Dr Zoë Hyde Profile picture
Oct 3, 2020 33 tweets 11 min read Read on X
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

Sep 23, 2023
Policymakers shouldn’t be trying to manage COVID-19 as if it were seasonal influenza. It’s not and never will be. SARS-CoV-2’s greater transmissibility leads to faster viral evolution. This means waves of disease throughout the year, rather than a single winter COVID season. 🧵
Thanks to vaccination, COVID-19 is far less deadly than it used to be. But a virus doesn’t have to put people in hospital to be disruptive. Leaving aside the issue of long COVID, frequent waves of infection will grind down economic productivity.
Many seem to believe COVID-19 will become seasonal, but why should it? Influenza generally isn’t very transmissible and infects a small number of people each year. There’s plenty of time to design vaccines based on what’s happening in the opposite hemisphere of the globe.
Read 6 tweets
Jul 23, 2023
(1/6) Respiratory viruses are much more likely to spread indoors than outdoors, but outdoor super-spreading events can still occur if the conditions are right.

A new study describes a SARS-CoV-2 outbreak affecting 131 people at a night market. 🧵 Picture of a night market.
(2/6) The outbreak happened when a family of 3 people infected with the omicron BA.5.2 variant visited a night market in Zhejiang Province, China, in July 2022. They spent 1 hour and 4 minutes at the market.
(3/6) On the evening of the outbreak, it was warm (27 degrees Centigrade), humid, and there was very little wind.

Most of the market stalls had big umbrellas and it was crowded. The market had a capacity of 5,000 people.
Read 6 tweets
Jul 22, 2023
Could future vaccines be administered via a patch? Researchers have developed skin patches containing tiny “microneedles” made of sugar and salt which dissolve on contact with skin, painlessly administering a vaccine in the process. 🧵
A key advantage of this technology is that a vaccine patch can induce a special kind of immunity in the skin, known as mucosal immunity, which can prevent infection and transmission. Injectable vaccines may only prevent severe disease.
Skin patch vaccines are also likely to have fewer side effects because of the way they slowly dissolve over minutes to hours.

This slow-release formula is less likely to trigger flu-like symptoms that sometimes follow injectable vaccines.
Read 4 tweets
Jul 10, 2023
Imagine if you could rapidly detect COVID-19 in public places by testing the air. Now you can! Researchers have developed a groundbreaking new air monitor that can detect the presence of an infected person in as little as 5 minutes. 🧵
The compact device, which measures 12 x 10 x 10 inches, has a sensitivity of ~80% and can detect as few as 7 viral RNA copies per cubic metre of air with a resolution of 5 minutes.
The major limitation of the prototype is noise (75-80 dB; similar to heavy traffic), although the researchers are trying to develop a quieter version with low-noise motors and/or sound-proofing.
Read 5 tweets
Jan 1, 2023
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, 2023
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

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