Could someone explain these quotes from the DTaP insert?

[Kamie]

DS is asleep so I have some time to re-type the info from the DTaP package insert from the Sanofi Pasteaur vax that I don't understand. Here are the quotes and I wrote a question after the quote. Thanks in advance to anyone who can help me with this. My son's well visit is Thursday and I like to be well armed with info if needed.

"The protective efficacy of DAPTACEL vaccine against pertussis after 3 doses using the WHO case definition (greater than or equal to 21 consecutive days of paroxysmal cough with culture or serologic confirmation or epidemiologic link to a confirmed case was 84.9% (95% confidence interval [c1] 80.1 to 88.6). The protective efficacy of DAPTACEL vaccine against mild pertussis was 77.9% (95% c1 72.6 to 82.2). Protection against pertussis by DAPTACEL vaccine was sustained for the 2 year follow up period."

Does this mean that after 3 doses of DTaP when people where exposed to pertussis 84.9% where protected from pertussis and 77.9% where protected against mild pertussis?

"For both lots of DAPTACEL vaccine, the geometric mean concentration and percent response to PRN in US infants were significantly lower after 3 doses of vaccine than in Swedish infants. In separate US and Canadian studies in which children received DAPTACEL vaccine at 2,4, and 6 months of age with a fourth dose at 17-20 months (Candadian study) or 15-16 months (random subset from US study) of age, antibody responses to each pertussis antigen following the fourth dose were at least as high as those seen in Swedish infants after 3 doses. While a seriologic correlate of protection for pertussis has not been established, the antibody response to all antigens in North American infants after 4 doses of DAPTACEL vaccine at 2,4,6 and 15-20 months of age was comparable to that achieved in Swedish infants in whom efficacy was demonstrated after 3 doses of DAPTACEL at 2,4, 5 months of age."

Does this mean Swedish infants only need 3 doses for it to be effective and North American infants need 4? Is pertussis stronger in the US? This seems funny to mean.

[NatureMama3]

#1. for the number of participants studied, that appears to be what it means (with 95% confidence rate).

#2. it could mean that or it could mean the swedish shot was formulated differently? or that the 5 instead of 6 months made a difference?

[Spy]

Originally Posted by Kamie

"The protective efficacy of DAPTACEL vaccine against pertussis after 3 doses using the WHO case definition (greater than or equal to 21 consecutive days of paroxysmal cough with culture or serologic confirmation or epidemiologic link to a confirmed case was 84.9% (95% confidence interval [c1] 80.1 to 88.6). The protective efficacy of DAPTACEL vaccine against mild pertussis was 77.9% (95% c1 72.6 to 82.2). Protection against pertussis by DAPTACEL vaccine was sustained for the 2 year follow up period."

Does this mean that after 3 doses of DTaP when people where exposed to pertussis 84.9% where protected from pertussis and 77.9% where protected against mild pertussis?

I wouldn't say so. It's not that easy to establish exposure with any certainty. It looks like in their vaccinated group (about 2.5 thousand children) there were 84.9% less [WHO-defined] cases of pertussis than in the control group and 77.9% less mild cases than in the control group that received DT vaccine (just over 2000 children) during the 2-year follow up period.

[NatureMama3]

agreed! they really don't give anywhere near enough info there to make a conclusion about efficacy. how many children? 10? 100? how do they know they were exposed? were there any "thrown out" due to mitigating circumstances? etc etc etc..

their claims appear to be saying that, but I personally wouldn't use that as my only basis. numbers can be twisted/

[mamakay]

I've traced those Swedish studies back to the original research, and it's still a mess. It was a totally different vaccine (they say the American vax is "similar")...and it was a clinical trial conducted by the menufacturer.

The CDC sums it up like this:
"We don't know how well the pertussis vaccine works. All we know is that 4 doses are better than 3, and 5 doses are better than 4. And it tops out around 85% effective."

Some studies say the vaccine is only 33% effective (against pertussis in general), and others say it's around 66% effective against severe disease.

[LongIsland]

How old is this WHO case definition in the product information sheet? The WHO case definition of pertussis is pretty much the same as ours:

Clinical Case Definition
a cough illness lasting at least 2 weeks with one of the following: paroxysms of coughing, inspiratory "whoop," or posttussive vomiting, and without other apparent cause (as reported by a health-care professional)

Laboratory Criteria for Diagnosis
isolation of Bordetella pertussis from a clinical specimen, or positive polymerase chain reaction (PCR) assay for B. pertussis Case Classification

Confirmed
an acute cough illness of any duration associated with B. pertussis isolation, or

a case that meets the clinical case definition and is confirmed by PCR, or

a case that meets the clinical definition and is epidemiologically linked directly to a case confirmed by either culture or PCR

Probable
a case that meets the clinical case definition, is not laboratory confirmed by culture or PCR, and is not epidemiologically linked directly to a laboratory-confirmed case

http://www.cdc.gov/mmwr/preview/mmwrhtml/rr55e223a3.htm

http://www.who.int/immunization_moni...rveillance/en/

[Kamie]

[QUOTE=LongIsland;7882198]How old is this WHO case definition in the product information sheet?

The product info sheet says november 2006.

So it sounds like the really can't conclude efficacy. I am curious to learn more about what the CDC says about how they don't know how well the pertussis vax works but they say 4 and 5 shots is better. How do they come to this conclusion if they don't know how the vax works?? Can you send me a link to that info?