United Kingdom Prime Minister Boris Johnson announced last week that people infected with the first reported coronavirus virus in the country may be at greater risk of death than those receiving the original virus.
“There is some evidence that the new variant may be associated with higher mortality,” he said at a press conference on Friday.
Studies have shown that the variant, known as B.1.1.7, is more infectious than its viral predecessors. But evidence suggested that the strain was not fatal so far.
Britain’s Chief Scientific Advisor Patrick Valence said on Friday, “On average 10 out of 1,000 of the old version died in the UK, while 13 out of 1,000 have increased.” However, he insisted that the evidence remained “inconclusive”.
Some experts have said that just because more people are dying from this version does not mean that it is more deadly than other versions. It may be that the UK’s health system has dominated the country’s coronavirus case spike, or that the increased infectiousness of stress enables it to infect more people with underlying health conditions.
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Johnson’s announcement was based on research gathered by the UK’s New and Emerging Respiratory Virus Threatus Advisory Group (NERVTAG), which analyzed differences in mortality between those in the UK that b.1.1.7 and other strains Were infected with.
After controlling for variables such as a patient’s age, gender and geographical location, researchers at the London School of Hygiene and Tropical Medicine and Imperial College London found that, on average, people infected with B.1.1.7 had a 30% higher mortality rate. rate.
A follow-up analysis from Public Health England analyzed data collected between 23 November and 4 January, and found that B.1.1.7 was 65% fatal compared to other strains. Meanwhile, researchers at the University of Exeter looked at samples collected from 1 October and found that those infected with the variant were nearly twice as likely to die.
However, the researchers found no evidence that people infected with B.1.1.7 were hospitalized at higher rates.
“If the severity of infection has increased,” NERVTAG wrote, “we would expect an increased risk of hospitalization.”
However, William Scheffner, an infectious disease specialist at Vanderbilt University, told Insider that it is possible that very few people were going to hospitals for treatment, particularly given reports that UK hospitals were overshadowed.
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The World Health Organization said on Friday that it still needed to see if the data was used before confirming whether UK official B1.1.7 version actually causes more serious illness.
If the strain is indeed more lethal, one possible reason may be that those infected with B.1.1.7 have a higher viral load, meaning that they produce more viral particles when infected. Higher viral loads, many studies show, are associated with greater risk of death and more severe disease.
“That was the first thing that definitely came to my mind,” Scheffner said. “It would make great sense.”
This may also explain the increased infectivity, as particles that are viral by one person are more likely to infect others.
But it is also possible that the increased communicability of the variant is indirectly causing high mortality, whereas the stress itself is not fatal. B.1.1.7. It has several mutations to code for its spike protein, which the virus uses to invade cells, making it 50–70% more infectious than the original.
One such possibility is that because there are too many cases in the UK, healthcare systems are stressed and resources are scarce. This on its own can lead to high mortality.
“If your cases go out of control, your deaths will go out of control,” said Mike Ryan, executive director of the WHO’s Health Emergencies Program, at a press conference on Friday.
It is also possible that the increased permeability of strains infects the virus to more people who are at higher risk of serious illness.
“This can’t happen because the virus itself is making anyone more likely to get severe COVID,” Scheffner said. “It can occur for people more susceptible to the infectious virus who have underlying health problems such as diabetes or lung disease.”
A more contagious strain can result in a higher death toll than a more fatal one
The findings of UK researchers were based on only 8% of the total deaths in the UK during the study period, which is why Wallance still considers the evidence to be “not strong yet”.
“Results from all studies may therefore not be representative of the total population,” NERVTAG concluded.
Scientists must genetically sequence a patient’s blood or saliva sample to determine which strain is infected and kill a person. The process is time-consuming, and samples collected from patients are not always sent for sequencing.
Data also did not account for any underlying health conditions in people who died from COVID-19, which may have reduced mortality.
However, regardless of the quality of the data, and regardless of whether the new strain is in fact more lethal, its prevalence will certainly lead to a higher death overall, as infected individuals will spread it to more people.
Adam Kucharski, an epidemiologist at the London School of Hygiene and Tropical Medicine, Compared to three fictional scenarios on Twitter To demonstrate this.
Suppose the core strain of coronavirus has a reproductive value (mean average number of people who are ill) which is 1.1 and kills 0.8 out of every 100 people who become ill. In a population of 10,000 people, the virus will kill 129 people in a month.
But then say two new strains emerged, one of which is 50% fatal, while the other is 50% more infectious. 50% more lethal stress will kill 193 out of 10,000 people a month. But this strain would be 50% more communicable causing 978 out of 10,000 deaths due to its rapid spread at that time.
Ana Medaris-Miller contributed to reporting this story.