Thread by @DrZoeHyde

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).

https://twitter.com/DrZoeHyde/status/1286985284102443008?s=20

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.

https://twitter.com/DrZoeHyde/status/1312041160920100865?s=20

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.

https://twitter.com/DrZoeHyde/status/1304381594820517888?s=20

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.

https://twitter.com/DrZoeHyde/status/1297165794476843010?s=20

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.

https://twitter.com/DrZoeHyde/status/1311687988032667649?s=20

8. This supports previous work from Italy, showing that the contacts of children were more likely to be infected than the contacts of adults.

https://twitter.com/DrZoeHyde/status/1288779767131459587?s=20

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.

https://twitter.com/DrZoeHyde/status/1304703213950480384

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.

https://twitter.com/DrZoeHyde/status/1289182966623608837?s=20

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).

https://twitter.com/DrZoeHyde/status/1294245207089717249?s=20

13. In this study of mostly adults, asymptomatic and symptomatic cases were also found to have a similar viral load.

https://twitter.com/DrZoeHyde/status/1291730820609105920?s=20

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%).

https://twitter.com/DrZoeHyde/status/1301554715595911168?s=20

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.

https://twitter.com/DrZoeHyde/status/1300023245127610369?s=20

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.

https://twitter.com/DrZoeHyde/status/1296334190955261952?s=20

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.

https://twitter.com/DrZoeHyde/status/1306635443262218240?s=20

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.

https://twitter.com/DrZoeHyde/status/1305032602810609664?s=20

24. In the UK, the number of #COVID19 clusters in educational settings has surged since schools reopened.

https://twitter.com/DrZoeHyde/status/1309855267660554241?s=20

25. Similarly, in France, clusters in schools and universities account for one-third of those currently under investigation.

https://twitter.com/DrZoeHyde/status/1310221012567379968?s=20

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.

https://twitter.com/DrZoeHyde/status/1302982131375693824?s=20

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.

https://twitter.com/DrZoeHyde/status/1305850139412541442?s=20

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.
theconversation.com/children-might…

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.

https://twitter.com/DrZoeHyde/status/1309867910286905346?s=20

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.

https://twitter.com/DrZoeHyde/status/1287774646847156232