How does COVID-19 affect children - and what can we do to keep them safe?

That complexity is not helped by social media and by men with egos and views - men like electric car entrepreneur Elon Musk who tweeted: "Kids are essentially immune, but elderly with existing conditions are vulnerable."

Is he right?

Mr Musk has a point, but he is wrong.

Children are not immune, according to Professor Andrew Pollard who is acknowledged as one of the world's most authoritative experts on illness in children.

"At the beginning of the pandemic, it was thought that children are not getting infected with the coronavirus, but now it is clear that the amount of infection in children is the same as in adults," the Oxford University professor of paediatric infection told the BBC.

"It's just that when they do get the infection they get much milder symptoms."

Infants may be more likely to suffer than older children. A study in China concluded: "Although clinical manifestations of children's COVID-19 cases were generally less severe than those of [adult] patients, young children, particularly infants, were vulnerable to infection."

They are, but not in huge numbers.

A 12-year-old girl died in Belgium in March. A 14-year-old died in Portugal, a 16-year-old in France and a 13-year-old in Britain. It is, though, very rare.

Two of the big studies of coronavirus and COVID-19, the disease the virus causes, found no deaths among those in their teens and younger.

These studies - one in the United States and one in China - were done in the early stages of the pandemic, so information may have changed.

But the basic picture is that children who catch the disease are unlikely to die.

The US study of more than 4000 patients showed that the oldest were hit hardest.

"Overall, 31 per cent of cases, 45 per cent of hospitalizations, 53 per cent of intensive care unit admissions and 80 per cent of deaths associated with COVID-19 were among adults aged 65 and above, with the highest percentage of severe outcomes among persons aged 85 years and above," the study's summary says.

"In contrast, no ICU admissions or deaths were reported among persons aged 19 or younger.

"Similar to reports from other countries, this finding suggests that the risk for serious disease and death from COVID-19 is higher in older age groups."

Scientists are trying to work out if it can prompt a condition called Kawasaki disease, of which there are about 300 cases a year in Australia.

Some COVID-19 patients below the age of five have additional symptoms consistent with this second disease, including an inflamed heart.

This overlap has prompted scientists to speculate that COVID-19 may have triggered Kawasaki disease - but it needs further research.

It is true that children are at a lower risk of death or serious illness from the virus.

But they can infect others. They have parents and grandparents who might not survive the bug, particularly if those adults are very old, have heart conditions, are obese or have a string of other vulnerabilities.

Children get milder symptoms of flu but they can still infect others. The same is true of the coronavirus.

It seems that they are. They don't get the most severe symptoms, particularly the clogging of the lungs, leading to difficulty in breathing and then the failure of other organs - the symptoms which kill.

Scientists don't know why this is, but one theory is that children have more robust mechanisms in the body, which makes them less receptive to the virus or more able to fight it off.

We change as we grow - warts, asthma and eczema tend to disappear in adulthood, for example.

It may be that, in a similar but reverse way, proneness to coronavirus increases with age. Our systems for fighting off infections also weaken.

It is possible, but very rare. Reports from China in February said a baby was diagnosed as having the coronavirus barely a day after birth. The mother had tested positive just before birth, but it's still not certain where or how the baby contracted the virus.

Two Swedish researchers have crunched the numbers relating to 108 pregnant women who had COVID-19.

The two researchers, Mehreen Zaigham and Ola Andersson, concluded: "Our review did not find any evidence of mothers infecting their foetus with COVID-19."

They added that more research needed to be done, but they thought it "unlikely that a mother can infect her child while it is still in the womb. But this could change as more information becomes available."

"Most pregnant women infected with the novel coronavirus will experience it as a common cold, with fever and perhaps a sore throat or dry cough," the researchers said.

"Still, in our review, 3 per cent needed intensive care if infected during the last third of their pregnancy.

"It is vitally important that pregnant women follow the World Health Organization's advice: wash your hands frequently, maintain social distancing, avoid touching eyes, nose and mouth."

More research, certainly, as more information emerges. The more we learn, the more we realise we need to learn more.

And hard-headed consideration of opening schools. Keeping them closed may slow the spread of the germ, but closing them deprives children of education. It is a political judgment informed by science.

Have children wash their hands. And keep them away from elderly people.

Our COVID-19 news articles relating to public health and safety are free for anyone to access. However, we depend on subscription revenue to support our journalism. If you are able, please subscribe here. If you are already a subscriber, thank you for your support. If you're looking to stay up to date on COVID-19, you can also sign up for our twice-daily digest here.