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expert reaction to paper looking at mortality in patients infected with the SARS-CoV-2 variant of concern B.1.1.7

A paper published in the BMJ compares mortality of patients infected with the SARS-CoV-2 variant B.1.1.7, with those infected with previously circulating SARS-CoV-2 variants.


Dr Simon Clarke, Associate Professor in Cellular Microbiology at the University of Reading, said:

“This new, peer reviewed study has studied the lethality of the coronavirus that causes Covid-19 by directly comparing the outcomes of individuals infected in the community, either with the B.1.1.7 ‘Kent’ variant or other, pre-existing variants.  Other factors such as age, sex, ethnicity and socioeconomic status, could be eliminated by matching results to someone with a similar profile.

“Patients infected with the Kent variant were 64% more likely to die than those infected with other versions of the virus circulating in the UK. While it is important to note that absolute risk remained low, increasing from 2.5 to 4.1 deaths per 1000 cases, this is substantially higher than the 30-40% possible increase reported by Sir Patrick Vallance on 22nd January, which was dismissed as unlikely in some quarters. Unsurprisingly, the increase in lethality is largest in men and increases with age.  Further data is needed to make any meaningful conclusions on ethnicity or socioeconomic status. 

“It is now well established that the Kent variant is more transmissible; it has come to dominate in the UK and it is increasing in prevalence in other parts of the developed world.  This increased lethality, in addition to the increased transmissibility, means that this version of the virus presents a substantial challenge to healthcare systems and policy makers.  It also makes it even more important people get vaccinated when called.”


Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, University of Leicester, said:

“Again, I’m still not yet very convinced by these results. 

“Clinical teams know that the coldest winter temperatures occurring in Jan/Feb can exacerbate all the comorbidities that predispose to more severe outcomes of COVID-19 – like chronic heart, lung, renal, neurological diseases – including diabetes, hypertension (stressing the heart).

“So without the careful matching of comorbidities in the VOC and non-VOC arms, these differential clinical severity model outcomes are still questionable. 

“We really need to revisit this in Spring to account for the cold weather factor – and there are also other seasonal variables related to shorter daylight hours, such as melatonin levels that may impact differentially on VOC vs. non-VOC clinical outcomes – related to host immune responses. 

“Also, there is another possible confounder within the last few months which may impact on the VOC/non-VOC unequally, I.e. the winter timing of this 3rd lockdown – which adds to various stress factors due to lack of exercise, increased consumption of junk food, stresses related to home schooling, increased and prolonged economic stress, ongoing lack of attendance for other healthcare problems, etc. which may impact on various host immune responses to these viruses.

“But at the end of the day, we just deal with all such cases as and when they present to the NHS – so this type of analysis does not really impact on that.”


Prof Lawrence Young, Virologist and Professor of Molecular Oncology at the University of Warwick, said:

“This study confirms previous work showing that infection with the B.1.1.7 virus variant is associated with an increased risk of death. It is one of the studies that was presented by NERVTAG earlier this year which reported similar preliminary data from the London School of Hygiene and Tropical Medicine and from Imperial College.

“This independent study from Exeter University is a case-control analysis of community testing data linked to death data all adjusted for age, sex, ethnicity and location. It confirms that infection with the B.1.1.7 variant is associated with 64% higher risk of death (mortality hazard ratio) in those testing positive for COVID-19 in the community. The study is based on community (pillar 2) PCR testing using the S gene negative results as a proxy measure of infection with the B.1.1.7 variant. It is subject to selection bias in that community-based testing is self-selected or driven by contact tracing. The precise mechanisms responsible for increased mortality associated with the variant remain uncertain but could be related to higher levels of virus replication as well as increased transmissibility. The UK virus variant (B.1.1.7) is fuelling the recent surge in infections across Europe with over million new cases reported last week, an increase of 9% from the previous week.”


Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:

“This new study underpins findings previously considered by NERVTAG, that the B.1.1.7 variant of concern does appear to have a higher mortality rate, compared with the previously-circulating variant. There is already good evidence that this variant is more transmissible.

“This will have contributed to the rises in cases and deaths over the last few months, but it is important to note that when the November lockdown ended, daily figures were then heading in the wrong direction anyway – the variant exacerbated the increases in new daily cases and deaths, but did not cause them.

“This also illustrates the importance of keeping case numbers suppressed, and the futility of those who called for the virus to be able to spread relatively freely, such as supporters of the Great Barrington Declaration. The more COVID-19 there is, the more chance there is of a new variant of concern emerging. This includes the possibilities of variants that can have an impact on the vaccine roll-out. Thus, the recent calls for the UK to open up faster than the plans in the roadmap would be a reckless gamble, and we simply must proceed with caution in the short-term to give ourselves the better prospects in the long-term.”



Risk of mortality in patients infected with SARS-CoV-2 variant of concern 202012/1: matched cohort study’ by Robert Challen et al is published in the BMJ.




All our previous output on this subject can be seen at this weblink:



Declared interests

None received.



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