The 28-day risk of death for the B117 COVID-19 variant was 64% higher than for strains that previously circulated in people over 30, a UK study concluded.
The study, led by researchers at the University of Exeter and published today in BMJ, involved community-based tests and death data from 54,906 matching pairs of participants who tested positive for COVID-19 from October 1, 2020 to January 29, 2021.
Of the total 109,812 participants, 367 (0.3%) died. Of the 54,906 participants infected with B117, 227 (0.4%) died, compared with 141 (0.3%) infected with other strains.
The risk ratio (HR) for death at 28 days after diagnosis was 1.64 (95% confidence interval [CI], 1.32 to 2.04) for patients infected with variant B117, compared to previously circulating SARS-CoV-2 strains.
Although the HR for death was not significantly higher in those infected with B117 up to 14 days after diagnosis, it increased to 2.40 (95% CI, 1.66 to 3.47) during days 15 to 28. Participants who died were older (average age, 66.9 vs 46.3 years) than their peers, and more were men.
“In this comparatively low-risk group, this represents an increase in deaths from 2.5 to 4.1 per 1,000 cases,” wrote the authors. “The risk ratio increased between 1.32 and 2.04, higher than for other variants, translates into an increase of 32% to 104% in the risk of death, with the estimate of the most likely risk ratio of 1 , 64, or an increased risk of death of 64%. The absolute risk of death in this group of participants identified by the community, however, remains relatively low. “
B117 was first identified in the UK in October 2020 and quickly became dominant, triggering a national blockade and raising concerns about the possible increase in transmission and severity of the disease.
The absolute risk remains low
Those diagnosed with B117 infection had higher viral loads at the time of diagnosis than those infected with other variants, which, according to the authors, could be attributed to a variant characteristic or the tendency of these participants to seek care when they were most contagious. .
The researchers warned that their results may not apply to other settings and age groups, because their study included only about 8% of COVID-19 deaths in England during the study period. Only 26% of COVID deaths occurred in the community during that period, and data on the status of B117 was available for only 30% of those deaths. “Whether the increase in mortality from community-based tests is also seen in elderly patients or inpatients in hospitals, is not yet known,” they said.
Leon Danon, MSci, MSc, PhD, senior author of the University of Bristol study, said in a University of Exeter press release: “We concentrated our analysis on cases that occurred between November 2020 and January 2021, when the old variants and A new variant was present in the UK. This means that we were able to maximize the number of ‘matches’ and reduce the impact of other biases. Subsequent analyzes confirmed our results. “
B117 is believed to be highly transmissible due to mutations in parts of the virus genome that encode the spike protein responsible for binding to human cells, but the effects of these mutations on disease severity, outcomes and mortality rates remain unclear. Future research, the authors said, may help to better inform the allocation of resources and distribution of vaccines and identify ideal times to alleviate public health restrictions.
“Health capacity planning and national and international control policies are all impacted by this discovery, with increased mortality giving weight to the argument that more coordinated and rigorous measures are justified to reduce deaths from SARS-CoV-2 “, concluded the researchers.
Danon added in the press release, “SARS-CoV-2 appears capable of mutating quickly, and there is a real concern that other variants will emerge with resistance to rapidly launched vaccines. Monitoring for new variants as they arise, measuring their characteristics and acting appropriately should be a key part of the public health response in the future. “