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Your Healthy Family: Infectious disease expert addresses biggest concerns about COVID vaccine

Posted at 11:28 AM, May 13, 2021
and last updated 2023-02-23 13:53:50-05

Disclaimer: This is sponsored content. All opinions and views are of UCHealth and does not reflect the same of KOAA.

I recently got a question from a viewer about COVID-19 vaccine dosing. She asked me why a 103-pound woman gets the same dose of vaccine as a 300-pound man. Also, with the Pfizer COVID vaccine now approved for children 12 and older in the United States, parents perhaps might have the same question. I spoke with Dr. Michelle Barron, the senior medical director of infection prevention at UCHealth, to get the answer.

Dr. Barron says many drugs are generally dosed based on a person’s weight because that’s how those medicines work the best. “If you're taking a medication by mouth or by IV (intravenously), the idea is that you're trying to get a concentration into your bloodstream.”

When it comes to vaccines, they work differently - beginning with where they are injected, which is into a muscle instead of a vein, says Dr. Barron. “When you get a vaccine, the idea behind it isn't that you're giving it into the bloodstream. We give it in the arm typically because we’re trying to stimulate your immune system. The immune cells that we are trying to target do not live in your blood - some do - but they typically live beneath the surface of your skin.”

What might change from person to person when it comes to a vaccine is the length of the needle - based on someone's arm size – because the goal is to get the vaccine into the right part of the muscle to deliver the best response.

That’s why the Pfizer vaccine, now cleared for kids 12 and older, will be given in the same doses as other adults are getting.

Dr. Barron says parents, however, generally have other concerns if they are unsure about getting their kids vaccinated. “The biggest things I have been asked are: Can this impact their fertility long-term and concerns about the long-term effect.” The answers to both are no. “There is nothing in the testing that suggests either, in any of the data. The problem with this technology (mRNA) is that it’s not quite as new as people truly understand (or believe). It's been around for some time, and they've done a lot of investigations related to it. At the end of the day, part of our ability to open society for kids, so they can go to school and summer camp and be able to do all the things they want to do is having them get a vaccine. It allows those things to happen in a much freer fashion.”

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