The 28-day risk of death for the B117 COVID-19 variant was 64% higher than for previously circulating strains in people older than 30 years, a British study found.
The study, led by researchers from the University of Exeter, and published today in BMJ, involved community-based tests and deaths of 54,906 corresponding pairs of participants who tested positive for COVID-19 from October 1, 2020 to January 29, 2021.
Of the 109,812 total 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 28 days after diagnosis was 1.64 (95% confidence interval [CI]1.32 to 2.04) for patients infected with the B117 variant, compared to SARS-CoV-2 strains previously in circulation.
Although the HR for death up to 14 days after diagnosis was not significantly higher in those infected with B117, it increased during the days 15 to 28 to 2.40 (95% GI, 1.66 to 3.47). Participants who died were older (mean age 66.9 versus 46.3 years) than their peers, and more were men.
“In this relatively low risk group, it represents an increase in deaths from 2.5 to 4.1 per 1,000 cases,” the authors wrote. “The increased hazard ratio between 1.32 and 2.04, higher than for other variants, means an increased risk of death by 32% to 104%, with the most likely estimate of the hazard ratio being 1.64, or a 64 ‘increased risk of death. However, the risk of death in this group of community-identified participants remains relatively low.’
B117 was first identified in the UK in October 2020 and quickly became predominant, causing a national exclusion and raising concerns about possible increased transmission and severity of the disease.
The absolute risk remains low
Those diagnosed with B117 infections had a higher viral load at diagnosis than those infected with other variants, which the authors said could be attributed to a variant trait or to the tendency of these participants to seek care if they was most contagious.
The researchers warned that their results may not apply to other situations and age groups, as their study includes only about 8% of COVID-19 deaths in England during the study period. Only 26% of COVID deaths occurred in the community during that time, and only 30% of deaths were available on B117 status. “Whether the increase in mortality from community-based tests is also observed in elderly patients or in patients admitted to the hospital remains to be seen,” they said.
Leon Danon, MSc, MSc, PhD, senior study author from the University of Bristol, said in a news release from the University of Exeter: “We focused our analysis on cases that took place between November 2020 and January 2021. both the old variants and the there were a new variant in the UK. This meant we could maximize the number of ‘matches’ and reduce the impact of other biases. Subsequent analyzes confirmed our results.’
B117 is thought to be highly transmissible due to mutations in parts of the virus genome that encode the peak protein responsible for binding to human cells, but the effects of the mutations on the severity, outcomes and mortality rates of the disease remain unclear. Future research, the authors said, could help inform better resource allocation and vaccine distribution and identify optimal times to alleviate public health constraints.
“The planning of health care capacity and national and international control policies are influenced by this finding, with an increased mortality weight giving weight to the argument that further coordinated and rigorous measures are justified to reduce deaths due to SARS-CoV-2,” the researchers concluded.
Danon said in the news release: “SARS-CoV-2 appears to be rapidly able to mutate, and there is a real concern that other variants will emerge with resistance to rapidly unrolled vaccines. it arises, measures its characteristics and to act in the right way must be an important part of the public health response in the future. ‘