SM - Would you mind - Vax dosing

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SM - Would you mind - Vax dosing

Middle Roader
I've seen the issue of vax dosing come up several times (in several different areas) lately.  A friend also brought it up.  I posted in Babycenter and Cath helped me some.  But I was wondering if you had anything more to add/help.  Here is the BabyCenter post and my subsequent question:

"I have a friend that asked me about vax dosing.  She was told "that they give the same dose to an infant as they give to an adult" (her email).  I wrote back with the following:
While it is true that the dose is the same (on some) for an adult as for an infant, you have to ask yourself if the infant is getting an adult dose, or is the adult getting an infant dose.  For example: if you wanted to give [Son] a painkiller, you would give him infant tylenol.  If you were to take tylenol yourself, you'd probably opt for extra-strength adult tylenol.  But what if infant tylenol worked just as well for you (an adult) as it did for [Son]?  You would both be taking the same dose, but you would be taking a lesser dose, not [Son] taking too big a dose.  Does that make sense?
She replied with "What you said about tylenol dosage makes sense, but then does that mean I'm taking too much tylenol, or he's getting too much vaccine?"
I'm not sure what to tell her on that.  Anyone have any reasearch/medical info that I could point her to?"

"Would you happen to know which vaxs are the same [dose], which are less for the infant and which are more for the infant?"
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Science Mom
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Middle Roader wrote
While it is true that the dose is the same (on some) for an adult as for an infant, you have to ask yourself if the infant is getting an adult dose, or is the adult getting an infant dose.
You know this is bloody brilliant and quite correct for some of the vaccines received by infants and adults.

Middle Roader wrote
"Would you happen to know which vaxs are the same [dose], which are less for the infant and which are more for the infant?"
Yes.  Hep B is half the dose for infants as the adult dose.  The pertussis and diphtheria portions are actually higher for infants (DTaP) than for adults (Tdap) hence the capitol v. small letters.  Infants are naive to pertussis and diphtheria so they need a higher antigen concentration to achieve a protective antibody response.   MMR is the same volume dose for infants and for adults because again, infants are naive to the antigens and need to mount a robust response.  Whereas most adults have had an MMR already and another will allow them to mount an amnestic response.  Same with varicella although Zostavax (for shingles) has 10x the concentration as the infant/adult dose because of the lowered response in older people.  The same goes for IPV (polio).  So yes, adults are actually getting an infant dose of some vaccines rather than the other way around.  You can't look merely at the volume or concentration; you have to consider what is required for certain cohorts to achieve protection.

SM

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Re: SM - Would you mind - Vax dosing

Middle Roader
Thanks!  I just emailed my friend and we shall see if how I put it made sense to her.  One other thought that popped in my head while I was writing:

I've heard it said that an infant's immune system is immature, is that true?
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