A review of research on the COVID variant B.1.1.7, also known as ‘the UK variant’, has shown it to be 30% to 70% more deadly than the original wild-type COVID strain.
Concerns over the deadliness of B.1.1.7 were raised in January, when the UK government’s New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) presented initial findings suggesting that B.1.1.7 cases were deadlier than non-variant cases. After this, they released an updated report which is available online. The report makes the cases that the earlier linked community testing and mortality data were all based on the same datasets, and so had the same biases. However, the group explained that the new analysis was more valid.
“More recent analyses have added a wider range of data sets and been able to control for additional confounders, increasing confidence in the association of the [variant of concern] with increased disease severity,” the group wrote.
London School of Hygiene & Tropical Medicine found a relative hazard of mortality within 28 days was 1.58 for variant-infected individuals, while Imperial College London used a case-control weighting method to find a case fatality ratio of 1.36 for variant cases. Public Health England found a “death risk ratio” of 1.65 in matched cohort analysis for variant cases versus non-variant cases.
A number of other studies investigated the variant’s impact on hospitalisation. Public Health Scotland used S-gene target failure as a proxy for variant case detection. They found that S-gene target failure cases had a higher risk for hospitalisation than the S-gene positive cases.
Some studies did not support the higher fatality risk, such as the UK’s Office for National Statistics (ONS), which said that “the number of deaths are too low for reliable inference.”
A number of limitations were reported in the study, including potential bias in case ascertainment, representativeness, unmeasured confounders and secular trends. They also tried to control for nursing home status in hospital reports, but not all of these could be excluded.
“There are potential limitations in all datasets used but together these analyses indicate that it is likely that … B.1.1.7 is associated with an increased risk of [hospitalisation] and death compared to infection with non-[B.1.1.7] viruses,” the group concluded.
In mid-January, modelling by the CDC indicated that the UK variant would become the dominant strain in the United States by March. At the end of January, President Joe Biden had pledged to increase vaccinations to 1.5 million per day, a target which would still not be able to contain the spread of the variant.
Source: MedPage Today
