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Sun Mar 9, 2014, 03:46 PM

FDA study helps provide an understanding of rising rates of whooping cough ~ FDA

“There were 48,000 cases reported last year despite high rates of vaccination,” said Anthony S. Fauci, M.D., director of the NIH’s National Institute of Allergy and Infectious Diseases. “This resurgence suggests a need for research into the causes behind the increase in infections and improved ways to prevent the disease from spreading.”

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While the reasons for the increase in cases of whooping cough are not fully understood, multiple factors are likely involved, including diminished immunity from childhood pertussis vaccines, improved diagnostic testing, and increased reporting. With its own funds plus support from the National Institutes of Health (NIH), the FDA conducted the study to explore the possibility that acellular pertussis vaccines, while protecting against disease, might not prevent infection.

“There were 48,000 cases reported last year despite high rates of vaccination,” said Anthony S. Fauci, M.D., director of the NIH’s National Institute of Allergy and Infectious Diseases. “This resurgence suggests a need for research into the causes behind the increase in infections and improved ways to prevent the disease from spreading.”

The FDA conducted the study in baboons, an animal model that closely reproduces the way whooping cough affects people. The scientists vaccinated two groups of baboons – one group with a whole-cell pertussis vaccine and the other group with an acellular pertussis vaccine currently used in the U. S. The animals were vaccinated at ages two, four, and six months, simulating the infant immunization schedule. The results of the FDA study found that both types of vaccines generated robust antibody responses in the animals, and none of the vaccinated animals developed outward signs of pertussis disease after being exposed to B. pertussis. However, there were differences in other aspects of the immune response. Animals that received an acellular pertussis vaccine had the bacteria in their airways for up to six weeks and were able to spread the infection to unvaccinated animals. In contrast, animals that received whole-cell vaccine cleared the bacteria within three weeks.

This research suggests that although individuals immunized with an acellular pertussis vaccine may be protected from disease, they may still become infected with the bacteria without always getting sick and are able to spread infection to others, including young infants who are susceptible to pertussis disease.


More at FDA.Gov

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Reply FDA study helps provide an understanding of rising rates of whooping cough ~ FDA (Original post)
mzmolly Mar 2014 OP
mzmolly Mar 2014 #1
Warpy Mar 2014 #2
mzmolly Mar 2014 #3
Tumbulu Mar 2014 #4
mzmolly Mar 2014 #5

Response to mzmolly (Original post)

Sun Mar 9, 2014, 03:47 PM

1. Study results here:

http://www.pnas.org/content/111/2/787.short

Abstract

Pertussis is a highly contagious respiratory illness caused by the bacterial pathogen Bordetella pertussis. Pertussis rates in the United States have been rising and reached a 50-y high of 42,000 cases in 2012. Although pertussis resurgence is not completely understood, we hypothesize that current acellular pertussis (aP) vaccines fail to prevent colonization and transmission. To test our hypothesis, infant baboons were vaccinated at 2, 4, and 6 mo of age with aP or whole-cell pertussis (wP) vaccines and challenged with B. pertussis at 7 mo. Infection was followed by quantifying colonization in nasopharyngeal washes and monitoring leukocytosis and symptoms. Baboons vaccinated with aP were protected from severe pertussis-associated symptoms but not from colonization, did not clear the infection faster than naïve animals, and readily transmitted B. pertussis to unvaccinated contacts. Vaccination with wP induced a more rapid clearance compared with naïve and aP-vaccinated animals. By comparison, previously infected animals were not colonized upon secondary infection. Although all vaccinated and previously infected animals had robust serum antibody responses, we found key differences in T-cell immunity. Previously infected animals and wP-vaccinated animals possess strong B. pertussis-specific T helper 17 (Th17) memory and Th1 memory, whereas aP vaccination induced a Th1/Th2 response instead. The observation that aP, which induces an immune response mismatched to that induced by natural infection, fails to prevent colonization or transmission provides a plausible explanation for the resurgence of pertussis and suggests that optimal control of pertussis will require the development of improved vaccines.

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Response to mzmolly (Original post)

Sun Mar 9, 2014, 07:38 PM

2. Interesting.

Few adults get it bad enough to notice it's anything different from a garden variety upper respiratory infection. I wasn't one of the few and it was six months of coughing myself breathless and then getting laryngospasm that someone took it seriously enough to help me get over it.

Children take up to two years to recover from it if they're toddlers and older. Infants often die from it.

I'm now pretty much protected for life. However, if you're likely to be around infants any time in the future, please get vaccinated. Their lives might depend on it.

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Response to Warpy (Reply #2)

Sun Mar 9, 2014, 11:22 PM

3. I think one should wait to expose

an infant to anyone who has been vaccinated recently, given this new information.

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Response to mzmolly (Original post)

Mon Mar 10, 2014, 12:03 AM

4. Isn't this rather obvious?

They switched to the acellular to avoid the 1/100 severe reactions to the whole cell vaccine that forced many to stop the series altogether. The acellular vaccine protects one against the devastating effect of the toxin that the bacteria produces, but not from getting infected. I think it was a good decision as a greater number of people can be protected from the toxin. So the devastating effects of the infection is reduced or eliminated.

But there is more of it around and it seems to me that parents need to keep their infants away from public places until the infants have begun their vaccinations.

Going back to the whole cell vaccine is a really bad idea, IMO.

The great thing is that this acellular vaccine is preventing people from the serious injury that the bacterial infection would normally cause. I think we just need to immunize adults a bit more often, and keep babies out of public places.

And stop blaming the tiny population that does not vaccinate for every imagined problem.

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Response to Tumbulu (Reply #4)

Tue Mar 11, 2014, 11:49 AM

5. I agree.

But there is more of it around and it seems to me that parents need to keep their infants away from public places until the infants have begun their vaccinations.

Going back to the whole cell vaccine is a really bad idea, IMO.

The great thing is that this acellular vaccine is preventing people from the serious injury that the bacterial infection would normally cause. I think we just need to immunize adults a bit more often, and keep babies out of public places.

And stop blaming the tiny population that does not vaccinate for every imagined problem.


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