february 2021 • GOV.UK

NERVTAG report 11 february 2021

New and Emerging Respiratory Virus Threats Advisory Group - NERVTAG


Content curated by:David Rodrigues

Key message

Numa altura em que se estima que variante inglesa B117 se tornará dominante no território nacional damos conta de um relatório do grupo de estudo do SARS-CoV-2 do Governo Inglês - New and Emerging Respiratory Virus Threats Advisory Group - NERVTAG sobre a a severidade do quadro clínico induzido por esta variante. Baseiam-se em várias bases de dados, alertam que as mesmas apresentam limitações inevitáveis e reforçam que é muito provável que a variante B117 esteja associada com maior risco de hospitalização e mortalidade. Sublinham que o risco de mortalidade absoluto por infecção mantem-se baixo.



Pessoas com infecção COVID-19


Consenso de experts


Análise de situação e compilação de análises à situação epidemiológica e relevância clínica da infecção por variantes de SARS-CoV-2


1. On Thursday, 21st January, NERVTAG presented evidence to SAGE of increased disease severity in people infected with variant of concern (VOC) B.1.1.7 compared to people infected with non-VOC virus variants. In that report it was stated that ‘data will accrue in coming weeks, at which time the analyses will become more definitive’. 2. Here we report updated and additional analyses, which together strengthen the earlier finding of increased disease severity in people infected with VOC B.1.1.7 compared to other virus variants. 3. Independent analyses of the risk of hospitalisation and death for S-gene target failure (SGTF; a proxy for VOC B.1.1.7 in the UK) cases and non-SGTF (non-VOC) cases are (also see data table in annex): a. LSHTM: reported that the relative hazard of death within 28 days of test for VOC-infected individuals compared to non-VOC was 1.58 (95%CI 1.40–1.79), or 1.71 (95% CI 1.48- 1.97) if adjustment is made for misclassification of SGTF and missingness of data. b. Imperial College London: mean ratio of case fatality ratio (CFR) for VOC- infected individuals compared to non-VOC was 1.36 (95%CI 1.18-1.56) by a case-control weighting method, 1.29 (95%CI 1.07-1.54) by a standardised CFR method. c. University of Exeter: an updated analysis estimated the mortality hazard ratio for VOC-infected individuals compared to non-VOC was 1.7 (95% CI 1.3 – 2.2) in a matched cohort study. d. Public Health England: an updated matched cohort analysis has reported a death risk ratio for VOC-infected individuals compared to non-VOC of 1.65 (95%CI 1.21-2.25). e. Public Health Scotland: the REACT-SCOT study found that the hazard ratio was 1.08 (95% CI 0.78-1.49) for death and 1.40 (95% CI 1.28-1.53) for death or hospital admission in SGTF compared to non-SGTF cases. f. Public Health Scotland: the EAVE-II study found the risk of being admitted to hospital is higher for cases with SGTF than for those who are S Gene positive - risk Ratio 1.63 (95% CI 1.48, 1.80). The relative risk of death within 28 days of a positive test was 1.37 (95% CI 1.02, 1.84) for SGTF compared to S Gene positive. g. TheHospitalOnsetCovidInfection(HOCI)study:foundtheoverallHRforin- hospital mortality of B.1.1.7 was 1.09 (95% CI 0.86-1.36, P=0.48). Increased mortality was only observed with the VOC in women over 65 years. The overall HR for ITU admission for B.1.1.7 was 1.15 (95% CI 0.86-1.53, P=0.35). h. ICNARC and QRESEARCH: f ound a higher risk of ICU admission for VOC- patients (HR: 1.44; 95% CI: 1.25, 1.67) compared to non-VOC patients and no significant difference in the hazard of ICU mortality between the two groups (HR: 0.94; 95% CI: 0.82, 1.09). i. ONS analysis: found that whilst the hazard ratio suggests that the B.1.1.7 variant is associated with higher risk of all-cause mortality, the number of deaths are too low for reliable inference. j. CO-CIN (hospitalised patients only): found no statistically significant change in in-hospital CFR comparing proven B.1.1.7 (n=32) with non-VOC (n=184) (OR 0.63, 95%CI 0.20 – 1.69). k. CO-CIN (hospitalised patients only): a repeat analysis with an updated dataset did not provide evidence to suggest that the variant of concern is linked to a higher risk of in-hospital case fatality (OR 0.67, 95%CI 0.32, 1.40). l. LSHTM: a population-level analysis at the level of upper-tier local authorities resulted in estimates of a 1.4 (1.3-1.5) times higher number of hospitalisations per case and 1.4 (1.2-1.5) times higher number of fatalities per hospitalisation associated with VOC. 4. There are inevitable limitations to these datasets, including representativeness, power, potential biases in case ascertainment, unmeasured confounders, and secular trends. 5. Whilst studies limited to in-patients did not identify evidence of increased disease severity, this is not incompatible with an overall increase in disease severity. 6. Whilst earlier analyses using linked community testing and mortality data showed comparable increases in case fatality ratios, these were all based on the same datasets, and therefore subject to similar biases reducing the level of certainty in the findings. 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 VOC with increased disease severity. 7. Based on these analyses, it is likely that infection with VOC B.1.1.7 is associated with an increased risk of hospitalisation and death compared to infection with non-VOC viruses. 8. It should be noted that the absolute risk of death per infection remains low.