A study published in the journal Nature suggest the U.K. strain may cause a 61% higher risk of 28-day mortality.
Although the new and emerging strains of COVID-19, specifically the South African, U.K. and Brazilian strains, all appear to be more infectious than the original Wuhan wildtype virus, the South African and Brazilian strains do not appear to be more deadly. However, data is starting to accumulate to support the theory that the U.K. strain, B117, is more lethal.
A study published in the journal Nature suggest the U.K. strain may cause a 61% higher risk of 28-day mortality. Which is to say, the risk of dying from the U.K. strain at the 28-day mark is 61% more likely than if infected with other strains. This supports findings published last week in BMJ that found B117 had a 64% higher 28-day risk of death in people 30 years or older.
It’s important to note that both studies also observed that the 28-day mortality risk was low for most populations.
“Crucially, our study is limited to individuals tested in the community,” the authors of the study wrote. “However, this restricted focus allows us to capture the combined effect of an altered risk of hospitalization given a positive test and an altered risk of death given hospitalized, while only the latter would be measurable in a study of hospitalized patients only.”
The study analyzed 2,245,263 positive COVID-19 community tests from the seven National Health Services regions in England from September 1, 2020, to February 14, 2021. Of them, 17,4512 (0.8%) were fatal. They used what is called Cox proportional hazard models to project the increased 28-day risk of mortality.
Only slightly over half of the tests had conclusive tests identifying the B117 mutation, so they were forced to estimate the B117 numbers, and they also used inverse probability weighting (IPW) to compensate for the missing data.
About 4,950 deaths had known S gene target failure (SGTF, B117 mutation), which was 8.3% of the cohort’s deaths and 9% of England’s total COVID-19 deaths over the period evaluated. They adjusted for things like demographics and testing data and calculated the increased risk of 28-day mortality from the B117 variant compared to other strains, which was 55% in the verified group and 61% for the whole cohort.
They further calculated that this meant a 28-day mortality rate of 0.9% for 55- to 69-year-old males. The data becomes more complex when breaking down by other gender or age-group combinations, although the gist was that risk grew as age increased, which is consistent with what is known about COVID-19 in general.
For example, women and men 70 to 84 years of age had increased B117 mortality rates of 4.4% and 7.2%, respectively. People 85 and above had an even greater risk of death from B117 compared to other strains, increasing 6 to 8 percentage points, for a mortality figure of 19% and 25%.
“Our analysis suggests that B.1.1.7 is not only more transmissible than preexisting SRS-CoV-2 variants, but may also cause more severe illness,” the authors wrote. They did not, however, evaluate the possible mechanisms of the B117 variant, which could change the interpretation of the data.
Generally, the existing vaccines appear to be effective against the variants, although significantly less so for the South African variant. Vaccine experts and public health officials, as well as the vaccine manufacturers, point out that the vaccines can—and are—being tweaked to better treat the variants, should it be necessary.
Meanwhile, the recommendations to the variants for the public are exactly the same as for the original wildtype—wear masks in public, socially distance, wash your hands regularly and thoroughly, and get a vaccine as soon as possible.
