Mortality And The U.K. Variant - The Headlines And The Data.

There is a new study out in the British Medical Journal that compares the mortality of folks who were infected either with the 'classic' versions of the SARS-CoV-2 virus or the U.K. variant.

Here is the lede from one of the less sensational news reports by Thomson Reuters posted by CBC News:

A highly infectious variant of the novel coronavirus that has spread around the world since it was first discovered in Britain late last year is between 30 per cent and 100 per cent more deadly than previous dominant variants, researchers said on Wednesday.

In a study that compared death rates among people in Britain infected with the new SARS-CoV-2 variant — known as B117 — against those infected with other variants of the COVID-19-causing virus, scientists said the new variant's mortality rate was "significantly higher."

The B117 variant was first detected in Britain in September 2020, and has since also been found in more than 100 other countries...

Here are the actual results and conclusions from the abstract of the paper itself:

Results: The mortality hazard ratio associated with infection with VOC-202012/1 (B.1.1.7/U.K. variant) compared with infection with previously circulating variants was 1.64 (95% confidence interval 1.32 to 2.04) in patients who tested positive for covid-19 in the community. In this comparatively low risk group, this represents an increase in deaths from 2.5 to 4.1 per 1000 detected cases.

Conclusions: The probability that the risk of mortality is increased by infection with VOC-202012/01 is high. If this finding is generalisable to other populations, infection with VOC-202012/1 has the potential to cause substantial additional mortality compared with previously circulating variants. Healthcare capacity planning and national and international control policies are all impacted by this finding, with increased mortality lending weight to the argument that further coordinated and stringent measures are justified to reduce deaths from SARS-CoV-2.

****

So.

In addition to the already established increase in infectivity the UK variant increases the risk of dying, at least within the study groups compaared here. 

This study was done in the community not hospitals (where infected folks tend to be sicker and older). Thus,  the overall mortality rate is quite low. Specifically, it goes from 0.25% in the case of the classic virus infection and 0.41% in the case of the variant infection. Regardless the low overall rates, the mortality rate increase in the case of variant infections is statistically significant.

The British research group that carried out the study did their best to rule out confounding variables by 'matching' subjects according to things like age, sex, ethnicity, date of sampling and health authority region. In other words, they did their best to make sure they were looking primarily at  changes that were due to the different strains of the virus and not other factors. 

However, there were at least two factors that they realized they had not ruled out entirely.

One factor was the level of viral infectivity of the two groups. In fact, those infected by the variant did appear to have higher viral loads. However, the researchers concluded that this increase in load didn't likely explain their overall findings.

Another factor was the possibility that those infected with the variant were actually farther along in the course of the disease when they got tested which would affect the mortality numbers given that they used a 28 days after the first positive test result as their study endpoint.

Regardless, the UK variant is now likely doubly concerning as its numbers rise in Canada. Despite this, an important thing to remember is that, as we've discussed before, the approved vaccines show good efficacy against this variant. And, obviously, continued strong public health measures and vaccines will be doubly, if not more so, protective against the variant.

______

On a somewhat related note, I don't know about you but I find the screaming local headlines about how some folks have tested positive in some longterm care facilities where the bulk of the residents have already been vaccinated deeply distressing given that  the initial clinical trials was designed to assess  outcomes not viral infectivity. Furthermore, as we've also discussed previously, while there are now some data that suggest that the vaccines likely decrease infectivity/transmission  it is not going to be 100%.  

.