Influenza vaccine effectiveness against hospitalisation due to laboratory-confirmed influenza in children in England in the 2015-2016 influenza season - a test-negative case-control study.

England has recently started a new paediatric influenza vaccine programme using a live-attenuated influenza vaccine (LAIV). There is uncertainty over how well the vaccine protects against more severe end-points. A test-negative case-control study was used to estimate vaccine effectiveness (VE) in vaccine-eligible children aged 2-16 years of age in preventing laboratory-confirmed influenza hospitalisation in England in the 2015-2016 season using a national sentinel laboratory surveillance system. Logistic regression was used to estimate the VE with adjustment for sex, risk-group, age group, region, ethnicity, deprivation and month of sample collection. A total of 977 individuals were included in the study (348 cases and 629 controls). The overall adjusted VE for all study ages and vaccine types was 33.4% (95% confidence interval (CI) 2.3-54.6) after adjusting for age group, sex, index of multiple deprivation, ethnicity, region, sample month and risk group. Risk group was shown to be an important confounder. The adjusted VE for all influenza types for the live-attenuated vaccine was 41.9% (95% CI 7.3-63.6) and 28.8% (95% CI -31.1 to 61.3) for the inactivated vaccine. The study provides evidence of the effectiveness of influenza vaccination in preventing hospitalisation due to laboratory-confirmed influenza in children in 2015-2016 and continues to support the rollout of the LAIV childhood programme.

Assessing the severity of influenza: a role for longitudinal telephone surveys?

During the 2009 influenza pandemic, a rapid assessment of disease severity was a challenge as a significant proportion of cases did not seek medical care; care-seeking behaviour changed and the proportion asymptomatic was unknown. A random-digit-dialling telephone survey was undertaken during the 2011/12 winter season in England and Wales to address the feasibility of answering these questions. A proportional quota sampling strategy was employed based on gender, age group, geographical location, employment status and level of education. Households were recruited pre-season and re-contacted immediately following peak seasonal influenza activity. The pre-peak survey was undertaken in October 2011 with 1061 individuals recruited and the post-peak telephone survey in March 2012. Eight hundred and thirty-four of the 1061 (78.6%) participants were successfully re-contacted. Their demographic characteristics compared well to national census data. In total, 8.4% of participants self-reported an influenza-like illness (ILI) in the previous 2 weeks, with 3.2% conforming to the World Health Organization (WHO) ILI case definition. In total, 29.6% of the cases reported consulting their general practitioner. 54.1% of the 1061 participants agreed to be re-contacted about providing biological samples. A population-based cohort was successfully recruited and followed up. Longitudinal survey methodology provides a practical tool to assess disease severity during future pandemics.

Developing a system to estimate the severity of influenza infection in England: findings from a hospital-based surveillance system between 2010/2011 and 2014/2015.

The UK Severe Influenza Surveillance System (USISS) was established following the 2009 influenza pandemic to monitor severe seasonal influenza. This article describes the severity of influenza observed in five post-2009 pandemic seasons in England. Two key measures were used to assess severity: impact measured through the cumulative incidence of laboratory-confirmed hospitalised influenza and case severity through the proportion of confirmed hospitalised cases admitted into intensive care units (ICU)/high dependency units (HDU). The impact of influenza varied by subtype and age group across the five seasons with the highest crude cumulative hospitalisation incidence for influenza A/H1N1pdm09 cases in 2010/2011 and in 0-4 year olds each season for all-subtypes. Case severity also varied by subtype and season with a higher hospitalisation: ICU ratio for A/H1N1pdm09 and older age groups (older than 45 years). The USISS system provides a tool for measuring severity of influenza each year. Such seasonal surveillance can provide robust baseline estimates to allow for rapid assessment of the severity of seasonal and emerging influenza viruses.

Detection of varying influenza circulation within England in 2012/13: informing antiviral prescription and public health response.

BACKGROUND: Subnational variation of 2009 pandemic influenza activity in England has been reported; however, little work has been published on this topic for seasonal influenza. If variation is present, this knowledge may assist with both identifying the onset of influenza epidemics, informing community antiviral prescription and local health planning. METHODS: An end-of-season analysis of influenza surveillance systems (acute respiratory outbreaks, primary care consultations, virological testing, influenza-confirmed secondary care admissions and excess all-cause mortality) was undertaken at national and subnational levels for 2012/13 when influenza B and A(H3N2) dominated. RESULTS: National community antiviral prescription was recommended in Week 51 following national threshold exceedance. However, this was preceded up to 2 weeks by subnational influenza activity in 2/9 regions in England. Regional variation in circulation of influenza subtypes was observed and severe influenza surveillance data sources were able to monitor the subnational impact. CONCLUSIONS: Evidence of virological activity in two or more regions above a threshold indicated the onset of the 2012/13 season. Subnational thresholds should be determined and evaluated in order to improve timeliness of the national antiviral alert. During the season, outputs should be reported at levels that can inform local public health responses and variation considered when retrospectively evaluating the impact of interventions.

Estimating vaccine effectiveness against severe influenza in England and Scotland 2011/2012: applying the screening method to data from intensive care surveillance systems.

Methods for estimating vaccine effectiveness (VE) against severe influenza are not well established. We used the screening method to estimate VE against influenza resulting in intensive care unit (ICU) admission in England and Scotland in 2011/2012. We extracted data on confirmed influenza ICU cases from severe influenza surveillance systems, and obtained their 2011/2012 trivalent influenza vaccine (TIV) status from primary care. We compared case vaccine uptake with population vaccine uptake obtained from routine monitoring systems, adjusting for age group, specific risk group, region and week. Of 60 influenza ICU cases reported, vaccination status was available for 56 (93%). Adjusted VE against ICU admission for those aged ≥ 65 years was -10% [95% confidence interval (CI) -207 to 60], consistent with evidence of poor protection from the 2011/2012 TIV in 2011/2012. Adjusted VE for those aged <65 years in risk groups was -296% (95% CI -930 to -52), suggesting significant residual confounding using the screening method in those subject to selective vaccination.

Severe respiratory illness caused by a novel coronavirus, in a patient transferred to the United Kingdom from the Middle East, September 2012.

Coronaviruses have the potential to cause severe transmissible human disease, as demonstrated by the severe acute respiratory syndrome (SARS) outbreak of 2003. We describe here the clinical and virological features of a novel coronavirus infection causing severe respiratory illness in a patient transferred to London, United Kingdom, from the Gulf region of the Middle East.

The United Kingdom public health response to an imported laboratory confirmed case of a novel coronavirus in September 2012.

On 22 September 2012, a novel coronavirus, very closely related to that from a fatal case in Saudi Arabia three months previously, was detected in a previously well adult transferred to intensive care in London from Qatar with severe respiratory illness. Strict respiratory isolation was instituted. Ten days after last exposure, none of 64 close contacts had developed severe disease, with 13 of 64 reporting mild respiratory symptoms. The novel coronavirus was not detected in 10 of 10 symptomatic contacts tested.