British hospitals were flooded with COVID-19 patients.Credit: Kirsty Wigglesworth / AFP via Getty
The news is sobering, but complicated. Scientists released the information last week following a warning from the UK government that the rapidly spreading SARS-CoV-2 variant B.1.1.7 increases the risk of dying from COVID-19 compared to previous variants. But some scientists warn that the latest study – like the government’s warning – is preliminary and still does not indicate whether the variant is more deadly or just spreads faster, thus reaching greater numbers of vulnerable people.
The latest findings are worrying, but to draw conclusions, ‘more work needs to be done’, says Muge Cevik, a public health researcher at St Andrews University based in Edinburgh, UK.
Last week, British Prime Minister Boris Johnson said preliminary data from several research groups suggested that B.1.1.7, first identified in the UK, spreads faster than previous variants and is also associated with a higher risk of death. . On 3 February, researchers from the London School of Hygiene & Tropical Medicine (LSHTM) released an analysis1 of some of these data, indicating that the risk of dying is about 35% higher for people confirmed to be infected with the new variant.
In real terms, this means that for men aged 70-84, the number likely to die from COVID-19 increases from about 5% for those who are positive for the older variant, to more than 6% for those confirmed with B.1.1.7, according to the analysis. For men 85 years and older, the risk of dying increases from about 17% to almost 22% for those confirmed with the new variant. The analysis was not judged by peer.
Other groups are also studying whether B.1.1.7 and other new SARS-CoV-2 variants are more lethal than earlier versions of the virus.
Dominant variant
Since B.1.1.7 was first identified in the South of England in September, it has become the dominant variant in the UK and has spread to more than 30 countries. Nicholas Davies, an epidemiologist at LSHTM, and colleagues analyzed data from more than 850,000 people who were tested for SARS-CoV-2 between November 1 and January 11, but who were not in the hospital.
Despite the fact that the B.1.1.7 variant was new, the researchers were able to identify people who were infected with it due to an error in a standard diagnostic kit used in the United Kingdom. The test normally looks at three SARS-CoV-2 genes to confirm the presence of the virus. But in the case of B.1.1.7, changes to the vein protein mean that people who are infected still test positive, but only for two of these genes.
The team found that B.1.1.7 is more lethal than previous variants for all age groups, genders and ethnicities. “This provides strong evidence that there is indeed an increased mortality rate of the new strain,” said Henrik Salje, an epidemiologist at Infectious Diseases at the University of Cambridge, UK.
Although Cevik says that the small number of deaths among young people included in the analysis is not enough to conclude that the new variant affects all ages equally. “It seems to really affect older age groups,” she says.
This is to be expected as the chance of dying from COVID-19 increases significantly with age, says Tony Blakely, an epidemiologist at the University of Melbourne, Australia.
The findings are also consistent with other preliminary work summarized in a document published on January 22 by the New and Emerging Respiratory Virus Threats Advisory Group (known as NERVTAG), a government advisory group. One research team from Imperial College London found that the average mortality rate – the percentage of people with a confirmed COVID-19 who would die as a result – was about 36% higher for people infected with B.1.1.7.
Other explanations
Cevik says more data and analysis are needed to determine if the variant is more lethal than other sexes. The latest study, for example, does not look at whether people infected with the variant have underlying comorbidities, such as diabetes and obesity, and are therefore more vulnerable and are at greater risk of dying, she says.
The study also covers only a small fraction of COVID-19 deaths in the UK – around 7% – and the effect could disappear if deaths in people tested in hospitals are included, Cevik said. Preliminary work by other groups has not found an increased risk of death in people admitted to hospitals with the new variant, and this complicates the latest results.
Davies says it is possible that the new variant could cause more serious illnesses, which means that more people end up in hospital, but that once the risk of dying can be the same as before. But he agrees that more information is needed before researchers can understand what’s going on.
Some researchers have also suggested that B.1.1.7 may contribute to an increase in deaths due to its rapid spread, which will overwhelm hospitals and affect the quality of care. But Davies says he and his team ruled it out because they were comparing the death risks associated with the new and older variants to people who were tested at the same time and at the same time, and would therefore be subject to the same conditions in hospitals. be.