In a study published Monday, researchers found that there may be an increased risk of death associated with the coronavirus variant first detected in the United Kingdom, termed the B.1.1.7 variant. 

The study was co-written by UC Berkeley Public Health professor Nicholas Jewell and researchers from the London School of Hygiene and Tropical Medicine. 

While the U.K. variant was previously discovered to have an increased risk of transmission and hospitalization, new analyses show an increased mortality rate of approximately 55% compared to previous variants, according to study co-authors John Edmunds and Ruth Keogh. 

“It is important to consider how this 55% relative increase in mortality translates into absolute risks,” Keogh said in an email. “Out of 1,000 people in their 60s who test positive for the old variant, six of them might be expected to die from COVID-19 in the four weeks following the test, but this rises to about nine with the B.1.1.7 variant, according to our estimates.”

The variant was first detected in the English county of Kent in Sep. 2020, according to Keogh. However, by early 2021, it became the more prevalent variant in the U.K., comprising 95% of COVID-19 infections in England by mid-February. 

The study used data from 2,245,263 positive SARS-CoV-2, the virus that causes COVID-19, cases and 17, 452 COVID-19 deaths in England from the beginning of September to mid-February, according to Keogh. The statistical technique of Cox regression was used to estimate the impact of the new variant on mortality rates. 

Keogh added that the researchers did not seek to answer why the variant has an increased mortality rate, but Keogh speculated that it could be associated with a higher viral load.

“The general speculation … is that the B.1.1.7 variant is more present in the upper respiratory tract of people infected with that variant, and that means they produce a greater viral load,” Jewell said. “People may be expelling more virus when they are sick with the B.1.1.7 variant when they are coughing or speaking or sneezing.” 

In regards to increased risk of morality, Jewell noted that the increased viral load may be a reflection of growth in virus replication which can put organs at a higher risk of complications that lead to death.

Along with the 55% increased risk of mortality, the risk of hospitalization appears to be about 50% higher, and the risk of transmission appears to be about 50 to 70% higher, according to Edmunds. 

“The fact that it has a worse outcome means that we have to work harder to stop people catching this particular variant,” Jewell said. “It means we need to maintain normal public health practices of social distancing and wearing masks to try and keep transmission at a minimum, and have people vaccinated as rapidly as possible.”