Transcript for How is Johnson & Johnson’s COVID-19 vaccine different from others?
Exactly. Let's turn to chief medical correspondent Dr. Jen Ashton who has been collecting all of your medical answers. First question, why is the vaccine dosage the same for a 200-pound person versus a 100-pound person? I love the way this person asking the question is thinking. It's the pharmacology of drugs. It's oftentimes weight-based as most of us know, sometimes. Immune systems and vaccines work differently for the most part. The reason for that is the immune season only needs a little whiff of an infectious pathogen to multiple and magnify their response. So the only exception to this, really, is that older people's whose immune system can be, you - know, a little weaker, might need more. But for the rest of us, you know, we only need to show our immune system a little bit of something to have it go on an all-out priming attack. That was a great question. Now a non-covid-related questions. Is there a difference between lactose intolerance and a milk allergy? About 2% of the American population has a milk allergy. Lactose intolerance way more common. In some ways you can think of it as shades of gray on a spectrum, G.I. Symptoms. But at the core they are very different. Again, a lot of people, by the way, whether it's with food or medication will kind of relay some symptoms, but that's not the same thing as a true allergy. If you feel you get some kind of G.I. Distress, which is the most common after having any kind of dairy, you may in fact be lacking that enzyme and you should speak to an allergist. You can submit your questions to Dr. Jen on her Instagram @drjashton.
This transcript has been automatically generated and may not be 100% accurate.