Emily Oster

5 min Read Emily Oster

Emily Oster

Follow-up Q&A: Your Top COVID Vaccine Questions

Emily Oster

5 min Read

If you missed my Q&A on Instagram Live today about vaccines for kids under five, you can watch it here or read the highlights below. I’m sharing these highlights with paid subscribers because I know that you may prefer this format.

As I’ve stated before, this isn’t about convincing people to vaccinate. Instead, I want to help you navigate the details of your vaccine planning in a way that works for you and your kid’s doctor. 

I started with the biggest questions that I’m hearing from all of you:

Q: Moderna or Pfizer? 

  • The doses of these two vaccines are different. They’re both smaller than adults, but the relative size of the Moderna dose is larger.
  • With the larger dose, Moderna saw more efficacy faster; after two doses, researchers saw efficacy in terms of antibody levels that were comparable to adults and efficacy against symptomatic illness.
  • With Pfizer, the low dose meant that they didn’t see a sufficient antibody response after two shots. After the third shot, Pfizer saw a good antibody response in the whole cohort.
  • We are seeing more mild, regular vaccine side effects in the Moderna shot than in the Pfizer. There’s more evidence of some fevers, sore, arms, fatigue, crying. Pfizer saw very few, if any, side effects.
  • These are both safe and effective vaccines.

Q: What if my kid already had Covid?

  • COVID is a dose of immunity the same way the vaccine is a dose of immunity, providing the ability to fight future infections.
  • We have seen in adults that hybrid immunity — having had COVID and the vaccine in either order — tends to be more protective than either of those two things alone.
  • The distance between vaccines can also promote more antibody response.
  • Based on what we see in adults, some break between having had COVID and vaccination seems like it’s likely a good idea, perhaps in a range of 90 days.

Q: What if my kid is almost five?

  • If you wait until your kid is five and they get Pfizer, that’s a bigger dose than the Pfizer for the two to five year olds. But the Moderna for two to five year olds is also a bigger dose than the Pfizer for two to five year olds.
  • So if you do Moderna now for your almost five year old, it’s going to be similar to doing the Pfizer later.

Q: How much time between doses?

  • In general, we have seen that longer time periods between doses have provoked a better immune response.
  • Pfizer landed on three weeks and Moderna landed on four to eight weeks. A lot of people are pushing towards eight weeks with the idea that that longer time between the doses is beneficial. But don’t ruin your vacation to get it exactly four weeks later — that is not an important thing.

Q: Should I wait for the fall?

  • What we know about these vaccines is that the protection against symptomatic illness fades (even though the protection against serious illness does seem to sustain for a longer period.)
  • I can see people waiting until the fall to vaccinate right before the school year starts.
  • However, if you want your two to five year old to have the maximum protection in the fall, you actually need to start vaccinating them now because of the timeframe.

I answered the following questions in a rapid-fire round:

Q: What about long COVID?

  • We don’t have a lot of evidence of long COVID in kids. It doesn’t seem like it’s as important as it is in adults.

Q: What about antibodies from breastmilk?

  • Breastmilk antibodies are indirect. The COVID vaccine antibodies are direct. They’re different. It’s not a substitute.

Q: Where can I find a vaccine?

  • For kids over three, there are some good vax finder websites and CVS is doing them in a lot of places.
  • You typically need to go to your pediatrician although some pediatricians have been reluctant to start doing this because of logistics.
  • We should all keep pushing people in government to get this together if they’re going to encourage people to vaccinate.

Q: What about quarantines?

  • I hope we see some relaxation in the quarantines given that the CDC has done that in general for people who are vaccinated.
  • We know sometimes the CDC doesn’t update their website immediately.

Q: Is there any protection after the initial dose?

  • Yes, the first dose is a push in the immune system. The second dose is another push.
  • When the Pfizer vaccine wasn’t efficacious after two doses, it wasn’t that they didn’t see any antibody response. They just didn’t see a response that was as big as it was in adults. And so that is why they needed the third dose.

Q: What about myocarditis? 

  • Myocarditis is a significant vaccine risk — not large, but statistically significant and pretty clearly related to vaccines in young adult men, particularly after the second dose and more so with Moderna than with Pfizer.
  • It’s not something that happens very frequently in small children, which is why we have not seen a discussion in this age group.
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