussis vaccine doesn't confer permanent immunity, and that it may not be such a bad idea for adults to get a booster now and then. I know the tetanus portion wears off.

I'm also under the impression that if someone actually gets whooping cough, a permanent immunity results.

[PADemD]

2. My doctor told me that you can get whooping cough more than once.

So I got a booster shot.

[SheilaT]

3. Interesting.

I recently (a couple of years ago) had the booster. I actually am more concerned about tetanus than the other two.

It's conventional wisdom that chicken pox can only be gotten once, but I've had enough reports from moms, especially in the years when my two were in the chicken-pox-likely age, of kids who'd gotten it more than once that I hypothesize that chicken pox has from three to five sub-groups, and depending on which one you get, how likely you are to get it again. Or maybe some strains consist of more than one sub group. Now, I'm not a virologist, and I've never discussed my hypothesis with experts in the field, but there's an underlying logic that I like. And notice I'm calling it a hypothesis, because my idea is no where near the level of a theory.