Developing influenza and respiratory syncytial virus activity thresholds for syndromic surveillance in England.

Influenza and respiratory syncytial virus (RSV) are common causes of respiratory tract infections and place a burden on health services each winter. Systems to describe the timing and intensity of such activity will improve the public health response and deployment of interventions to these pressures. Here we develop early warning and activity intensity thresholds for monitoring influenza and RSV using two novel data sources: general practitioner out-of-hours consultations (GP OOH) and telehealth calls (NHS 111). Moving Epidemic Method (MEM) thresholds were developed for winter 2017-2018. The NHS 111 cold/flu threshold was breached several weeks in advance of other systems. The NHS 111 RSV epidemic threshold was breached in week 41, in advance of RSV laboratory reporting. Combining the use of MEM thresholds with daily monitoring of NHS 111 and GP OOH syndromic surveillance systems provides the potential to alert to threshold breaches in real-time. An advantage of using thresholds across different health systems is the ability to capture a range of healthcare-seeking behaviour, which may reflect differences in disease severity. This study also provides a quantifiable measure of seasonal RSV activity, which contributes to our understanding of RSV activity in advance of the potential introduction of new RSV vaccines.

Developing and validating a new national remote health advice syndromic surveillance system in England.

Background: Public Health England (PHE) coordinates a suite of real-time national syndromic surveillance systems monitoring general practice, emergency department and remote health advice data. We describe the development and informal evaluation of a new syndromic surveillance system using NHS 111 remote health advice data. Methods: NHS 111 syndromic indicators were monitored daily at national and local level. Statistical models were applied to daily data to identify significant exceedances; statistical baselines were developed for each syndrome and area using a multi-level hierarchical mixed effects model. Results: Between November 2013 and October 2014, there were on average 19 095 NHS 111 calls each weekday and 43 084 each weekend day in the PHE dataset. There was a predominance of females using the service (57%); highest percentage of calls received was in the age group 1-4 years (14%). This system was used to monitor respiratory and gastrointestinal infections over the winter of 2013-14, the potential public health impact of severe flooding across parts of southern England and poor air quality episodes across England in April 2014. Conclusions: This new system complements and supplements the existing PHE syndromic surveillance systems and is now integrated into the routine daily processes that form this national syndromic surveillance service.

Internet-based remote health self-checker symptom data as an adjuvant to a national syndromic surveillance system.

Syndromic surveillance is an innovative surveillance tool used to support national surveillance programmes. Recent advances in the use of internet-based health data have demonstrated the potential usefulness of these health data; however, there have been limited studies comparing these innovative health data to existing established syndromic surveillance systems. We conducted a retrospective observational study to assess the usefulness of a national internet-based 'symptom checker' service for use as a syndromic surveillance system. NHS Direct online data were extracted for 1 August 2012 to 1 July 2013; a time-series analysis on the symptom categories self-reported by online users was undertaken and compared to existing telehealth syndromic data. There were 3·37 million online users of the internet-based self-checker compared to 1·43 million callers to the telephone triage health service. There was a good correlation between the online and telephone triage data for a number of syndromic indicators including cold/flu, difficulty breathing and eye problems; however, online data appeared to provide additional early warning over telephone triage health data. This assessment has illustrated some potential benefit of using internet-based symptom-checker data and provides the basis for further investigating how these data can be incorporated into national syndromic surveillance programmes.

Developing a new syndromic surveillance system for the London 2012 Olympic and Paralympic Games.

Syndromic surveillance is vital for monitoring public health during mass gatherings. The London 2012 Olympic and Paralympic Games represents a major challenge to health protection services and community surveillance. In response to this challenge the Health Protection Agency has developed a new syndromic surveillance system that monitors daily general practitioner out-of-hours and unscheduled care attendances. This new national system will fill a gap identified in the existing general practice-based syndromic surveillance systems by providing surveillance capability of general practice activity during evenings/nights, over weekends and public holidays. The system will complement and supplement the existing tele-health phone line, general practitioner and emergency department syndromic surveillance systems. This new national system will contribute to improving public health reassurance, especially to meet the challenges of the London 2012 Olympic and Paralympic Games.

Syndromic surveillance to assess the potential public health impact of the Icelandic volcanic ash plume across the United Kingdom, April 2010.

The Health Protection Agency and Health Protection Scotland used existing syndromic surveillance systems to monitor community health in the UK following the volcanic eruption in Iceland in April 2010.

Vomiting calls to NHS Direct provide an early warning of norovirus outbreaks in hospitals.

A wintertime peak of norovirus activity occurs each year, affecting institutions including schools and hospitals. Traditional laboratory and outbreak surveillance systems for norovirus are too vulnerable to reporting delay to act as a timely signal of activity in the community. Calls to the National Health Service (NHS) telephone service NHS Direct have the potential to be an early warning tool for public health purposes. We investigated whether NHS Direct vomiting calls can be used as a reliable indicator of norovirus activity and, if so, whether the increase in calls precedes the epidemic of hospital outbreaks. Laboratory reports were used as the reference standard to define the norovirus season. From 2004 to 2008, four series of NHS Direct call data were compared with laboratory data held at the Health Protection Agency Centre for Infections in order to identify the best predictor of the season start. The four series included: (1) modelled and extracted the proportion of calls likely to be for 'non-rotavirus' gastroenteritis; (2) the mean proportion of weekly vomiting calls in children aged <5 years; (3) the mean proportion of weekly vomiting calls for all ages; (4) the slope of the vomiting call data. Issuing an alert when 4% or more of NHS Direct vomiting calls in all age groups for two weeks in a row should provide up to four weeks' advance warning of forthcoming norovirus pressures on the health service.

Linking syndromic surveillance with virological self-sampling.

Calls to a UK national telephone health helpline (NHS Direct) have been used for syndromic surveillance, aiming to provide early warning of rises in community morbidity. We investigated whether self-sampling by NHS Direct callers could provide viable samples for influenza culture. We recruited 294 NHS Direct callers and sent them self-sampling kits. Callers were asked to take a swab from each nostril and post them to the laboratory. Forty-two per cent of the samples were returned, 16.2% were positive on PCR for influenza (16 influenza A(H3N2), three influenza A (H1N1), four influenza B) and eight for RSV (5.6%). The mean time between the NHS Direct call and laboratory analysis was 7.4 days. These samples provided amongst the earliest influenza reports of the season, detected multiple influenza strains, and augmented a national syndromic surveillance system. Self-sampling is a feasible method of enhancing community-based surveillance programmes for detection of influenza.

A national syndromic surveillance system for England and Wales using calls to a telephone helpline.

Routine primary care data provide the means to monitor a variety of syndromes which could give early warning of health protection issues. In the United Kingdom, a national syndromic surveillance system, operated jointly by the UK Health Protection Agency (HPA) and NHS Direct (a national telephone health helpline), examines symptoms reported to NHS Direct. The aim of the system is to identify an increase in syndromes indicative of common infections and diseases, or the early stages of illness caused by the deliberate release of a biological or chemical agent. Data relating to 11 key symptoms/syndromes are received electronically from all 22 NHS Direct call centres covering England and Wales and analysed by the HPA on a daily basis. Statistically significant excesses in calls are automatically highlighted and assessed by a multi-disciplinary team. Although the surveillance system has characterised many sudden rises in syndromes reported to NHS Direct, no evidence of a biological or chemical attack has been detected. Benefits of this work, however, are early warning and tracking of rises in community morbidity (e.g. influenza-like illness, heatstroke); providing reassurance during times of perceived high risk (e.g. after the 7 July 2005 London bombs and December 2005 Buncefield oil depot fire); and timely surveillance data for influenza pandemic planning and epidemic modeling.

Physical dependence on diazepam.

This article describes several cases of withdrawal symptoms following diazepam therapy which suggest physical dependence following usual therapeutic dosage.