Latest COVID-19 science updates: who’s most at risk, disease-predicting apps and asymptomatic transmission

Each week, Channel 4 News will provide a summary of key research papers, studies or developments from the world of COVID-19 science.

Study suggests 20% of the population should be shielded because of their coronavirus risk

A study published in The Lancet has suggested that 20% of the population should be shielded because of their high risk of dying from coronavirus – including some who aren’t currently being told to do so by the government.

The study by researchers at University College London, published on Tuesday, found that various underlying health conditions do not pose an even risk across the whole population and that therefore people’s risk of dying from the virus goes far beyond age alone.

Experts commenting on the findings said easing the lockdown too soon and not shielding those truly at high risk could be fatal for some.

The study authors set out to better understand how different types of coronavirus risk, including age, sex and underlying conditions, interact with each other.

They used statistical models, which incorporate these risk factors indicated by the government such as age and diabetes, to calculate likely excess mortality figures under different scenarios.

The models suggest that between 18,000 and 37,000 excess deaths may occur with moderate coronavirus suppression measures, and that in the worst case scenario there could be up to 73,000 excess deaths.

Experts commenting on the findings urged caution in looking at these excess mortality figures, and suggested that more useful conclusions should be drawn about who is really most at risk from coronavirus.

Sarah Harper, Clore Professor of Gerontology at University of Oxford pointed out, for example, how the paper identified that a man aged 66-70 with no underlying health conditions is not currently considered high risk by the government. But their risk is higher than a woman aged 56-60 with an underlying health condition, who is considered high risk by the government.

“Similarly, it shows that generally women’s mortality risk at any given age is the same as men’s who are around 5 years younger,” Professor Harper said.

Study looks at disease-predicting app based on symptoms alone and confirms loss of smell and taste are common in coronavirus cases

A study published in Nature Medicine has taken the first steps in developing an app-based algorithm to predict whether someone has coronavirus based on symptoms alone.

In the study, published on Monday, researchers invited 2.6 million people in the UK to use an app to record potential COVID-19 symptoms.

The idea behind what came next is simple. If enough participants systematically reported their symptoms at the same time as having a reliable test for the virus, then a statistical relationship could be determined between reported symptoms and virus presence. This could then be used to develop an algorithm to predict whether someone has the virus based on their reported symptoms alone.

The study went some way to showing this is possible, but only 0.7% of the 2.6 million app participants also had a test, so the resulting relationship outlined between symptoms and virus presence was limited.

The study did confirm, however, that loss of taste and smell is a symptom of people with the virus. This has been reported anecdotally before, but hadn’t been confirmed in a peer-reviewed study.

In the future, if similar studies could be carried out with a higher portion of participants being tested, experts said it may then be possible to create a reliable disease-predicting diagnostic tool based on symptoms alone.

Study finds three percent of hospital staff were coronavirus cases with no symptoms

A study of healthcare workers in a large hospital found that three percent carried coronavirus while displaying no symptoms.

The research, published on Monday, reported how 1032 asymptomatic healthcare workers were screened for the virus over a three week period, in addition to symptomatic staff and members of their household.

Three percent of these asymptomatic staff tested positive for the virus – though experts commenting on the findings said that the number tested was too small to accept as a figure for asymptomatic disease carriers more widely.

Ashley Woodcock, Professor of Respiratory Medicine at the University of Manchester and not an author on the study, said: “This work has major implications in addressing transmission in these settings. In hospitals this virus is contracted from patients by droplet spread with prevention by visors rather than facemasks. But healthcare workers could also be cross-infecting through contact with infected surfaces.”

Last week’s update can be found here.