There are some claims that the ongoing randomised trial of Daily Contact Testing (DCT) vs blanket quarantine/isolation in schools for cases of #COVID19 is "unethical"

Here is a short thread on why that is completely wrong

Randomised trials are indicated (ethical) when we have "equipoise", meaning we can't be sure which of some options is better

We want to get the best of all outcomes, e.g. a pill which is really good at treating mild coughs but frequently causes cancer is not good overall

For COVID-19 cases in schools, we know that we want to avoid transmission, but we also know that children missing school is harmful

There is equipoise as to whether the best of *all outcomes* is blanket quarantining of bubbles, or doing DCT

But wait, there's more

Imagine you are a 15yo sent home with your entire year group because of a case in another class

Your parents don't have to isolate, so off they go to work

Do you:
A) Stay home all day like you're supposed to
B) Go and see all your mates who are also not in school

Also in this scenario, if you are a 15yo asymptomatic positive case you might never find out

You could infect your parents, who go to work and don't realise until they are symptomatic (too late)

The chain of infection continues

Now imagine instead, you are the same 15yo doing daily tests

You test positive within a few days, and immediately you and your family all self isolate

Chain of transmission broken before your family infect others

So, there are plausible reasons why DCT might not only minimise time off school, but also be BETTER at interrupting transmission

This might not work at all, and blanket isolation/quarantine may be much more effective

But we have absolutely no idea

That's why we do trials

I am genuinely proud of the UK for investing huge resources into answering some of these questions, rather than just implementing interventions with no idea how effective that might be (although we are doing that too...)

The world will be eager to see the results


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More from @apsmunro

3 Jun
I've spent the last year running #COVID19 vaccine trials, and am leading one now as part of my PhD

I've spoken to A LOT of people about these vaccines!

If you ever feel confused about the vaccines against #COVID19 , hopefully this is the thread for you

We'll keep it simple!💉
Vaccines work by using your adaptive immune system (the part which remembers bugs) which is made up of 2 major parts:

- Humoral: Cells make antibodies to tag/attack bugs
- Cellular: Cells which directly recognise and attack/kill bugs (mainly T cells)
Usually, your immune system would see a bug (often a virus or bacteria) and learns how to recognise it by remembering specific bits we call "antigens"

It makes lots of antibodies and cells against these antigens the first time it sees them, ready to fight next time they appear!
Read 24 tweets
24 May
Some decent data is now emerging regarding prolonged symptoms after acute #COVID19 infection in children

Fortunately the data looks reassuring 👍

Low prevalence of prolonged symptoms in children, especially when compared to a control group

Let's take a look!

First, a large serology screening study from Switzerland 🇨🇭

No difference between seropositive and negative children with symptoms beyond 4 weeks (~10%), and similarly very low rates of symptoms at 6 months (2 & 4%)…

Next, a study from the UK using ZOE data 🇬🇧

Very low rates of prolonged symptoms at 4 w (4.4%) and <2% beyond 2 months

Of note, severity of symptoms was worse in the comparator group who tested negative...!…

Read 5 tweets
19 May

The @CovBoost clinical trial is open for registration of interest!

What is the @CovBoost trial you say?

Let me tell you!

COV-Boost is a multi centre RCT for evaluating 3rd dose boosters against COVID-19

Which is most immunogenic?

Which have the best side effect profile?

Does it matter whether you had Pfizer or Oxford to start with?

We need to find out!

Who can take part?

We’re recruiting adults aged 30 and above who have had 2 doses of COVID-19 vaccine, with the first dose in January 2021 or in December 2020

If that’s you - please consider taking part!

Read 7 tweets
19 May
Not much time to tweet but this is important

Figures for hospitalisations and deaths for kids from COVID-19 should be treated with *extreme caution*

Incidental positive tests make up a big proportion - up to 40% in data from California…

Remember the paediatric wards in London supposedly filling up with children with COVID-19 last autumn?

Not only were they not very sick, a full 33% of them were admitted for something unrelated to COVID-19

They just happened to test positive…

Reports are of 600 child deaths from COVID-19 in the US, but no clarification of how many children died WITH COVID-19, or FROM COVID-19 (unlike adults, this is a big issue for kids data)

NB: The CDC estimates ~600 child deaths from flu annually…

Read 4 tweets
4 May
Three great new studies of COVID in children this week!

First, household transmission in Germany 🇩🇪

Contacts of PCR pos cases tested Serology

Children both less susceptible AND less infectious when index cases than adults…

Next COVID in children from in Hong Kong 🇭🇰

>300 children positive, only 3 cases acquired in School and all the rest in the household or from travel…

Finally, a household contact study from Israel 🇮🇱

Contacts tested with both PCR AND Serology (subset)

Children about half as susceptible to adults and nearly half as infectious…

Read 4 tweets
19 Mar
Great @bmj_latest study from OpenSAFELY

Despite schools being the only thing open for much of wave 2 in the UK, living w/ children associated with marginal increased absolute risk of COVID-19 infection/hospitalisation, and no increase in death…

The study compared hospital records of over 9mil adults <65yrs during wave 1 and wave 2, comparing those who lived with children (split by primary and secondary age) to those who don't

They adjusted for covariates such as deprivation, age, BMI, smoking, etc

Wave 1: No difference in outcomes, except much lower risk of death for people with children

Wave 2: Tiny increase risk in infection and hospitalisation for those living with children (smaller for young children), but same or lower risk of death from COVID-19 or any cause.

Read 7 tweets

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