Looking for reassurance. Can anyone explain why a 40 pound 4-year-old can get the same covid vaccine as a 15 pound 6-month-old?

[aussiewife]

I have a small baby (15 lbs) who is up to date on her regular vaccinations up to 6 months. My partner and I are both vaxxed & boosted with Pfizer, and we’re planning on having our daughter vaccinated asap before she starts daycare in August. I just feel nervous because she’s so small and young. I’ve seen some really well-informed discussions on this sub so I was hoping someone could help put my mind at ease about this.

Also, I’ve read that Moderna starts working quicker than Pfizer because it contains more RNA, but that the side effects are a bit more intense than with Pfizer. I don’t want to be in a situation where we have to rush to the hospital because our baby has a really high fever from the shot. But at the same time, I want her to have the most effective protection against covid.

A final concern I have is this hypothetical scenario where the baby catches covid but we don’t realize it until the day or so after she gets her shot, and her symptoms are more extreme.

Basically, I’m an anxiety filled first time mom looking for a little reassurance and knowledge. Thanks in advance for any insights.

 

[shahab]

@aussiewife this is a great question! as others have said, vaccines are not dosed by weight like drugs are. the vaccines themselves do not have any intrinsic pharmacological effects but rather trigger your baby’s immune system to produce those effects.

we have to rush to the hospital because our baby has a really high fever from the shot

this is a pretty unlikely scenario. now that your baby is 6 months you don’t have to be as hypervigilant about fever as you were when she was a newborn. she may get a fever from the vaccine but it’s a positive sign that her immune system is working as it should! the human body is very, very unlikely to produce temperatures harmful to itself unless it’s a malignant hyperthermia reaction (harmful side effect of some drugs but NOT the vaccine). just stock up on some fever-reducers, but you really shouldn’t even be giving them unless she’s super uncomfortable from a fever (again, the fever is a positive sign!)

 

[churchfreak1974]

@shahab This is a great answer. You can also reach out to your pediatrician beforehand and ask specifically how to treat low-grade vs high fever after vaccine, and when to call them or go to the hospital. They're going to be your best resource in those matters. And remember, they give a lot of vaccines (not just covid!)

 

[matt0007]

@shahab Yes thank you for your answer!!! Other replies saying, “the same reason a 90 lb person and 300 lb person can have have the same vaccine” were not answering the question for me haha …. Because like … why can they have the same vaccine? Same question? Anyway thank you for answering.

 

[aussiewife]

@shahab Thank you for your answer

 

[su1]

@aussiewife Fever-reducing drugs like Tylenol ARE weight based so make sure you get the correct dosage from you pediatrician in the case of fever for both your kiddos!

 

[shahab]

@aussiewife happy to help!! I used to work as an MA in a pediatrician’s office and spent so much of my day answering questions about vaccines

 

[electron7]

@shahab Just curious: has it also to do with the fact that the corona virus would infect every victim with the same "dose". So everyone has to get trained (vaccinated) with the same dose to be prepared for the real virus?

 

[shahab]

@electron7 actually, not every covid patient is infected with the same dose! if you’re constantly exposed to someone with covid over a longer period of time you’re going to take on a higher amount of virus (called a viral load) than someone who’s briefly exposed. I read a lot back toward the beginning of the pandemic about how high viral loads were associated with much worse outcomes.

 

[electron7]

@shahab Correct but when exposed in the same way the virus doesn't care how old you are to infect you with a certain dose. It will infect a 6 monts old the same way as a 40 yo

 

[nikonguy72]

@aussiewife Same reason why a 300lb person can get the same vaccine as a 120lb person.

 

[slaphappie]

@aussiewife Vaccines work differently than drugs you take orally. Drugs you take orally get distributed thru the body and body size/weight affects the concentration in your blood/tissues. Vaccines basically get trafficked by immune cells from the injection site to the lymph node, then your immune system does its thing. Body weight doesnt affect this process much.

 

[wildflower1113]

@slaphappie Except it does bc when you dose sub q anything other than vaccines you dose them for weight still.

 

[slaphappie]

@wildflower1113 Things that have a mechanism of action related to the immune system? Or things that are meant to be distributed systemically?

 

[richboat]

@wildflower1113 Different things are different.

 

[katrina2017]

@aussiewife Same reason why I’m 140lb getting the same dose as people two to three times my weight. It’s about the immune response based on age, not weight.

 

[runako]

@katrina2017 Exactly this. My mother weighs 105 pounds, she’s a tiny thing. My husband is 6’2 and 240 pounds. They both got the same vaccine dose.

 

[busmcgusterblus]

@aussiewife For the same reason a 300 lb person can get the same one as a 100 lb person.

 

[kevonb129]

@busmcgusterblus And why Chihuahuas get the same dose as Great Danes

 

[dancequeen12]

@busmcgusterblus Exactly