CORONA: WHAT THE SCIENTISTS NOW KNOW

Keeping 2m apart may not be enough Virus stays on plastic for 72 hours 20-somethings can be ‘silent spreaders’

Three months ago, most of us had never heard of the Covid-19 coronavirus, far less imagined how it would change our lives.

Now, there are more than a million people infected worldwide and it is claiming the lives of hundreds of Britons a day. And we still have no idea when the outbreak will end and life will get back to normal.

At the same time, our scientific understanding of the virus is advancing at a remarkable pace. So, what have we learnt about coronavirus, and how might that knowledge help us defeat it?

In a new TV programme airing this Thursday on BBC2, leading doctors explore the latest information on the virus, how it is spread and when we might have a vaccine to protect us from it. here, they talk through the findings exclusively with Good health.

WHY THE TWO-METRE RULE MAY NOT BE ENOUGH

SoCIAl distancing guidance is to keep two metres away from people we don’t live with. This rule is thought to be based on experiments from the 1930s that suggested droplets released from coughs and sneezes can travel between one and two metres.

But this understanding may be outdated. In an experiment to be shown this week, led by the health and Safety executive, a cough from a medical manikin called Violet provides a graphic illustration of just how easily and how far coronavirus particles can spread.

In the demonstration, Violet coughs up a liquid laced with a dye that shows up under ultraviolet light. The dye is meant to reveal how droplets containing coronavirus particles are propelled through the air when we cough.

‘You see thousands of droplets coming out of Violet’s mouth, with some reaching the ceiling and the far wall, which is at least two metres away,’ says Dr Guddi Singh, a paediatrician in london who expects to be redeployed to the adult intensive care unit at any moment.

‘Some of these droplets land on my hand, even though I am not in the direct line of the cough. If these droplets contained the virus, I would be infected. It is incredibly contagious.

‘The experiment shows me why we need social distancing of at least two metres,’ she says. ‘But even at that, you are just on the fringe of where the spread could be happening.’

Indeed, new research published in the Journal of the American Medical Association suggests that two metres may not be nearly far enough; that coronavirus particles can be propelled up to eight metres by sneezes and six metres by coughs.

Some experts suggest that the larger droplets in saliva and mucus — the ones believed to carry Covid-19 — will fall safely to the ground within two metres. however, the U.S. researchers said their experiment calls into question our understanding of what a safe distance might be to protect ourselves from coronavirus infection.

Another report even suggests we may have more than coughs and sneezes to worry about. The prestigious National Academy of Sciences in the U.S. recently warned that the virus may also be spread by the fine mist we produce when we talk and breathe. one study suggests this can spread genetic material from the coronavirus more than two metres away from patients. This raises the possibility that the virus can linger in the air and potentially infect someone who walks by later.

All this research has prompted the World health organisation (Who) to start a review of its advice on the use of face masks.

WILL A FACE MASK HELP OR NOT?

There has been much debate over the value of face masks to both protect you from coronavirus and also to stop you spreading it.

Many scientists are sceptical about whether it is worth healthy people wearing masks. There are concerns about people’s hands becoming contaminated when they put on and take off the masks, and that someone wearing a mask might lower their guard in other ways — for example, by cutting back on their handwashing.

Plus, the virus can still get in through any gaps at the sides of the masks and the person’s eyes (a possible entry point for the virus) are still exposed.

Chris van Tulleken, an infectious diseases doctor at University College london hospitals NhS Foundation Trust, isn’t convinced that healthy people need to wear masks. he says having something on your face may make you want to touch it more — and ‘if you keep two metres away from everyone else outside, you don’t need a face mask’. however, others argue that masks can provide a physical barrier to the droplets that spread the virus, particularly from people who are infected and don’t have any symptoms.

The World health organisation is currently reviewing its advice that face masks should only be worn by those who have coronavirus or by those people looking after others who may have it.

DILEMMA OF THE ‘SILENT SPREADERS’

The spread of Covid-19 by people who aren’t showing symptoms is one of the reasons the virus is so dangerous. A study published in the journal Science concluded that 86 per cent of cases have either no symptoms or only very mild ones.

Countries such as Iceland and

South Korea have reported a huge number of ‘silent spreaders’. In South Korea, 40.2 per cent of those aged 20 to 29 fell into this bracket.

It is not known why some people don’t show symptoms, but it may be due to differences in their genetics.

HOW LONG DOES THE VIRUS SURVIVE?

WheTher you have symptoms or

not, the virus will be released from your respiratory system into the air and the droplets can ‘last for many hours on different surfaces which we may then touch’, says Dr Singh.

‘A recent study in the New England Journal of Medicine revealed the virus can survive suspended in the air for up to three hours. It can stay on cardboard for 24 hours and plastic for 72 hours.’

This, says Dr Singh, could have implications for online shopping.

‘In countries that seem to have managed the outbreak pretty well, such as Singapore and Taiwan, all deliveries are treated very seriously because it is clear that this could be another mode of transmission.

‘With deliveries, there is advice that plastic items should be wiped down with soap and water.’

Other experts say you are unlikely to reach every nook and cranny, so would be better off keeping your hands clean.

IT’S NOT JUST A COUGH AND FEVER

ThE official advice is that the two main symptoms of Covid-19 are a high temperature and a ‘ new and continuous cough’. Indeed, data gathered by the WhO in February on more than 55,000 confirmed cases in China showed a fever to be the most common symptom, occurring in 87.9 per cent of cases, followed by a dry cough (in 67.7 per cent).

Other symptoms listed included fatigue, coughing up phlegm, sore throats, headaches and diarrhoea and vomiting.

In the last ten days of the pandemic, a new symptom has emerged: loss of sense of smell. Data collated by ENT UK, which represents ear, nose and throat specialists, suggests this inability to smell — and, often, to taste — may be the very first sign.

Indeed, a new report from King’s College London points to it being one of the most common symptoms. They analysed data submitted by 1.5 million users of a new symptom-tracking app. Those who had tested positive for the virus were much more likely to have lost their sense of smell and taste than have a fever. Dr van Tulleken, whose brother Xand has had Covid-19 for the past two weeks, says Xand’s sense of taste and smell was so affected by the virus that he was able to eat a pot of mustard. ‘It looks like this is quite a strong diagnostic predictor,’ says Chris. Xand, a normally healthy 41-yearold, ‘ had a high fever, extreme fatigue, muscle aches, dry cough and entirely lost his senses of smell and taste, says his brother Dr Chris. Xand also developed an abnormal heart rhythm and had to go into hospital for a cardioversion — a treatment that uses electric shocks to jolt the heart back into its normal rhythm.

YOUNGER PEOPLE ARE AT RISK TOO

IT IS known that older people and those with underlying conditions such as type 2 diabetes and heart and lung diseases, such as chronic obstructive pulmonary disease (COPD), are more likely to become severely ill with coronavirus. A report in The Lancet last week where researchers from Imperial College London analysed data from China showed how the risks of serious illness and death rise sharply as we get older.

This is thought to be because our immune systems weaken with age, making us more vulnerable to infections. Also, we are more likely to have underlying health conditions as we age that increase the risk of severe disease.

Also, a phenomenon called a cytokine storm — a potentially fatal overreaction of the immune system — becomes more common as we get older.

While a 20-year- old has about a 1 per cent chance of their illness being so severe that they are hospitalised, the risk rises to around 4 per cent for someone in their 40s; 8 per cent for someone in their 50s; and 19 per cent for the over-80s.

Yet, younger people are not invincible. Data from NhS England shows that while the vast majority of the 4,897 deaths in England have been in the over-60s, 396 ‘younger people’ under 60 have lost their lives to Covid-19.

‘This is something that even young people need to take carefully,’ says Dr van Tulleken.

So why can a seemingly young and healthy person be struck down with the virus? It is possible some people’s genetics makes them more vulnerable. Another theory revolves around the viral load — the amount of virus someone is initially exposed to.

With some viruses, the more you breathe in, the sicker you get, which could explain why young nurses who are in close contact

with lots of sick patients are dying from coronavirus.

TAKE FIGURES WITH A PINCH OF SALT

We’re surrounded by numbers, but just what should we believe? Very little, says mathematician Dr Hannah Fry , who presents the BBC2 show with Dr van Tulleken. Comparisons between corona-virus deaths in different countries, for example, can be misleading.

‘each country is counting things differently,’ says Dr Fry. ‘Some are choosing not to count the deaths that happened outside of hospitals, while others may not be counting cases where the individual was already sick.’

While the daily death rate in the UK is rising at an alarming rate, the figures don ’t tell us how fast the virus is actually spreading , explains Dr Fry, a lecturer in the mathematics of cities at Univer - sity College London.

‘The people who are dying today are likely to have contracted the virus up to three weeks ago,’ she says. Since then, a raft of restric - tions have been introduced and the effects of the lockdown have yet to be reflected in the figures.

Dr Fry expects the death rate in the UK to start declining soon.

‘In a way , things have already got better — we are just not going to see it until later,’ she says.

THE POWER OF HANDWASHING

In 2018, Dr Fry simulated a pandemic of a deadly flu virus. Her experiment revealed how quickly the contagion could be slowed simply by handwashing.

Washing hands an extra 5-10 times a day would halve the number of people who ‘caught ’ the virus in the next 100 days, slashing the number of patients from 42 million to 21 million.

‘The way that pandemics spread is all exponential, which means tiny things can have a massive impact. Things like handwashing, done properly , can genuinely make a difference,’ says Dr Fry.

Coronavirus, an Horizon special, BBC2, Thursday, 9pm.