A Bayesian multivariate factor analysis model for causal inference using time-series observational data on mixed outcomes.

Assessing the impact of an intervention by using time-series observational data on multiple units and outcomes is a frequent problem in many fields of scientific research. Here, we propose a novel Bayesian multivariate factor analysis model for estimating intervention effects in such settings and develop an efficient Markov chain Monte Carlo algorithm to sample from the high-dimensional and nontractable posterior of interest. The proposed method is one of the few that can simultaneously deal with outcomes of mixed type (continuous, binomial, count), increase efficiency in the estimates of the causal effects by jointly modeling multiple outcomes affected by the intervention, and easily provide uncertainty quantification for all causal estimands of interest. Using the proposed approach, we evaluate the impact that Local Tracing Partnerships had on the effectiveness of England's Test and Trace programme for COVID-19.

Risk of transmission of SARS-CoV-2 on international flights, a retrospective cohort study using national surveillance data in England.

BACKGROUND: It is not yet fully understood to what extent in-flight transmission contributed to the spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). This study aimed to determine the occurrence and extent of SARS-CoV-2 transmission in-flight and assess factors associated with transmission risk to inform future control strategies. METHODS: Retrospective cohort study using data obtained from contact tracing of international flights arriving in England between 02/08/2021-15/10/2021. Transmission risk was estimated by calculating the secondary attack rate (SAR). Univariable and multivariable analyses of the SAR by specific risk factors was undertaken, including: number of in-flight index cases; number of symptomatic index cases; contact vaccination status; flight duration; proximity to the index case(s); contact age. RESULTS: 11,307 index cases linked to 667,849 contacts with 5,289 secondary cases reported. In-flight SAR was 0.79% (95% CI: 0.77-0.81). Increasing numbers of symptomatic cases (when > 4 index cases compared to one index case aOR 1.85; 95% CI: 1.40-2.44) and seating proximity to an index case (seated within compared to outside of two rows OR 1.82; 95% CI: 1.50-2.22) were associated with increased risk of secondary cases. Full vaccination history was protective (aOR 0.52; 95% CI: 0.47-0.57). CONCLUSIONS: This study confirms that in-flight transmission of SARS-CoV-2 occurred. There are factors associated with increased risk of infection. Contact tracing identified exposed persons who subsequently developed infection. A targeted approach to contact tracing passengers with the highest exposure risk could be an effective use of limited public health resources.

A case of swine influenza A(H1N2)v in England, November 2023.

Under International Health Regulations from 2005, a human infection caused by a novel influenza A virus variant is considered an event that has potential for high public health impact and is immediately notifiable to the World Health Organisation. We here describe the clinical, epidemiological and virological features of a confirmed human case of swine influenza A(H1N2)v in England detected through community respiratory virus surveillance. Swabbing and contact tracing helped refine public health risk assessment, following this unusual and unexpected finding.

Tailoring the Use of Central Pancreatectomy Through Prediction Models for Major Morbidity and Postoperative Diabetes: International Retrospective Multicenter Study.

OBJECTIVE: To develop a prediction model for major morbidity and endocrine dysfunction after CP which could help in tailoring the use of this procedure. SUMMARY BACKGROUND DATA: Central pancreatectomy (CP) is a parenchyma-sparing alternative to distal pancreatectomy for symptomatic benign and pre-malignant tumors in body and neck of the pancreas CP lowers the risk of new-onset diabetes and exocrine pancreatic insufficiency compared to distal pancreatectomy but it is thought to increase the risk of short-term complications including postoperative pancreatic fistula (POPF). METHODS: International multicenter retrospective cohort study including patients from 51 centers in 19 countries (2010-2021). Primary endpoint was major morbidity. Secondary endpoints included POPF grade B/C, endocrine dysfunction, and the use of pancreatic enzymes. Two risk model were designed for major morbidity and endocrine dysfunction utilizing multivariable logistic regression and internal and external validation. RESULTS: 838 patients after CP were included (301 (36%) minimally invasive) and major morbidity occurred in 248 (30%) patients, POPF B/C in 365 (44%), and 30-day mortality in 4 (1%). Endocrine dysfunction in 91 patients (11%) and use of pancreatic enzymes in 108 (12%). The risk model for major morbidity included male sex, age, BMI, and ASA score≥3. The model performed acceptable with an area under curve (AUC) of 0.72(CI:0.68-0.76). The risk model for endocrine dysfunction included higher BMI and male sex and performed well (AUC:0.83 (CI:0.77-0.89)). CONCLUSIONS: The proposed risk models help in tailoring the use of CP in patients with symptomatic benign and premalignant lesions in the body and neck of the pancreas and are readily available via www.pancreascalculator.com.

Understanding the impact of the COVID-19 pandemic response on GI infection surveillance trends in England, January 2020-April 2022.

Stepwise non-pharmaceutical interventions and health system changes implemented as part of the COVID-19 response have had implications on the incidence, diagnosis, and reporting of other communicable diseases. Here, we established the impact of the COVID-19 outbreak response on gastrointestinal (GI) infection trends using routinely collected surveillance data from six national English laboratory, outbreak, and syndromic surveillance systems using key dates of governmental policy to assign phases for comparison between pandemic and historic data. Following decreases across all indicators during the first lockdown (March-May 2020), bacterial and parasitic pathogens associated with foodborne or environmental transmission routes recovered rapidly between June and September 2020, while those associated with travel and/or person-to-person transmission remained lower than expected for 2021. High out-of-season norovirus activity was observed with the easing of lockdown measures between June and October 2021, with this trend reflected in laboratory and outbreak systems and syndromic surveillance indicators. Above expected increases in emergency department (ED) attendances may have reflected changes in health-seeking behaviour and provision. Differential reductions across specific GI pathogens are indicative of the underlying routes of transmission. These results provide further insight into the drivers for transmission, which can help inform control measures for GI infections.

Mpox knowledge, behaviours and barriers to public health measures among gay, bisexual and other men who have sex with men in the UK: a qualitative study to inform public health guidance and messaging.

BACKGROUND: The 2022-23 mpox epidemic is the first-time sustained community transmission had been reported in countries without epidemiological links to endemic areas. During that period, the outbreak almost exclusively affected sexual networks of gay, bisexual, or other men who have sex with men (GBMSM) and people living with HIV. In efforts to control transmission, multiple public health measures were implemented, including vaccination, contact tracing and isolation. This study examines knowledge, attitudes, and perceptions of mpox among a sample of GBMSM during the 2022-23 outbreak in the UK, including facilitators for and barriers to the uptake of public health measures. METHODS: Interviews were conducted with 44 GBMSM between May and December 2022. Data were analysed using reflexive thematic analysis. Positive and negative comments pertaining to public health measures were collated in a modified version of a 'table of changes' to inform optimisations to public health messages and guidance. RESULTS: Most interviewees were well informed about mpox transmission mechanisms and were either willing to or currently adhering to public health measures, despite low perceptions of mpox severity. Measures that aligned with existing sexual health practices and norms were considered most acceptable. Connections to GBMSM networks and social media channels were found to increase exposure to sexual health information and norms influencing protective behaviours. Those excluded or marginalized from these networks found some measures challenging to perform or adhere to. Although social media was a key mode of information sharing, there were preferences for timely information from official sources to dispel exaggerated or misleading information. CONCLUSIONS: There are differential needs, preferences, and experiences of GBMSM that limit the acceptability of some mitigation and prevention measures. Future public health interventions and campaigns should be co-designed in consultation with key groups and communities to ensure greater acceptability and credibility in different contexts and communities.

Understanding adherence to self-isolation in the first phase of the COVID-19 pandemic in England: a cross-sectional mixed-methods study.

BACKGROUND: During the early "containment" phase of the COVID-19 response in England (January-March 2020), contact tracing was managed by Public Health England (PHE). Adherence to self-isolation during this phase and how people were making those decisions has not previously been determined. The aim of this study was to gain a better understanding of decisions around adherence to self-isolation during the first phase of the COVID-19 response in England. METHODS: A mixed-methods cross sectional study was conducted, including an online survey and qualitative interviews. The overall pattern of adherence was described as never leaving home, leaving home for lower-contact reasons and leaving home for higher-contact reasons. Fisher's exact test was used to test associations between adherence and potentially predictive binary factors. Factors showing evidence of association overall were then considered in relation to the three aspects of adherence individually. Qualitative data were analysed using inductive thematic analysis. RESULTS: Of 250 respondents who were advised to self-isolate, 63% reported not leaving home at all during their isolation period, 20% reported leaving only for lower-contact activities (dog walking or exercise) and 16% reported leaving for higher-contact, and therefore higher-risk, reasons. Factors associated with adherence to never going out included: the belief that following isolation advice would save lives, experiencing COVID-19 symptoms, being advised to stay in their room, having help from outside and having regular contact by text message from PHE. Factors associated with non-adherence included being angry about the advice to isolate, being unable to get groceries delivered and concerns about losing touch with friends and family. Interviews highlighted that a sense of duty motivated people to adhere to isolation guidance and where people did leave their homes, these decisions were based on rational calculations of the risk of transmission - people would only leave their homes when they thought they were unlikely to come into contact with others. CONCLUSIONS: Understanding adherence to isolation and associated reasoning during the early stages of the pandemic is essential to pandemic preparedness for future emerging infectious disease outbreaks. Individuals make complex decisions around adherence by calibrating transmission risks, therefore treating adherence as binary should be avoided.

Duodenal diastatic perforation due to double gastric and jejunal trichobezoar in a patient with Rapunzel syndrome.

Rapunzel syndrome is a rare clinical entity in which a trichobezoar is produced by the ingestion of hair at the gastric level, extending in the form of a tail towards the duodenum. It occurs in young patients with trichotillomania and trichophagia. We present the case of a 24-year-old woman with a history of anxiety without treatment, who for 10 years presented trichotillomania and trichophagia, producing a picture of intestinal obstruction that required surgical intervention, evidencing a giant Trichobezoar throughout the gastric cavity and one jejunum associated with diastatic perforation. duodenal.

Workplace exposures associated with COVID-19: evidence from a case-control study with multiple sampling periods in England, August-October 2020.

We investigated risk factors associated with COVID-19 by conducting a retrospective, frequency-matched case-control study, with three sampling periods (August-October 2020). We compared cases completing routine contact tracing to asymptomatic population controls. Multivariable analyses estimated adjusted odds ratios (aORs) for non-household community settings. Meta-analyses using random effects provided pooled odds ratios (pORs). Working in healthcare (pOR 2.87; aORs 2.72, 2.81, 3.08, for study periods 1-3 respectively), social care (pOR 4.15; aORs 2.46, 5.06, 5.41, for study periods 1-3 respectively) or hospitality (pOR 2.36; aORs 2.01, 2.54, 2.63, for study periods 1-3 respectively) were associated with increased odds of being a COVID-19 case. Additionally, working in bars, pubs and restaurants, warehouse settings, construction, educational settings were significantly associated. While definitively determining where transmission occurs is impossible, we provide evidence that in certain sectors, the impact of mitigation measures may only be partial and reinforcement of measures should be considered in these settings.

Exploration of attitudes regarding uptake of COVID-19 vaccines among vaccine hesitant adults in the UK: a qualitative analysis.

BACKGROUND: The aim of this work was to explore barriers and facilitators to uptake of COVID-19 vaccines and to explore views and reactions to efforts to improve vaccine uptake among vaccine hesitant individuals. METHODS: Semi-structured interviews were conducted with people between the age of 18-29 years who had not had a COVID-19 vaccine, and those between 30 and 49 years who had not had a second dose of a COVID-19 vaccine. RESULTS: A total of 70 participants took part in the study, 35 participants had received one dose, and 35 had not been vaccinated. Participants described a willingness to be vaccinated to keep themselves and those around them safe and to avoid restrictions. Barriers to uptake included: (1) perceived lack of need for COVID-19 vaccinations, (2) concerns about the efficacy of vaccinations, (3) concerns about safety, and (4) access issues. Uptake appeared to be influenced by age and health status, trust in government, and knowledge and understanding of science. Introduction of vaccine passes may provide a motive for having a vaccine but may be viewed as coercive. CONCLUSION: Participants were hesitant, rather than opposed, and had questions about their need for, and the safety and efficacy of the vaccine. Young people did not consider themselves to be at risk of becoming ill from COVID-19, did not think the vaccination was effective in preventing transmission, and did not think sufficient research had been conducted regarding possible long-term side-effects. Concerns were exacerbated by a lack of trust in government, and misunderstanding of science. To promote uptake, public health campaigns should focus on the provision of information from trusted sources that explains the benefits of vaccination and addresses safety concerns more effectively. To overcome inertia in people with low levels of motivation to be vaccinated, appointments must be easily accessible.

Exploring the impact of shielding advice on the wellbeing of individuals identified as clinically extremely vulnerable amid the COVID-19 pandemic: a mixed-methods evaluation.

BACKGROUND: The national shielding programme was introduced by UK Government at the beginning of the COVID-19 pandemic, with individuals identified as clinically extremely vulnerable (CEV) offered advice and support to stay at home and avoid all non-essential contact. This study aimed to explore the impact and responses of "shielding" on the health and wellbeing of CEV individuals in Southwest England during the first COVID-19 lockdown. METHODS: A two-stage mixed methods study, including a structured survey (7 August-23 October 2020) and semi-structured telephone interviews (26 August-30 September 2020) with a sample of individuals who had been identified as CEV and advised to "shield" by Bristol, North Somerset & South Gloucestershire (BNSSG) Clinical Commissioning Group (CCG). RESULTS: The survey was completed by 203 people (57% female, 54% > 69 years, 94% White British, 64% retired) in Southwest England identified as CEV by BNSSG CCG. Thirteen survey respondents participated in follow-up interviews (53% female, 40% > 69 years, 100% White British, 61% retired). Receipt of 'official' communication from NHS England or General Practitioner (GP) was considered by participants as the legitimate start of shielding. 80% of survey responders felt they received all relevant advice needed to shield, yet interviewees criticised the timing of advice and often sought supplementary information. Shielding behaviours were nuanced, adapted to suit personal circumstances, and waned over time. Few interviewees received community support, although food boxes and informal social support were obtained by some. Worrying about COVID-19 was common for survey responders (90%). Since shielding had begun, physical and mental health reportedly worsened for 35% and 42% of survey responders respectively. 21% of survey responders scored ≥ 10 on the PHQ-9 questionnaire indicating possible depression and 15% scored ≥ 10 on the GAD-7 questionnaire indicating possible anxiety. CONCLUSIONS: This research highlights the difficulties in providing generic messaging that is applicable and appropriate given the diversity of individuals identified as CEV and the importance of sharing tailored and timely advice to inform shielding decisions. Providing messages that reinforce self-determined action and assistance from support services could reduce the negative impact of shielding on mental health and feelings of social isolation.

A qualitative process analysis of daily contact testing as an alternative to self-isolation following close contact with a confirmed carrier of SARS-CoV-2.

BACKGROUND: In July 2021, a randomised controlled trial was conducted to compare the effect on SARS-CoV-2 transmission of seven days of Daily Contact Testing (DCT) using Lateral Flow Test (LFT) and two Polymerase Chain Reaction (PCR) tests as an alternative to 10 days of standard self-isolation with one PCR, following close contact with a SARS-CoV-2 carrier. In this qualitative study, we used a nested process evaluation to aid interpretation of the trial and provide insight into factors influencing use of tests, understanding of test results, and how tests were used to inform behavioural decisions. METHODS: Interviews were conducted with 60 participants (42 randomised to DCT and 18 randomised to self-isolation) who had been in close contact with a confirmed SARS-CoV-2 carrier and had consented to take part in the trial. RESULTS: Data were organised into three overarching themes: (1) assessing the risks and benefits of DCT (2) use of testing during the study period and (3) future use of testing. Attitudes toward DCT as an alternative to self-isolation and behaviour during the testing period appeared to be informed by an assessment of the associated risks and benefits. Participants reported how important it was for them to avoid isolation, how necessary self-isolation was considered to be, and the ability of LFTs to detect infection. Behaviour during the testing period was modified to reduce risks and harms as much as possible. Testing was considered a potential compromise, reducing both risk of transmission and the negative impact of self-isolation, and was regarded as a way to return to normal. CONCLUSION: Participants in this study viewed DCT as a sensible, feasible, and welcome means of avoiding unnecessary self-isolation. Although negative LFTs provided reassurance, most people still restricted their activity as recommended. DCT was also highly valued by those in vulnerable households as a means of providing reassurance of the absence of infection and as an important means of detecting infection and prompting self-isolation when necessary.

A case of avian influenza A(H5N1) in England, January 2022.

On 5 January 2022, high pathogenicity avian influenza A(H5N1) was confirmed in an individual who kept a large flock of ducks at their home in England. The individual remained asymptomatic. H5N1 was confirmed in 19/20 sampled live birds on 22 December 2021. Comprehensive contact tracing (n = 11) revealed no additional primary cases or secondary transmissions. Active surveillance of exposed individuals is essential for case identification. Asymptomatic swabbing helped refine public health risk assessment and facilitated case management given changes in avian influenza epidemiology.

Evaluation of National Event-Based Surveillance, Nigeria, 2016-2018.

Nigeria Centres for Disease Control and Prevention established an event-based surveillance (EBS) system in 2016 to supplement traditional surveillance structures. The EBS system is comprised of an internet-based data mining tool and a call center. To evaluate the EBS system for usefulness, simplicity, acceptability, timeliness, and data quality, we performed a descriptive analysis of signals received during September 2017-June 2018. We used questionnaires, semistructured interviews, and direct observation to collect information from EBS staff. Amongst 43,631 raw signals detected, 138 (0.3%) were escalated; 63 (46%) of those were verified as events, including 25 Lassa fever outbreaks and 13 cholera outbreaks. Interviewees provided multiple examples of earlier outbreak detections but suggested notifications and logging could be improved to ensure action. EBS proved effective in detecting outbreaks, but we noted clear opportunities for efficiency gains. We recommend improving signal logging, standardizing processes, and revising outputs to ensure appropriate public health action.

Understanding patterns of adherence to COVID-19 mitigation measures: a qualitative interview study.

BACKGROUND: Evidence highlights the disproportionate impact of measures that have been introduced to reduce the spread of coronavirus on individuals from Black, Asian and minority ethnic (BAME) communities, and among those on a low income. An understanding of barriers to adherence in these populations is needed. In this qualitative study, we examined the patterns of adherence to mitigation measures and reasons underpinning these behaviors. METHODS: Semi-structured interviews were conducted with 20 participants from BAME and low-income White backgrounds. The topic guide was designed to explore how individuals are adhering to social distancing and self-isolation during the pandemic and to explore the reasons underpinning this behavior. RESULTS: We identified three categories of adherence to lockdown measures: (i) caution-motivated super-adherence (ii) risk-adapted partial-adherence and (iii) necessity-driven partial-adherence. Decisions about adherence considered potential for exposure to the virus, ability to reduce risk through use of protective measures and perceived importance of/need for the behavior. CONCLUSIONS: This research highlights a need for a more nuanced understanding of adherence to lockdown measures. Provision of practical and financial support could reduce the number of people who have to engage in necessity-driven partial-adherence. More evidence is required on population level risks of people adopting risk-adapted partial-adherence.

Engagement with daily testing instead of self-isolating in contacts of confirmed cases of SARS-CoV-2.

BACKGROUND: In December 2020, Public Health England with NHS Test and Trace initiated a pilot study in which close contacts of people with confirmed COVID-19 were given the option to carryout lateral flow device antigen tests at home, as an alternative to self-isolation for 10-14 days. In this study, we evaluated engagement with daily testing, and assessed levels of adherence to the rules relating to behaviour following positive or negative test results. METHODS: We conducted a service evaluation of the pilot study, examining survey responses from a subset of those who responded to an evaluation questionnaire. We used an online cross-sectional survey offered to adult contacts of confirmed COVID-19 cases who consented to daily testing. We used a comparison group of contacts who were not offered testing and instead self-isolated. RESULTS: Acceptability of daily testing was lower among survey respondents who were not offered the option of testing and among people from ethnic minority groups. Overall, 52% of respondents reported being more likely to share details of people that they had been in contact with following a positive test result, if they knew that their contacts would be offered the option of daily testing. Only 2% reported that they would be less likely to provide details of their contacts. On the days that they were trying to self-isolate, 19% of participants reported that they left the house, with no significant group differences. Following a negative test, 13% of respondents reported that they increased their contacts, but most (58%) reported having fewer risky contacts. CONCLUSIONS: Our data suggest that daily testing is potentially acceptable, may facilitate sharing contact details of close contacts among those who test positive for COVID-19, and promote adherence to self-isolation. A better understanding is needed of how to make this option more acceptable for all households. The impact of receiving a negative test on behaviour remains a risk that needs to be monitored and mitigated by appropriate messaging. Future research should examine attitudes and behaviour in a context where infection levels are lower, testing is more familiar, and restrictions on activity have been reduced.

Describing the indirect impact of COVID-19 on healthcare utilisation using syndromic surveillance systems.

BACKGROUND: Since the end of January 2020, the coronavirus (COVID-19) pandemic has been responsible for a global health crisis. In England a number of non-pharmaceutical interventions have been introduced throughout the pandemic, including guidelines on healthcare attendance (for example, promoting remote consultations), increased handwashing and social distancing. These interventions are likely to have impacted the incidence of non-COVID-19 conditions as well as healthcare seeking behaviour. Syndromic Surveillance Systems offer the ability to monitor trends in healthcare usage over time. METHODS: This study describes the indirect impact of COVID-19 on healthcare utilisation using a range of syndromic indicators including eye conditions, mumps, fractures, herpes zoster and cardiac conditions. Data from the syndromic surveillance systems monitored by Public Health England were used to describe the number of contacts with NHS 111, general practitioner (GP) In Hours (GPIH) and Out-of-Hours (GPOOH), Ambulance and Emergency Department (ED) services over comparable periods before and during the pandemic. RESULTS: The peak pandemic period in 2020 (weeks 13-20), compared to the same period in 2019, displayed on average a 12% increase in NHS 111 calls, an 11% decrease in GPOOH consultations, and a 49% decrease in ED attendances. In the GP In Hours system, conjunctivitis consultations decreased by 64% and mumps consultations by 31%. There was a 49% reduction in attendance at EDs for fractures, and there was no longer any weekend increase in ED fracture attendances, with similar attendance patterns observed across each day of the week. There was a decrease in the number of ED attendances with diagnoses of myocardial ischaemia. CONCLUSION: The COVID-19 pandemic drastically impacted healthcare utilisation for non-COVID-19 conditions, due to a combination of a probable decrease in incidence of certain conditions and changes in healthcare seeking behaviour. Syndromic surveillance has a valuable role in describing and understanding these trends.

Clinical diagnosis and treatment of common respiratory tract infections in relation to microbiological profiles in rural health facilities in China: implications for antibiotic stewardship.

BACKGROUND: This paper tries to describe prevalence and patterns of antibiotics prescription and bacteria detection and sensitivity to antibiotics in rural China and implications for future antibiotic stewardship. METHODS: The study was implemented in one village clinic and one township health center in each of four rural residential areas in Anhui Province, China. It used mixed-methods comprising non-participative observations, exit-survey and microbiological study. Observations were conducted to record clinical diagnosis and antibiotic prescription. Semi-structured questionnaire survey was used to collect patient's sociodemographic information and symptoms. Sputum and throat swabs were collected for bacterial culture and susceptibility testing. RESULTS: A total of 1068 (51.0% male vs 49.0% female) patients completed the study with diagnosis of respiratory tract infection (326,30.5%), bronchitis/tracheitis (249,23.3%), pharyngitis (119,11.1%) and others (374, 35.0%). They provided 683 sputum and 385 throat swab specimens. Antibiotics were prescribed for 88% of the RTI patients. Of all the specimens tested, 329 (31%) were isolated with bacteria. The most frequently detected bacteria were K. pneumonia (24% in all specimens), H. influenza (16%), H. parainfluenzae (15%), P. aeruginosa (6%), S.aureus (5%), M. catarrhalis (3%) and S. pneumoniae (2%). CONCLUSIONS: The study establishes the feasibility of conducting microbiological testing outside Tier 2 and 3 hospitals in rural China. It reveals that prescription of antibiotics, especially broad-spectrum and combined antibiotics, is still very common and there is a clear need for stewardship programs aimed at both reducing the number of prescriptions and promoting single and narrow-spectrum antibiotics.

Investigation into a national outbreak of STEC O157:H7 associated with frozen beef burgers, UK, 2017.

In November 2017, Public Health England identified an outbreak of Shiga toxin-producing Escherichia coli O157:H7 in England where whole genome sequencing results indicated cases were likely to be linked to a common source, and began investigations. Hypothesis generation included a review of enhanced surveillance data, a case-case study and trawling interviews. The hypothesis of interest was tested through the administration of focussed questionnaires and review of shopping history using loyalty card data. Twelve outbreak cases were detected, eight were hospitalised and four developed haemolytic uraemic syndrome. Frozen beef burgers supplied by a national retailer were identified as the vehicle of the outbreak. Testing of two left-over burger samples obtained from the freezers of two separate (unlinked) cases and a retained sample from the production premises were tested and found to be positive for the outbreak strain. A voluntary recall of the burgers was implemented by the retailer. Investigations at the production premises identified no contraventions of food safety legislation. Cooking guidance on the product packaging was deemed to be adequate and interviews with the cases/carers who prepared the burgers revealed no deficiencies in cooking practices at home. Given the long-shelf life of frozen burgers, the product recall likely prevented more cases.

The COVID-19 pandemic: a new challenge for syndromic surveillance.

The COVID-19 pandemic is exerting major pressures on society, health and social care services and science. Understanding the progression and current impact of the pandemic is fundamental to planning, management and mitigation of future impact on the population. Surveillance is the core function of any public health system, and a multi-component surveillance system for COVID-19 is essential to understand the burden across the different strata of any health system and the population. Many countries and public health bodies utilise 'syndromic surveillance' (using real-time, often non-specific symptom/preliminary diagnosis information collected during routine healthcare provision) to supplement public health surveillance programmes. The current COVID-19 pandemic has revealed a series of unprecedented challenges to syndromic surveillance including: the impact of media reporting during early stages of the pandemic; changes in healthcare-seeking behaviour resulting from government guidance on social distancing and accessing healthcare services; and changes in clinical coding and patient management systems. These have impacted on the presentation of syndromic outputs, with changes in denominators creating challenges for the interpretation of surveillance data. Monitoring changes in healthcare utilisation is key to interpreting COVID-19 surveillance data, which can then be used to better understand the impact of the pandemic on the population. Syndromic surveillance systems have had to adapt to encompass these changes, whilst also innovating by taking opportunities to work with data providers to establish new data feeds and develop new COVID-19 indicators. These developments are supporting the current public health response to COVID-19, and will also be instrumental in the continued and future fight against the disease.