UK hospitals are inundated with COVID-19 patients.Credit: Kirsty Wigglesworth / AFP via Getty
The news is sobering, but complicated. Scientists released the data behind a UK government warning last week that the rapidly spreading SARS-CoV-2 variant B.1.1.7 increases the risk of death 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 is simply spreading faster and thus reaching a greater number of vulnerable people.
The latest findings are alarming, but “more needs to be done” in order to draw conclusions, said Muge Cevik, a public health researcher at the University of St Andrews, based in Edinburgh, UK.
Last week, UK Prime Minister Boris Johnson said preliminary data from several research groups suggested that B.1.1.7, which was first identified in the UK, spread faster than previous variants and was also associated with a higher risk of death. On February 3, researchers from the London School of Hygiene & Tropical Medicine (LSHTM) released an analysis1 of some of that data, suggesting that the risk of death 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 rate likely to die from COVID-19 increases from about 5% for those who test positive for the older variant, to more than 6% for those confirmed with B .1.1.7, according to the analysis. For men 85 or older, the risk of death increases from about 17% to almost 22% for those infected with the new variant. The analysis has not been peer-reviewed.
Other groups are also investigating whether B.1.1.7 and other new SARS-CoV-2 variants are more deadly than previous versions of the virus.
Dominant variant
Since B.1.1.7 was first identified in Southern England in September, it has become the dominant variety in the UK and has spread to more than 30 countries. To investigate whether the lineage causes an increased risk of death, 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 were hospitalized. .
Despite the fact that the B.1.1.7 variant was new, the researchers were able to identify people infected with it due to a malfunction in a standard diagnostic kit used in the UK. The test normally looks for three SARS-CoV-2 genes to confirm the presence of the virus. But in the case of B.1.1.7, changes to the spike protein mean that people who are infected will still test positive, but for only two of these genes.
The team found that B.1.1.7 is more deadly than previous variants for all age groups, genders, and ethnicities. “This provides strong evidence that there is indeed increased mortality from the new strain,” said Henrik Salje, an infectious disease epidemiologist at the University of Cambridge, UK.
Although Cevik says that the small number of deaths among young people included in the analysis is not sufficient to conclude that the new variant affects all ages equally. “It really does seem to 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 preparatory work summarized in a paper published Jan. 22 by the New and Emerging Respiratory Virus Threats Advisory Group (known as NERVTAG), a government advisory group. A research team from Imperial College London found that the average death rate – the percentage of people with confirmed COVID-19 who will die as a result – was about 36% higher for people infected with B.1.1.7.
Other explanations
Cevik says more data and analysis is needed to conclude whether the variant is more deadly than other lines. For example, the latest study doesn’t look at whether people infected with the variant have underlying co-morbidities, such as diabetes and obesity, and are therefore more vulnerable and at higher risk of dying, she says.
The study also covers only a small fraction of COVID-19 deaths in the UK – about 7% – and the effect could disappear if deaths in people tested in hospitals are included, Cevik says. Preparatory work by other groups has not shown an increased risk of death in people admitted to hospitals with the new variant, and this complicates the latest results.
Davies says it’s possible the new variant could cause more serious illness, putting more people in the hospital, but that, once there, their risk of death could be the same as before. But he agrees that more data is needed before researchers can understand what’s going on.
Some researchers had also suggested that B.1.1.7 might contribute to an increase in deaths due to its rapid spread, overwhelming hospitals and compromising the quality of care. But Davies says he and his team ruled that out because they compared the risks of death to the new and older variants for people who were tested at the same time and place and thus would be subjected to the same conditions in hospitals.