The government advisory body, NERVTAG, in an assessment of a COVID-19 variant identified in the UK, suggests that it may be more deadly.
The new and emerging respiratory virus threats advisory group (NERVTAG), is an expert committee, which, as the name suggests, provides a scientific risk assessment and mitigation advice on the potential threats caused by new and emerging respiratory viruses. With reports in the media highlighting the threats posed by a COVID-19 variant, or as it has become known, a variant of concern (VOC), NERVTAG has released details of their own assessment of this mutant strain of the virus which was first identified in December 2020. In the process of identifying COVID-19, a diagnostic assay which targets three genes: ORF1ab, N and S genes, is commonly used. Thus, in the absence of the S gene, the assay will generate a negative result and the NERVTAG paper refers to the VOC being associated with s-gene target failure (SGTF). This negative result serves as a proxy for the VOC, which is also referred to as B.1.1.7. The latest NERVTAG paper assesses several independent studies which have examined differences in mortality associated with the VOC compared to the original strain.
The NERVTAG paper describes the findings from several independent analyses. In one analysis from the London school of hygiene and tropical medicine, it was reported that the relative hazard of death within 28 days of infection with VOC-infected individuals compared to non-VOC was 35% higher (hazard ratio, HR = 1.35, 95% CI 1.08 to 1.68). This was similar to data provided by Imperial College, London, in which the hazard ratio was 1.29. In contrast, data from a team at Exeter university, indicated that the estimated hazard ratio (HR) was 1.91 (95% CI 1.35 to 2.71). Finally, data from Public Health England, has estimated the HR to be 1.65 (95% CI 1.21 to 2.25). However, NERVTAG does note that these analyses are based on a limited subset of total deaths and therefore subject to some uncertainty. In addition, NERVTAG also noted that there is currently no evidence of an increased risk of death among those hospitalised with VOC B.1.1.7.
While accepting the limitations of the available evidence, based on the totality of the available evidence, the NERVTAG paper concludes that “there is a realistic probability that infection with VOC B.1.1.7 is associated with an increased risk of death compared to infection with non-VOC viruses.”
The full NERVTAG paper can be found here.