Dr Zoë Hyde Profile picture
Oct 3, 2020 33 tweets 11 min read
1. Updated thread on children & #COVID19 summarising the most recent research.

Summary: further evidence children & adults are equally susceptible & equally likely to transmit; school clusters are increasing; precautions needed in #schools.
#edutwitter #kinderen #Schulen #auspol
2. First, a recap, showing the risk associated with schools is largely dependent on community transmission.

If it is low (for example, at a level contact tracing can handle) then schools are low-risk (although precautionary measures are still needed).
3. Another large antibody study has shown that children and adults are similarly likely to be infected.

Importantly, young children and teenagers were just as likely to be infected.
4. This is similar to recent data from Italy.

In this household contact study in which people were tested for antibodies, there was no difference between very young children and older children.
5. This hasn't been seen in all studies. Here, younger children were less likely to be infected.

Circumstantial factors probably underlie such differences.

In this study, children were more likely to be infected if they were children of the index case.
6. Emerging data continue to suggest that children are as infectious as adults.
7. In the largest contact tracing study to date, a similar proportion of the contacts of child index cases and the contacts of adult index cases were infected.
8. This supports previous work from Italy, showing that the contacts of children were more likely to be infected than the contacts of adults.
9. Although it's not possible to say with certainty who infected whom in these studies, they strongly suggest that children do transmit the virus at clinically meaningful rates.
10. Even the youngest children can transmit the virus.

In this study, young children transmitted the virus to one-quarter of their household contacts.

Two out of three completely asymptomatic children transmitted the virus.
11. This is not surprising, because studies continue to show that children and adults have a similar viral load.

Here, the amount of viral RNA detected in swabs from symptomatic children was similar to (or higher than) that of adults.
12. Similar amounts of viral RNA were also detected in the swabs of children and adults in this study.

Importantly, no difference was seen in viral load between symptomatic and asymptomatic cases (which included both adults and children).
13. In this study of mostly adults, asymptomatic and symptomatic cases were also found to have a similar viral load.
14. This suggests children are likely to have a similar viral load to adults, even if they are asymptomatic.

This is important, because children appear much more likely to have an asymptomatic infection than adults.
15. In this antibody study of the children of healthcare workers in the UK, 50% of infections were asymptomatic.

Additionally, young (<10 years) and older (>=10 years) children were equally likely to have been infected (6.6% vs. 7.1%).
16. Infections in children may be hard to detect.

In this study from South Korea, 66% of symptomatic children with #COVID19 had symptoms which were mild enough to go unrecognised.

Only 9% were diagnosed at the time of symptom onset.
17. There may be little difference in symptoms between children with #COVID19, and those with other respiratory illnesses, as seen in this study.

The presence of fever or cough was not sufficient to distinguish between them.
18. This suggests it will be difficult to identify schoolchildren with #COVID19, and that schools will be an ideal environment for the virus to spread because of the number of close contacts that children have.
19. Although many cases in schools have been reported, there have been fewer superspreading events than was initially feared.

However, this doesn’t mean that children don't transmit the virus or that schools are a low-risk environment.
20. Two recent studies have shown that about 70% of infected people don’t seem to transmit the virus to anyone.

See the study below, and also the study described previously in point 7.
21. Exactly why is unclear. Possible reasons include the timing of infection, (lack of) opportunity to transmit, environmental factors that enhance transmission, and individual characteristics.
22. However, the frequency of transmission can be expected to be linked to the level of community transmission.

Higher levels of community transmission mean a greater probability of the virus being introduced to schools.
23. During a period of low community transmission in Germany, there was limited school transmission.

However, precautions were taken, including reducing class sizes by 50%, and regular ventilation of classrooms.
24. In the UK, the number of #COVID19 clusters in educational settings has surged since schools reopened.
25. Similarly, in France, clusters in schools and universities account for one-third of those currently under investigation.
26. Measures must be taken to reduce community transmission, and also to reduce the risk of transmission in schools.

At a minimum, this should include the use of face masks by staff and students (including both primary and high school students), and increasing ventilation.
27. Evidence continues to emerge of aerosol transmission being a major route.

This means that physical distancing - while important - is not sufficient.

Improving ventilation, wearing face masks, and reducing class sizes (if possible) are key.
28. There's growing evidence that masks protect the wearer from becoming infected, as well as preventing onward transmission.

Importantly, the kind of mask doesn't seem to matter too much, but it does have to be worn consistently.
29. If a school-aged child can safely wear a mask, they should.

Many Asian countries already require schoolchildren to wear masks, such as Singapore.

It is a simple intervention with minimal, if any, harms, as the Asian experience has shown.
30. On the other hand, if children are told they do not need to wear a mask in school and that they are unlikely to transmit the virus there, how can we expect them to behave outside school?

It seems unlikely they will follow precautionary measures. Advice must be consistent!
31. Even though children are far less likely than adults to become seriously ill, they can transmit the virus.

If we want to control the virus, we can't overlook the role of children in transmission.
32. We can't ignore any section of the population.

The virus doesn't remain confined to specific age groups.

In the US, a rise in cases in young adults was shown to precede cases in older people by about 9 days on average.
33. Schools remain an overlooked site of risk in many countries in this pandemic.

But guidelines to improve school safety have been developed.

If these guidelines (or those of a higher standard) aren't yet implemented in your region, ask why not.

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More from @DrZoeHyde

Jan 1
And now for something completely different.

Someone I know is a musician & recently released their first album. I think it’s pretty cool, and if you like rock, maybe you will too. 🤘🎸

You can stream the album here: ditto.fm/blonde-zombie-…

Read on to see reviews. 🧵
Australia’s The Hard Rock Show called it “a really good, solid album - well worth your time.”
Germany’s Hellfire-Magazin rated the album 7.5 out of 10.

🇩🇪 hellfire-magazin.de/cross-eyed-lov…

🇬🇧 🇺🇸 …w-hellfire--magazin-de.translate.goog/cross-eyed-lov…
Read 5 tweets
Jan 1
A representative survey of US adults in mid-2022 found that 7% had long COVID (4-week definition; using questions developed by the UK’s Office for National Statistics).

One-quarter of these people said their daily activities were impacted “a lot”. 🧵
🔗 academic.oup.com/cid/advance-ar…
Around the same time in the UK, 2.8% of people aged 2 years and older were estimated to be living with long COVID.

🔗 ons.gov.uk/peoplepopulati…
But children are less likely to experience long COVID than adults, and the authors of the US study only surveyed adults.
Read 5 tweets
Dec 29, 2022
I've not commented on this study so far, because it's uncertain what the findings mean. But I've seen some commentary that's definitely wrong and causing a lot of unnecessary concern. Further study is needed, but here's why I don't think people should be worried. 🧵
First, this isn't a phenomenon specific to mRNA vaccines or even to SARS-CoV-2/COVID-19.

It has been observed in combinations of whooping cough (pertussis), diphtheria, and tetanus vaccination.

These routine childhood vaccines are safe.
Second, this has nothing to do with IgG4-Related Disease, where IgG4 antibodies are thought to be an epiphenomenon. That is, they are an effect of the disease, not its cause.

IgG4 antibodies are associated with many things, including repeat infections.
Read 7 tweets
Dec 28, 2022
China’s decision to not just abandon zero COVID but to embrace an extreme “let it rip” policy is a catastrophe for both the Chinese people and the world. It will leave millions dead or disabled, badly damage the global economy, and may spawn dangerous new coronavirus variants. 🧵
The scale of the disaster is hard to imagine. There are an estimated 1,000,000 new infections and 5,000 deaths each day.

Not that you'd know this from the official statistics, which are no longer reported daily. The official death toll stands at 5,242.
The huge number of infections is reflected in the fact that China is exporting COVID-19 cases again. And not just exporting a few, either.
Read 14 tweets
Dec 28, 2022
A danger of giving up trying to control SARS-CoV-2 is that we increase the probability of a low likelihood but high impact event occurring. One such risk is recombination between SARS-CoV-2 & MERS. This could theoretically occur if someone were coinfected with these two viruses.
MERS has a case fatality rate of 36%, while SARS-CoV-2 is highly transmissible. A recombinant that shared some of these properties could potentially be catastrophic.

I stress this is only a theoretical risk, but scientists have warned of this possibility.
MERS hasn't gone away. According to the European Centre for Disease Prevention and Control, 6 MERS cases were recorded in 2022. All occurred in the Middle East, all were primary cases, and all but one of the infected people reported contact with a camel.
Read 4 tweets
Oct 22, 2022
An important new retrospective study of people who tested positive for COVID-19 in Ontario, Canada between the start of the pandemic and early 2021, has found that about 1% of these experience substantial post-infection morbidity. 🧵
In early 2022, about 45% of Canadians had a recent SARS-CoV-2 infection.

The authors write that over the next year, about 1% of these people will likely be admitted to hospital roughly 1 week longer than those who didn’t have COVID-19.
They will use 6.6% of pre-pandemic hospital bed-days at a time when almost 20% of hospitals have already averaged more than 100% annual occupancy rates.
Read 6 tweets

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