COVID-19: Top science stories of the week, from a life-saving drug to one billion at risk

First life-saving drug identified and it's cheap and widely available

A randomized, controlled clinical trial (the ‘gold-standard’ for establishing the effectiveness of medical interventions and treatments) has found that the steroid dexamethasone prevents one in eight deaths for severely ill coronavirus patients on ventilators. It was also found to prevent one in 25 deaths for coronavirus patients requiring oxygen and did not show any benefit for milder cases where patients did not require oxygen. This is the first life-saving drug that has been identified in the search for therapeutics to help manage COVID-19. In further good news, it is cheap and readily available with a full course costing, for example, less that £35 in the UK.

Dexamethasone helps severely ill patients by suppressing the body’s immune system. Under normal circumstances the body relies on the immune system to attack and overcome infection but sometimes it can go into over-drive and begin targeting the body’s own cells. This can occur in severe cases of COVID-19 and is thought to be as dangerous as the viral infection itself. By dampening down the immune system dexamethasone effectively re-directs it to attack only the virus, helping to save lives. This also explains why the drug showed no benefit in milder hospitalized cases where patients’ immune systems are still functioning normally. The study did not look at non-hospitalized cases.

In light of recent cases involving the retraction of scientific papers on COVID-19 it should be noted that the results of this study have not yet been peer-reviewed or published in a scientific journal and the researchers are working to publish the full details as soon as possible.

A new analysis from researchers at the London School of Hygiene and Tropical Medicine has confirmed that the more than 20% of the world’s population that has at least one underlying condition is at greater risk of becoming seriously ill with COVID-19. Looking at data from 188 countries, the team estimates that 1.7 billion people worldwide have an elevated risk of ‘severe’ illness when looking at prevalence of conditions such as diabetes and cardiovascular problems that predispose those infected with SARS-CoV-2 to severe COVID-19. Once a vaccine is developed, the results of the study could be used to prioritise access.

A study (PDF) in Geneva, Switzerland found that children and the elderly are significantly less likely to show evidence of past SARS-CoV-2 infection than adults. The effort, led by Dr Silvia Stringhini, tested 2700 people for antibodies produced by the immune system in response to SARS-CoV-2 infection. Less than one percent of children aged 5-9 and just over four per cent of adults aged over 65 participants tested positive for antibodies. This contrasts with nearly 10% of adults aged 20-49 being found to test positive.

The researchers say these results are consistent with “a small but growing body of evidence that suggesting that young children are both infected and develop severe disease less often than adults”. They ascribe the lower prevalence among elderly as evidence that physical distancing measures are succeeding but note it isn’t possible to discount that ageing immune systems may be develop a weaker response to the virus and therefore not be detected by the tests.

The immune response of a small group of asymptomatic individuals was the focus of a joint study led by researchers from Chongqing Medical University and Chongqing Center for Disease Control and Prevention. Their findings suggest that asymptomatic SARS-CoV-2 infections result in weaker immune responses than symptomatic infections both at the height of infection and throughout recovery. They also noted that, in contrast to antibody responses to previous coronaviruses, a high proportion of the individuals in their study showed decreasing levels of antibodies within two to three months after infection. Although the small sample size of the study makes it hard to draw any conclusion with a high degree confidence, should their findings be replicated in future, larger studies this may have implications for the viability of COVID-19 ‘immunity passports’, and help to inform long-term immunity strategies.