Very Basic Question - Page 2

[mamakay]

Originally Posted by anewmama

so, let me see if I am making any sense of this. So while those vaccines may not provide resistence to transmission, they might reduce the incidences of a disease in the individual and therefore reduce the chances of another individual being infected by someone with one of these diseases. If this is the case, isn't there still a benefit to herd immunity as defined by the more who have the vaccine, then maybe the less chances of a disease and the less chances one would get it?

Have you ever heard of Typhoid Mary? Some of the vaccines basically just make people into temporary typhoid mary's. If you're vaxed for pertussis, and you catch pertussis, and IF the vaccine "works", that means you're carrying pretussis around for a while, spreading it to who knows how many people for who knows how long, never showing "pertussis symptoms" yourself. (more than likely). Same thing with diphtheria.

With a vax like measles, it really, totally works (if it works, which it usually does). Come into contact with the measles virus, and your body just kills it right off before it can replicate enough for you to become contagious. Same with OPV and rubella, and mumps when that vax works.
Prevnar and Hib give a "total" immunity like that, too. (serotype replacement issues aside).

[alegna]

Originally Posted by mamakay

Have you ever heard of Typhoid Mary? Some of the vaccines basically just make people into temporary typhoid mary's. If you're vaxed for pertussis, and you catch pertussis, and IF the vaccine "works", that means you're carrying pretussis around for a while, spreading it to who knows how many people for who knows how long, never showing "pertussis symptoms" yourself. (more than likely). Same thing with diphtheria.

With a vax like measles, it really, totally works (if it works, which it usually does). Come into contact with the measles virus, and your body just kills it right off before it can replicate enough for you to become contagious. Same with OPV and rubella, and mumps when that vax works.
Prevnar and Hib give a "total" immunity like that, too. (serotype replacement issues aside).

-Angela

[amnesiac]

I don't think that this is something that's probably been explored adequately so I'm just theorizing here, but knowing that B pertussis is spread through airborne droplets disbursed via coughing & sneezing - if being vaccinated decreases symptoms of infection then one would be less likely to spread that infection even if you are infected. I mean, if you aren't coughing & sneezing then you can't really be spraying those droplets so much. That's a little bit different situation than Typhoid Mary who was probably innoculating a good amount of the food she cooked since her ability to infect wasn't really related to her symptoms at all.

[mamakay]

How do you know the vaccinated yet infected don't go through the "cold" phase, though? All we really know is that the vaccinated don't tend to get "the cough" as bad for as long, most to some of the time. Everything beyond that is unknown. The possible reduction in transmission could be anywhere along the spectrum of possibilities.

And with diphtheria, with natural and vax immunity...a completely silent carrier state is known.

Neither of those a food handling issues, though, so yeah...that's totally different.

[anewmama]

Originally Posted by mamakay

Have you ever heard of Typhoid Mary? Some of the vaccines basically just make people into temporary typhoid mary's. If you're vaxed for pertussis, and you catch pertussis, and IF the vaccine "works", that means you're carrying pretussis around for a while, spreading it to who knows how many people for who knows how long, never showing "pertussis symptoms" yourself. (more than likely). Same thing with diphtheria.

Yes, have heard of Typhoid Mary but until now, never had to REALLY think about it...: where is the my head is hurting icon?!

So, the vaccination reduces infection in the individual but does not eliminate it's presence, and therefore, does not suppress it's potential transmission to other folks.

Did I get it?

Why is there a difference between IPV and OPV? I know one is killed and one isn't, by why does the body respond differently or affect transmission differently beyond shedding live virus (or is that viri or something?! : )

[amnesiac]

Originally Posted by mamakay

How do you know the vaccinated yet infected don't go through the "cold" phase, though?

I don't have any idea how many do/don't. Never bothered to dig that deeply. And I'm not sure it's something that's even been looked into much. Maybe that's why Adacel uses the disclaimer they do on their promo info at the moment. But, if they don't get the cough that can last 3 weeks or so then they're definitely not spraying the bacteria for as long.

[mamakay]

Yes, have heard of Typhoid Mary but until now, never had to REALLY think about it... where is the my head is hurting icon?!

So, the vaccination reduces infection in the individual but does not eliminate it's presence, and therefore, does not suppress it's potential transmission to other folks.

Did I get it?

Basically.

Why is there a difference between IPV and OPV? I know one is killed and one isn't, by why does the body respond differently or affect transmission differently beyond shedding live virus (or is that viri or something?

It's a matter of "serum immunity" vs. "mucosal immunity". Whatever immunity you get from IPV is more or less limited to your bloodstream. Which means if the virus crosses over, out of your gut, and tries to infect your CNS, you have "immunity" there (assuming the vax works) and won't get paralysis. OPV immunity is actually immunity in your gut...which is where the polio viruses like to hang out and replicate. Polio is mostly a stomach bug that every once in a while goes nuts and infects people's brains, causing paralysis. But most of the time, it's more like rotavirus.

[mamakay]

Originally Posted by amnesiac

I don't have any idea how many do/don't. Never bothered to dig that deeply. And I'm not sure it's something that's even been looked into much. Maybe that's why Adacel uses the disclaimer they do on their promo info at the moment. But, if they don't get the cough that can last 3 weeks or so then they're definitely not spraying the bacteria for as long.

Getting into the length of the cough, even...have you read this?

http://pediatrics.aappublications.or...2/4/909?ck=nck

The WHO's definition of pertussis overestimates what pertussis normally looks like in terms of "length of cough" and whatnot...which is why the "85% effective" figure is probably way off. So until someone does an effectiveness study where they culture every single person for every cold/cough symptom...we don't even know what's going on there.

[amnesiac]

No I haven't read that one. Neither have I read the more recent ones linking to it.

[mamakay]

Originally Posted by amnesiac

No I haven't read that one. Neither have I read the more recent ones linking to it.

Read that one and think about what it means in terms of pertussis transmission.

There's also some really weird stuff going on with vax immunity and this one pertussis toxin called "ACT". Have you read anything about that?

[amnesiac]

It's not saying much to me in terms of when the illness is transmissible. It is saying that the case definition misses people who are infected & therefore the efficacy studies that use that case definition may be inaccurate.

Don't know anything juicy about ACT except that it isn't a vaccine component. Honestly I haven't read anything about pertussis immunity in many years.

[mamakay]

It's not saying much to me in terms of when the illness is transmissible. It is saying that the case definition misses people who are infected & therefore the efficacy studies that use that case definition may be inaccurate.

But it means we have no way of knowing if the vaccine does anything to alleviate symptoms in the first few weeks, when pertussis is the most contagious.

Don't know anything juicy about ACT except that it isn't a vaccine component. Honestly I haven't read anything about pertussis immunity in many years.

I'll find it again. It's bizarre.

[amnesiac]

I think that's exactly why Sanofi includes their little disclaimer - because they don't know how it really impacts that time period. What makes you say that's when it's most contagious?

[mamakay]

Here's the stuff about ACT...

First...what it is and what it does:

http://iai.asm.org/cgi/content/abstr...e2=tf_ipsecsha

Proliferation of Bordetella pertussis in the lungs of infant mice challenged by the intranasal route was examined. The bacteria rapidly proliferated in the lungs of mice challenged with a sublethal dose of a wild-type strain (BP338) or a filamentous hemagglutinin mutant (BPM409) from 500 at day 0 to 10(7) at day 15. The infection cleared in about 40 days. Pertussis toxin-deficient mutant BP357 gave a similar profile; however, the number of bacteria recovered was slightly reduced, suggesting that pertussis toxin is not essential for bacterial growth in the lungs. In contrast, adenylate cyclase toxin mutant BP348 was rapidly cleared from the lungs, with no viable bacteria remaining 10 days postchallenge, suggesting that the adenylate cyclase toxin is a colonization factor required for the bacteria to initiate infection.

Now some weirdo vax immunity stuff...

http://www.journals.uchicago.edu/CID...997378209Guest

The ELISA values of antibody to ACT in convalescent-phase
serum samples from previously vaccinated or unvaccinated
children with pertussis due to B. pertussis or B. parapertussis
infections are presented in table 2. In unvaccinated children,
the serum GMTs after pertussis due to B. pertussis or B. parapertussis
infections were elevated: 872 EU/mL and 512 EU/
mL, respectively (48- and 28-fold greater than the GMTs in
unvaccinated infants). Only 1 of the subjects, an 8-month-old
infant, had a low titer in the convalescent-phase blood sample
(titer, 16 EU/mL). In contrast, the GMTs in convalescent-phase
serum samples obtained from subjects in whom vaccination
had failed were only slightly elevated. The GMT in the serum
samples obtained from subjects for whom DTP () vaccine failed
was 92 EU/mL, and it was 49 EU/mL in the serum samples of
subjects for whom DTaP (Lederle/Takeda) vaccine failed (5-
and 3-fold greater than the GMT in serum samples obtained
from unvaccinated infants).

~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Of particular
interest is the lack of a significant ACT antibody response
in children for whom the DTP or DTaP vaccines failed. This
induced tolerance is intriguing and may be due to the phenomenon
called “original antigenic sin” [22]. In this phenomenon,
a child responds at initial exposure to all presented epitopes
of the infecting agent or vaccine. With repeated exposure
when older, the child responds preferentially to those epitopes
shared with the original infecting agent or vaccine and can be
expected to have responses to new epitopes of the infecting
agent that are less marked than normal. Because both vaccines
contained multiple antigens (i.e., PT, FHA, PRN, and fimbriae),
the patients who had been vaccinated responded to the antigens
that they had been primed with and did not respond to the
new antigen (i.e., ACT) associated with infection.

Strange, huh?

Have you read about phagocytosis (or lack thereof) in vax sera? Something about vaccine immunity inhibits phagocytosis as often as it helps it.
I'll find you that, too, if you want...

[mamakay]

About the infectious period...



http://www.drlera.com/bacterial_dise...ping_cough.htm

Whooping Cough (Pertussis)

Information from CDC

Infectious period

Highly infectious when the ‘cold-like’ symptoms occur in the early stages. Without treatment, a person is infectious for the first three weeks of coughing. With appropriate antibiotic therapy, the person is no longer infectious to others five days after starting antibiotics.

[amnesiac]

But there's no citation for that statement. When we do investigations the period of communicability isn't counted until the onset of cough, which is why I'm curious.

[mamakay]

Here's an australian gov site that says the same thing. (word for word)
http://www.dh.sa.gov.au/pehs/Immunis...acts-oct04.pdf

Infectious period
(time during which an infected person can infect others)
Pertussis is highly infectious when the “cold-like”
symptoms occur in the early stages. Without
treatment, a person is infectious for the first three
weeks of coughing.

Here's what the pink book says:

http://www.cdc.gov/vaccines/pubs/pin...loads/pert.pdf

The first stage, the catarrhal stage, is characterized by the
insidious onset of coryza (runny nose), sneezing, low-grade
fever, and a mild, occasional cough, similar to the common
cold.

Communicability
Pertussis is highly communicable, as evidenced by secondary
attack rates of 80% among susceptible household contacts.
Persons with pertussis are most infectious during the
catarrhal period and the first 2 weeks after cough onset (i.e.,
approximately 21 days).

[amnesiac]

So pretty much anytime they're oozing or spraying they're contagious. I don't think any real basis exists to distinguish relative contagiousness of each of those 2 phases.