Thread by @apsmunro

The worlds biggest study of post acute #COVID19 symptoms in children is out as a pre-print - the CLoCK study!

Fortunately results are very reassuring regarding symptom frequency and impact

Some important lessons, let's take a look 🧵

1/
bbc.co.uk/news/health-58…

The study compared people who tested positive for SARS-CoV-2 to those who tested negative

They looked at symptoms at the time of testing, and then 3 months later

The differences are then presumably due to one group having covid

They surveyed children aged 11 - 17

2/

What did they find?

At time of testing, 35% of test positives had symptoms compared to only 8% of test negatives

Astoundingly, 3 months later 67% of test positives had any symptoms, and *53% of test negatives* had symptoms

3/

This is why studies of persistent symptoms after covid which don't have a control group are almost completely useless

Over HALF of children who didn't have SARS-CoV-2 had symptoms 3 months later (despite only 8% having symptoms at baseline!)

These symptoms are SO common

4/

More symptoms were found in the positive group, which is what we would expect

These were most commonly tiredness, headaches, loss of smell, and shortness of breath

Test positives were more likely to have multiple (3+ symptoms) too (30% v 16%)

5/

Interestingly, there was almost no difference in any score on mental health, well being or quality of life assessments (including fatigue) for those who tested positive vs negative

There were small differences in problems with mobility and pain/discomfort

6/

As the paper notes, strikingly 40% of test positives and 39% of test negatives reported feeling "worried, sad or unhappy" on the QoL questionnaire

Whatever else is going on, our children and young people are not in a good place currently

7/

The team identified a cluster of children who had several symptoms ("class 2")

Risk factors for being in this cluster included testing positive for covid, being female, being older, and having worse pre-test physical and mental health

8/

Some important biases:

Responder bias: 13% of people invited to the survey responded. Families with something to report are more likely to respond
Detection bias: only children who got tested enter the study, and we know many with covid don't get tested due to mild symptoms

9/

These are important as the study will likely overestimate the proportion of children infected with covid who go on to have longer symptoms

Fortunately, it appears even for those who do, the impact on life is very limited for most, compared to children without covid

10/

We do know there are some children who do go on to have more debilitating symptoms after #COVID19, and they need support and help to recover

Fortunately, this appears rare

Most children recover quickly, and ongoing symptoms do not appear to significantly impair QoL

11/

Hopefully we can move forward soon from putting all manner of symptoms into a single basket, and separate out distinct syndromes (post viral cough, anosmia, post viral fatigue, autoimmune etc) to give each of them specific focus

Link to study:
researchsquare.com/article/rs-798…

12/end