Hospitalisation and mortality risk of SARS-COV-2 variant omicron sub-lineage BA.2 compared to BA.1 in England.

The Omicron variant of SARS-CoV-2 became the globally dominant variant in early 2022. A sub-lineage of the Omicron variant (BA.2) was identified in England in January 2022. Here, we investigated hospitalisation and mortality risks of COVID-19 cases with the Omicron sub-lineage BA.2 (n = 258,875) compared to BA.1 (n = 984,337) in a large cohort study in England. We estimated the risk of hospital attendance, hospital admission or death using multivariable stratified proportional hazards regression models. After adjustment for confounders, BA.2 cases had lower or similar risks of death (HR = 0.80, 95% CI 0.71-0.90), hospital admission (HR = 0.88, 95% CI 0.83-0.94) and any hospital attendance (HR = 0.98, 95% CI 0.95-1.01). These findings that the risk of severe outcomes following infection with BA.2 SARS-CoV-2 was slightly lower or equivalent to the BA.1 sub-lineage can inform public health strategies in countries where BA.2 is spreading.

Community seroprevalence of SARS-CoV-2 in children and adolescents in England, 2019-2021.

OBJECTIVE: To understand community seroprevalence of SARS-CoV-2 in children and adolescents. This is vital to understanding the susceptibility of this cohort to COVID-19 and to inform public health policy for disease control such as immunisation. DESIGN: We conducted a community-based cross-sectional seroprevalence study in participants aged 0-18 years old recruiting from seven regions in England between October 2019 and June 2021 and collecting extensive demographic and symptom data. Serum samples were tested for antibodies against SARS-CoV-2 spike and nucleocapsid proteins using Roche assays processed at UK Health Security Agency laboratories. Prevalence estimates were calculated for six time periods and were standardised by age group, ethnicity and National Health Service region. RESULTS: Post-first wave (June-August 2020), the (anti-spike IgG) adjusted seroprevalence was 5.2%, varying from 0.9% (participants 10-14 years old) to 9.5% (participants 5-9 years old). By April-June 2021, this had increased to 19.9%, varying from 13.9% (participants 0-4 years old) to 32.7% (participants 15-18 years old). Minority ethnic groups had higher risk of SARS-CoV-2 seropositivity than white participants (OR 1.4, 95% CI 1.0 to 2.0), after adjusting for sex, age, region, time period, deprivation and urban/rural geography. In children <10 years, there were no symptoms or symptom clusters that reliably predicted seropositivity. Overall, 48% of seropositive participants with complete questionnaire data recalled no symptoms between February 2020 and their study visit. CONCLUSIONS: Approximately one-third of participants aged 15-18 years old had evidence of antibodies against SARS-CoV-2 prior to the introduction of widespread vaccination. These data demonstrate that ethnic background is independently associated with risk of SARS-CoV-2 infection in children. TRIAL REGISTRATION NUMBER: NCT04061382.

A methodological framework for model selection in interrupted time series studies.

Interrupted time series (ITS) is a powerful and increasingly popular design for evaluating public health and health service interventions. The design involves analyzing trends in the outcome of interest and estimating the change in trend following an intervention relative to the counterfactual (the expected ongoing trend if the intervention had not occurred). There are two key components to modeling this effect: first, defining the counterfactual; second, defining the type of effect that the intervention is expected to have on the outcome, known as the impact model. The counterfactual is defined by extrapolating the underlying trends observed before the intervention to the postintervention period. In doing this, authors must consider the preintervention period that will be included, any time-varying confounders, whether trends may vary within different subgroups of the population and whether trends are linear or nonlinear. Defining the impact model involves specifying the parameters that model the intervention, including for instance whether to allow for an abrupt level change or a gradual slope change, whether to allow for a lag before any effect on the outcome, whether to allow a transition period during which the intervention is being implemented, and whether a ceiling or floor effect might be expected. Inappropriate model specification can bias the results of an ITS analysis and using a model that is not closely tailored to the intervention or testing multiple models increases the risk of false positives being detected. It is important that authors use substantive knowledge to customize their ITS model a priori to the intervention and outcome under study. Where there is uncertainty in model specification, authors should consider using separate data sources to define the intervention, running limited sensitivity analyses or undertaking initial exploratory studies.

The impact of new national guidance for the public health management of enteric fever in England.

OBJECTIVES: New guidance was published in England in February 2012 to support the public health management of enteric fever and reduce the risks of secondary transmission. The new guidance was evaluated to assess: STUDY DESIGN: Quantitative and qualitative evaluation of the implementation of new public health guidance. METHODS: A qualitative review of all non-travel-related cases from February 2010 to January 2014 to compare the risk of secondary transmission before and after the guidance introduction; an audit of clearance sampling for each case and their contacts reported in London from February 2012-January 2015 to compare with a previous London audit; and an online user survey in November 2014. RESULTS: The proportions of non-travel cases reported before and after the introduction of the new guidance were similar, 6% in 2010-2012 compared to 7% in 2012-2014 (P = 0.33). There was a 32% reduction in the number of clearance samples required for cases and the estimated period of exclusion from work or school was reduced from 54 days to 16 days. Compliance in case clearance improved from 53% to 90% and contact screening compliance improved from 42% to 80%. The targeted screening of contacts led to a significantly higher positive yield (3.6% from 1.5%, P = 0.003). All symptomatic co-travellers presented to a healthcare professional, suggesting that screening could be restricted to those in risk groups for transmission. Feedback from users highlighted additional areas, such as management of large organised groups of co-travellers and those diagnosed abroad, which has informed the update of the national guidance. CONCLUSIONS: The new guidance has not led to an increase in secondary transmission of enteric fever in England and findings have been used to inform an update of the guidance. The new guidance also represents a reduced burden of investigation and thus a likely reduced cost to patients, healthcare professionals, laboratories and environmental health officers.

Wet air oxidation of oily wastes generated aboard ships: kinetic modeling.

Ships are floating industrial plants which generate great amounts of toxic and hazardous wastes. Nevertheless, a feasible model for the management of such wastes has not been developed yet. This work studies the feasibility of treating those wastes aboard the ship by means of aqueous oxidation at high pressures and temperatures. Wet air oxidation has proved to be a very efficient technology for the treatment of those residual currents, resulting in destruction efficiencies of greater than 90% of initial COD and 99.9% of oil/greases content. A kinetic model for the oxidation process, based on a series-parallel reaction pathway, is proposed and is shown to fit the experimental results.