Emily Oster

6 min Read Emily Oster

Emily Oster

Recommendations, and an Immunity Explainer

Emily Oster

6 min Read

As we all continue our quarantine journey, I thought I’d start here with a few recommendations which have been working for our family. And then, back to COVID. Today, I wanted to dive into the question of immunity.

Recommendations

COVID Immunity: What is the Deal?

Last weekend, the head of the World Health Organization suggested there was no reason to think that having had COVID once would mean you will not get it again. At the same time, countries are talking about “Immunity” passports for people who have already been infected. Sweden is engaged in a controversial strategy of allowing the virus to spread relatively widely, moving towards “herd immunity”. These all seem fundamentally at odds. If previous infection doesn’t mean immunity, what is an immunity passport? How can these things all be true?

As we all grapple with the epidemic, this seems both very important and very confusing. A big piece of the problem is there is a lot of uncertainty which will not be immediately resolved. Expert’s impressions about the relative probabilities of various possibilities differ. This is all reasonable. More troubling is when people make statements which seem like they are certain and, in fact, what they mean is more nuanced.

The truth here is nuanced. I thought an explainer was in order. (For a more technical version of at least some of this material, this Lancet piece is excellent).

Let’s step back. When you get a viral infection — any viral infection — your body fights it by producing antibodies. These are proteins which stick to and kill the virus. They come in various types, denoted by ending letters (IgM, IgG, etc) and each have slightly different functions and timing but, basically, they all fight the virus.

Once you recover from a virus, the antibodies stick around. They live to fight another day! So if your body (say) re-encounters that same virus immediately, you are ready for it. You can see why this would be sensible from an evolutionary standpoint: people wouldn’t survive very long in a high disease environment (read, all of human history) if they were immediately reinfected with viruses.

In other words, these antibodies confer some “immunity”.

Antibodies are also how vaccines work. When you (or your kid) get the measles vaccines, they are getting a weakened form of the measles virus which prompts the body to produce antibodies against measles. If your child then encounters the real measles virus out in the world, they already have the antibodies to fight it off and will not get sick.

The basic science here is not in debate. Just like measles, the flu, chicken pox, etc, etc, in the case of this coronavirus (which is technically called SARS-COV-2) people who get it and recover have antibodies to it. And just like with those other viruses, you can test for these antibodies.

How? One option is you can use a very simple test — a quick finger stick of blood — and see if people have any antibodies at all. Or you can use a more involved test with more blood — and these are still being rolled out — to figure out how much of these antibodies you have.

Also not up for debate is the question of whether, in general, antibodies confer some immunity. They do. If you have antibodies to SARS-COV-2 you are somewhat protected from getting it.

However, there is a tremendous amount of uncertainty around the details. And that’s where the devil is.

There is a lot of variation across viruses in how long antibodies (and therefore immunity) stick around. Chicken pox antibodies seem to confer very long term immunity; flu much less so.

There is variation across viruses in how much antibody you need to not be infected. Generally higher rates of antibodies confer more protection but the “threshold” isn’t consistent.

There is variation across people in their degree of antibody response — some people produce more than others. Some of this may relate to severity of infection. In the case of COVID-19, a lot of people are infected without symptoms. They may have a less significant antibody response (or they may not! We don’t know).

Aggregating up, we also do not know what share of people would need to have antibodies to keep the virus out of the overall population (this is what is known as “herd immunity”). That number varies based on how infectious the virus is — how fast it spreads — something we also do not know perfectly. For measles (for example) it’s so infectious that you need a huge share of people to be immune (estimates suggest around 90%) in order to develop herd immunity. For the flu, which spreads much less quickly, this is under 50%.

With existing viruses, we know a lot of answers here because they’ve been carefully studied. You can use lab data, or evidence across populations, to answer questions about measles immunity. With a new virus, we still need to learn all of this. We cannot be certain about the answers to most of these question in the context of the virus causing this pandemic, SARS-CoV-2

However, it’s misleading to say we are flying totally blind. It makes sense that we could learn something about SARS-CoV-2 from other, (genetically) related, coronaviruses. SARS-COV-2 is closely related to SARS-CoV, the coronavirus that caused SARS in 2002 (the original SARS) and other coronavirses. Based on those, we do expect immunity among individuals who have been sick. This immunity seems to persist in SARS patients at least through a year out from symptoms (long term studies are somewhat lacking). Data on the also related Middle East Respiratory Syndrome (MERS) suggests a perhaps longer period of immunity.

These other viruses and our general analysis of the speed of viral spread suggest herd immunity may arise at around 60% infection rate. If we learn that the virus is more infectious than we thought, this may go up.

Putting this all together, I think what the head of the WHO was trying to say is that there is a lot of uncertainty. For a bunch of reasons, we do not want to give people the impression that if they have evidence on antibodies on a finger prick test they are totally protected from the virus. Nor do we want to give policymakers the sense that if exactly 62% of their population shows antibodies, they are good to go on opening the economy without restrictions.

On the other hand, suggesting that there is “no immunity” to this virus is also misleading. It is theoretically possible that we will learn that SARS-COV-2 is unlike all related viruses and infection does not confer any immunity but that is incredibly unlikely. We have to make decisions based on some uncertainty here, based on the best evidence we have. There is value in knowing antibody levels in individuals and populations, because our best information suggests that they will confer some immunity.

As always, it comes down to: More Testing. Better Testing. More Testing. More data.

Covid-19 rapid antigen tests arranged in a pattern on a yellow background.

Feb 20 2023

12 min read

COVID-19: Where to Go from Here

A long-term view of the virus

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Oct 20 2022

9 min read

Should You Get the Bivalent Booster?

The latest on the risks and benefits of COVID vaccines boosters for older adults, pregnant people, and kids

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A line graph with pink, yellow, and blue dots representing life's ups and downs.

Aug 16 2022

3 min read

Wins, Woes, and Doing It Again

We have our first story from a dad! And it’s a good one. 10/10 —Girl Dad with Confidence Growing by Read more

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Covid-19 rapid antigen tests arranged in a pattern on a yellow background.

Aug 15 2022

8 min read

Updated CDC Guidelines for School and Child Care

NO QUARANTINES!!!

Emily Oster

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Do you brand things a certain way to get your kid to accept it? Like calling carrots “rabbit popsicles”? Or telling them to put on their “super speed socks” in the morning? Share your rebrands in the comments below! You never know who you might be helping out 👇

#emilyoster #funnytweets #relatabletweets #parentingjokes #kidssaythedarndestthings

Do you brand things a certain way to get your kid to accept it? Like calling carrots “rabbit popsicles”? Or telling them to put on their “super speed socks” in the morning? Share your rebrands in the comments below! You never know who you might be helping out 👇

#emilyoster #funnytweets #relatabletweets #parentingjokes #kidssaythedarndestthings
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Have you ever panic-googled a parenting question when everyone else is asleep? If so, you’re not alone. 

Today is the first episode of a new biweekly series on my podcast: Late-Night Panic Google. On these mini-episodes, you’ll hear from some familiar names about the questions keeping them up at night, and how data can help. First up: @claireholt!

Listen and subscribe to ParentData with Emily Oster in your favorite podcast app 🎧

#parentdata #emilyoster #claireholt #parentingstruggles #parentingtips #latenightpanicgoogle

Have you ever panic-googled a parenting question when everyone else is asleep? If so, you’re not alone.

Today is the first episode of a new biweekly series on my podcast: Late-Night Panic Google. On these mini-episodes, you’ll hear from some familiar names about the questions keeping them up at night, and how data can help. First up: @claireholt!

Listen and subscribe to ParentData with Emily Oster in your favorite podcast app 🎧

#parentdata #emilyoster #claireholt #parentingstruggles #parentingtips #latenightpanicgoogle
...

Sun safety is a must for all ages, especially babies! Here are my tips for keeping your littlest ones protected in the sunshine:
☀️ Most importantly, limit their time out in hot weather. (They get hotter than you do!)
☀️ Keep them in the shade as much as possible when you’re out.
☀️ Long-sleeve but lightweight clothing is your friend, especially on the beach, where even in the shade you can get sunlight reflecting off different surfaces.
☀️ If you want to add a little sunscreen on their hands and feet? Go for it! But be mindful as baby skin tends to more prone to irritation.

Comment “Link” for a DM to an article on the data around sun and heat exposure for babies.

#sunsafety #babysunscreen #babyhealth #parentdata #emilyoster

Sun safety is a must for all ages, especially babies! Here are my tips for keeping your littlest ones protected in the sunshine:
☀️ Most importantly, limit their time out in hot weather. (They get hotter than you do!)
☀️ Keep them in the shade as much as possible when you’re out.
☀️ Long-sleeve but lightweight clothing is your friend, especially on the beach, where even in the shade you can get sunlight reflecting off different surfaces.
☀️ If you want to add a little sunscreen on their hands and feet? Go for it! But be mindful as baby skin tends to more prone to irritation.

Comment “Link” for a DM to an article on the data around sun and heat exposure for babies.

#sunsafety #babysunscreen #babyhealth #parentdata #emilyoster
...

I’m calling on you today to share your story. I know that many of you have experienced complications during pregnancy, birth, or postpartum. It’s not something we want to talk about, but it’s important that we do. Not just for awareness, but to help people going through it feel a little less alone.

That’s why I’m asking you to post a story, photo, or reel this week with #MyUnexpectedStory and tag me. I’ll re-share as many as I can to amplify. Let’s fill our feeds with these important stories and lift each other up. Our voices can create change. And your story matters. 💙

#theunexpected #emilyoster #pregnancycomplications #pregnancystory

I’m calling on you today to share your story. I know that many of you have experienced complications during pregnancy, birth, or postpartum. It’s not something we want to talk about, but it’s important that we do. Not just for awareness, but to help people going through it feel a little less alone.

That’s why I’m asking you to post a story, photo, or reel this week with #MyUnexpectedStory and tag me. I’ll re-share as many as I can to amplify. Let’s fill our feeds with these important stories and lift each other up. Our voices can create change. And your story matters. 💙

#theunexpected #emilyoster #pregnancycomplications #pregnancystory
...

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio!

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio! ...

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio!

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio! ...

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio!

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio! ...

Is side sleeping important during pregnancy? Comment “Link” for a DM to an article on whether sleep position affects pregnancy outcomes.

Being pregnant makes you tired, and as time goes by, it gets increasingly hard to get comfortable. You were probably instructed to sleep on your side and not your back, but it turns out that advice is not based on very good data.

We now have much better data on this, and the bulk of the evidence seems to reject the link between sleep position and stillbirth or other negative outcomes. So go ahead and get some sleep however you are most comfortable. 💤

Sources:
📖 #ExpectingBetter pp. 160-163
📈 Robert M. Silver et al., “Prospective Evaluation of Maternal Sleep Position Through 30 Weeks of Gestation and Adverse Pregnancy Outcomes,” Obstetrics and Gynecology 134, no. 4 (2019): 667–76. 

#emilyoster #pregnancy #pregnancytips #sleepingposition #pregnantlife

Is side sleeping important during pregnancy? Comment “Link” for a DM to an article on whether sleep position affects pregnancy outcomes.

Being pregnant makes you tired, and as time goes by, it gets increasingly hard to get comfortable. You were probably instructed to sleep on your side and not your back, but it turns out that advice is not based on very good data.

We now have much better data on this, and the bulk of the evidence seems to reject the link between sleep position and stillbirth or other negative outcomes. So go ahead and get some sleep however you are most comfortable. 💤

Sources:
📖 #ExpectingBetter pp. 160-163
📈 Robert M. Silver et al., “Prospective Evaluation of Maternal Sleep Position Through 30 Weeks of Gestation and Adverse Pregnancy Outcomes,” Obstetrics and Gynecology 134, no. 4 (2019): 667–76.

#emilyoster #pregnancy #pregnancytips #sleepingposition #pregnantlife
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My new book, “The Unexpected: Navigating Pregnancy During and After Complications” is available for preorder at the link in my bio!

I co-wrote #TheUnexpected with my friend and maternal fetal medicine specialist, Dr. Nathan Fox. The unfortunate reality is that about half of pregnancies include complications such as preeclampsia, miscarriage, preterm birth, and postpartum depression. Because these are things not talked about enough, it can not only be an isolating experience, but it can also make treatment harder to access.

The book lays out the data on recurrence and delves into treatment options shown to lower risk for these conditions in subsequent pregnancies. It also guides you through how to have productive conversations and make shared decisions with your doctor. I hope none of you need this book, but if you do, it’ll be here for you 💛

#pregnancy #pregnancycomplications #pregnancyjourney #preeclampsiaawareness #postpartumjourney #emilyoster

My new book, “The Unexpected: Navigating Pregnancy During and After Complications” is available for preorder at the link in my bio!

I co-wrote #TheUnexpected with my friend and maternal fetal medicine specialist, Dr. Nathan Fox. The unfortunate reality is that about half of pregnancies include complications such as preeclampsia, miscarriage, preterm birth, and postpartum depression. Because these are things not talked about enough, it can not only be an isolating experience, but it can also make treatment harder to access.

The book lays out the data on recurrence and delves into treatment options shown to lower risk for these conditions in subsequent pregnancies. It also guides you through how to have productive conversations and make shared decisions with your doctor. I hope none of you need this book, but if you do, it’ll be here for you 💛

#pregnancy #pregnancycomplications #pregnancyjourney #preeclampsiaawareness #postpartumjourney #emilyoster
...

We are better writers than influencers, I promise. Thanks to our kids for filming our unboxing videos. People make this look way too easy. 

Only two weeks until our book “The Unexpected” is here! Preorder at the link in my bio. 💙

We are better writers than influencers, I promise. Thanks to our kids for filming our unboxing videos. People make this look way too easy.

Only two weeks until our book “The Unexpected” is here! Preorder at the link in my bio. 💙
...

Exciting news! We have new, high-quality data that says it’s safe to take Tylenol during pregnancy and there is no link between Tylenol exposure and neurodevelopmental issues in kids. Comment “Link” for a DM to an article exploring this groundbreaking study.

While doctors have long said Tylenol was safe, confusing studies, panic headlines, and even a lawsuit have continually stoked fears in parents. As a result, many pregnant women have chosen not to take it, even if it would help them.

This is why good data is so important! When we can trust the data, we can trust our choices. And this study shows there is no blame to be placed on pregnant women here. So if you have a migraine or fever, please take your Tylenol.

#tylenol #pregnancy #pregnancyhealth #pregnancytips #parentdata #emilyoster

Exciting news! We have new, high-quality data that says it’s safe to take Tylenol during pregnancy and there is no link between Tylenol exposure and neurodevelopmental issues in kids. Comment “Link” for a DM to an article exploring this groundbreaking study.

While doctors have long said Tylenol was safe, confusing studies, panic headlines, and even a lawsuit have continually stoked fears in parents. As a result, many pregnant women have chosen not to take it, even if it would help them.

This is why good data is so important! When we can trust the data, we can trust our choices. And this study shows there is no blame to be placed on pregnant women here. So if you have a migraine or fever, please take your Tylenol.

#tylenol #pregnancy #pregnancyhealth #pregnancytips #parentdata #emilyoster
...

How many words should kids say — and when? Comment “Link” for a DM to an article about language development!

For this graph, researchers used a standardized measure of vocabulary size. Parents were given a survey and checked off all the words and sentences they have heard their child say.

They found that the average child—the 50th percentile line—at 24 months has about 300 words. A child at the 10th percentile—near the bottom of the distribution—has only about 50 words. On the other end, a child at the 90th percentile has close to 600 words. One main takeaway from these graphs is the explosion of language after fourteen or sixteen months. 

What’s valuable about this data is it can give us something beyond a general guideline about when to consider early intervention, and also provide reassurance that there is a significant range in this distribution at all young ages. 

#cribsheet #emilyoster #parentdata #languagedevelopment #firstwords

How many words should kids say — and when? Comment “Link” for a DM to an article about language development!

For this graph, researchers used a standardized measure of vocabulary size. Parents were given a survey and checked off all the words and sentences they have heard their child say.

They found that the average child—the 50th percentile line—at 24 months has about 300 words. A child at the 10th percentile—near the bottom of the distribution—has only about 50 words. On the other end, a child at the 90th percentile has close to 600 words. One main takeaway from these graphs is the explosion of language after fourteen or sixteen months.

What’s valuable about this data is it can give us something beyond a general guideline about when to consider early intervention, and also provide reassurance that there is a significant range in this distribution at all young ages.

#cribsheet #emilyoster #parentdata #languagedevelopment #firstwords
...