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Alasdair Munro Profile picture
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29 Jan, 8 tweets, 4 min read
I've seen suggestions that the idea younger children might be less susceptible to infection with #COVID19 is a "myth", based on children just not being tested enough

That is untrue!

Whilst it's true children are under tested, this is not where this idea came from!

1/8
It comes from household contact tracing studies

When someone in a home is identified as being infected, the other members of the house are tested to see if they are infected

It's a useful experiment as everyone at home gets very similar exposure

2/8
Some early studies did only test contacts with symptoms, but actually most large studies since then have tested ALL close contacts REGARDLESS of symptoms

Here are just a handful

Zhang
science.sciencemag.org/content/368/64…

Jing
thelancet.com/journals/lanin…

Somekh
journals.lww.com/pidj/Fulltext/…

3/8
Rosenburg
academic.oup.com/cid/article/71…

Sun
science.sciencemag.org/content/early/…

Van der Hoek
ntvg.nl/artikelen/de-r…

Lewis
academic.oup.com/cid/advance-ar…

ALL of these found young children to be around half as susceptible to infection as adults

4/8
There are many studies on this issue, which is why even better than looking at individual (even large) studies, is to look at many in combination - meta analyses

There are several; ALL of which found young children around half as susceptible as adults

5/8
Madewell
jamanetwork.com/journals/jaman…

Zhu
academic.oup.com/cid/advance-ar…

Goldstein
dx.doi.org/10.1093/infdis…

Viner
jamanetwork.com/journals/jamap…

6/8
Regarding epidemiology and under testing, even infection surveys who test populations regardless of symptom status in England have found far lower rates of infection than you should predict, given children much higher number of contacts than adults

7/8
So there you have it!

Another myth about COVID-19 in children busted 💥

It's never cased closed, but this is where the available evidence leaves us for the moment.

8/8

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More from @apsmunro

Alasdair Munro Profile picture
9 Jan
I think people find it hard to understand the deal with kids reduced susceptibility to #COVID19 and what it means for schools etc

I thought I’d share a little analogy which helps me conceptualise it

Let’s imagine #COVID19 is rain... 🌧

1/8
Everyone wants to stop getting wet

Adults are just dressed normally 👦

Teens have a little hat on 🧢

Younger kids have got an umbrella ☂

2/8
When there is very little rain, you won’t notice much difference between how wet everyone is

When it starts raining a bit, you’ll notice the younger kids are less wet than adults

The teens may be just as wet as they spend more time out in the rain

3/8
Read 8 tweets
Alasdair Munro Profile picture
3 Jan
The current issue of #schoolclosures is so complex I am loathed to add my opinion to the twitter soup

Massive uncertainties✅
High stakes✅
Huge health trade offs✅
Opposing opinions ✅
Easy answers 🚫

I'll just add a few simple thoughts

1/9
Firstly, don't be fooled by twitter

It has the most shouty and polarised opinions only, the moderates have been largely hounded out

Both public and scientific opinion is almost certainly much more nuanced and balanced than this platform would fool you into believing

2/9
Next, advocating for widespread closure is a legitimate opinion in the current environment

Massive, uncontrolled community transmission and looming hospital capacity issues, with high prevalence of infections among children (esp teens) are a bad mix

3/9
Read 9 tweets
Alasdair Munro Profile picture
18 Dec 20
New findings from Swiss seroprevalence and an good opportunity to learn some more infectious disease epidemiology!

A similar prevalence in children aged 6 - 18 y (23%) than the adult population (~27%)

Lower in kids <6y (~15%) and over 65y (<15%)

What can we learn?

1/8
First, another lesson in age binning for kids (will we ever learn?)

6 - 18y is a weird age bin which I would not recommend

It hides big epidemiological differences

In fact, we have seen it in related data before...

2/8
The pre print of the first study from this team used age bin 5-19 y and reported no statistically different prevalence vs adults

medrxiv.org/content/10.110…

They changed for publication and found significantly lower prevalence in children <10y

thelancet.com/journals/lance…

3/8
Read 8 tweets
Alasdair Munro Profile picture
15 Dec 20
Here is a good lesson in basic epidemiology

This data is difficult to interpret in a number of ways:
1. There is no denominator, either of institutions or populations
2. It counts the number of outbreaks, not cases
3. It doesn't tell you who had the infections

This matters

1/5
An extreme example of why this is important from earlier this year

After lots of excitement about outbreaks in schools it turned out the median number of children involved was...

Zero

2/5
For some denominator context there are:

- 24,000 schools (9 million pupils) not inc. university
- 11,000 care homes (410,000 residents)
- 117 prisons (79,000 prisoners)
- 26,000 restaurants (many not/partially open)

We are comparing apples and oranges

Epidemiology 101

3/5
Read 5 tweets
Alasdair Munro Profile picture
11 Dec 20
It's time to clarify some things about children, schools and #COVID19 🧵

Summary: Young children seem significantly less susceptible, probably less likely to transmit. Less clear for teens. Schools mainly follow community trends, but secondary much higher risk than primary

1
The best way to determine susceptibility is through household contact tracing, as it controls for *exposure* - everyone gets more or less the same

There are many of these. Results vary, which we expect because infection is complicated

That's why we need to combine results

2
Here's 4 meta analyses; all find young children are much less susceptible than adults. Some that teens are too

Zhu (RR 0.6)
academic.oup.com/cid/advance-ar…

Goldstein (RR~0.5)
dx.doi.org/10.1093/infdis…

Viner (OR 0.41)
jamanetwork.com/journals/jamap…

Maidwell (RR ~0.5)
medrxiv.org/content/10.110…

3
Read 24 tweets
Alasdair Munro Profile picture
27 Nov 20
Really interesting pre print looking at school transmission in Northern Italy during the second surge

Suggests huge age dependant differences in risk of transmission in children in these settings (who would have guessed?!)

Let's take a look...

doi.org/10.1101/2020.1…

1/8
Detailed contact tracing of 43 cases
- 5 teachers
- 38 children

Whole classes tested regardless of symptoms, and swabbed a second time 10-14d later if the first was within 6 days of exposure

How much onward transmission?

2/8
Pre school (6 kids, 2 teachers) - 0/156 (0%)
Primary school (14 kids) - 1/266 (0.44%)
Secondary school (23 kids, 5 teachers) - 38/572 (6.64%)

Notice a pattern here?

3/8
Read 8 tweets

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