Nick Phin

The Early Transmission Dynamics of H1N1pdm Influenza in the United Kingdom.

We analyzed data on all laboratory-confirmed cases of H1N1pdm influenza in the UK to 10th June 2009 to estimate epidemiological characteristics. We estimated a mean incubation period of 2.05 days and serial interval of 2.5 days with infectivity peaking close to onset of symptoms. Transmission was initially sporadic but increased from mid-May in England and from early June in Scotland. We estimated 37% of transmission occurred in schools, 24% in households, 28% through travel abroad and the remainder in the wider community. Children under 16 were more susceptible to infection in the household (adjusted OR 5.80, 95% CI 2.99-11.82). Treatment with oseltamivir plus widespread use of prophylaxis significantly reduced transmission (estimated reduction 16%). Households not receiving oseltamivir within 3 days of symptom onset in the index case had significantly increased secondary attack rates (adjusted OR 3.42, 95% CI 1.51-8.55).

Pandemic (H1N1) 2009 influenza in the UK: clinical and epidemiological findings from the first few hundred (FF100) cases.

The UK was one of few European countries to document a substantial wave of pandemic (H1N1) 2009 influenza in summer 2009. The First Few Hundred (FF100) project ran from April-June 2009 gathering information on early laboratory-confirmed cases across the UK. In total, 392 confirmed cases were followed up. Children were predominantly affected (median age 15 years, IQR 10-27). Symptoms were mild and similar to seasonal influenza, with the exception of diarrhoea, which was reported by 27%. Eleven per cent of all cases had an underlying medical condition, similar to the general population. The majority (92%) were treated with antiviral drugs with 12% reporting adverse effects, mainly nausea and other gastrointestinal complaints. Duration of illness was significantly shorter when antivirals were given within 48 h of onset (median 5 vs. 9 days, P=0.01). No patients died, although 14 were hospitalized, of whom three required mechanical ventilation. The FF100 identified key clinical and epidemiological characteristics of infection with this novel virus in near real-time.

Increasing Pneumocystis Pneumonia, England, UK, 2000–2010

After an increase in the number of reported cases of Pneumocystis jirovecii pneumonia in England, we investigated data from 2000–2010 to verify the increase. We analyzed national databases for microbiological and clinical diagnoses of P. jirovecii pneumonia and associated deaths. We found that laboratory-confirmed cases in England had increased an average of 7% per year and that death certifications and hospital admissions also increased. Hospital admissions indicated increased P. jirovecii pneumonia diagnoses among patients not infected with HIV, particularly among those who had received a transplant or had a hematologic malignancy. A new risk was identified: preexisting lung disease. Infection rates among HIV-positive adults decreased. The results confirm that diagnoses of potentially preventable P. jirovecii pneumonia among persons outside the known risk group of persons with HIV infection have increased. This finding warrants further characterization of risk groups and a review of P. jirovecii pneumonia prevention strategies.

Personal protective equipment in an influenza pandemic: a UK simulation exercise

There is limited experience of both operational and financial impacts that adoption of UK pandemic influenza infection control guidance will have on the use of personal protective equipment (PPE), patients and staff. We attempted to assess these issues from a live exercise in a hospital in north-west England. During this 24h exercise, all staff on an acute general medical ward wore PPE and adopted the procedures described in the UK pandemic influenza infection control guidance. Teams of infection control nurses observed and recorded staff behaviour and practice throughout the exercise, including staff attitudes towards the use of PPE. Although World Health Organization recommendations on the likely use of high-level PPE (FFP3 respirators) proved to be excessive, more gloves and surgical masks were used than expected. Despite pre-exercise training, many staff lacked confidence in using PPE and following infection control measures. They found PPE uncomfortable, with even basic tasks taking longer than usual. Large quantities of clinical waste were generated: an additional 12 bags (570 L) per day. The estimates of PPE usage within this exercise challenge assumptions that large amounts of high-level PPE are required, with significant implications for healthcare budgets. A programme of ongoing infection control education is needed. Healthcare in a pandemic situation is not simply a case of applying pandemic influenza infection control guidance to current practice; hospitals need to consider changing the way care and services are delivered.

Use of Antiviral Drugs to Reduce Household Transmission of Pandemic (H1N1) 2009, United Kingdom

The United Kingdom implemented a containment strategy for pandemic (H1N1) 2009 through administering antiviral agents (AVs) to patients and their close contacts. This observational household cohort study describes the effect of AVs on household transmission. We followed 285 confirmed primary cases in 259 households with 761 contacts. At 2 weeks, the confirmed secondary attack rate (SAR) was 8.1% (62/761) and significantly higher in persons <16 years of age than in those >50 years of age (18.9% vs. 1.2%, p<0.001). Early (<48 hours) treatment of primary case-patients reduced SAR (4.5% vs. 10.6%, p = 0.003). The SAR in child contacts was 33.3% (10/30) when the primary contact was a woman and 2.9% (1/34) when the primary contact was a man (p = 0.010). Of 53 confirmed secondary case-patients, 45 had not received AV prophylaxis. The effectiveness of AV prophylaxis in preventing infection was 92%.

Oseltamivir-Resistant Pandemic (H1N1) 2009 Virus Infection in England and Scotland, 2009–2010

Monitoring of antiviral resistance is strongly recommended for immunocompromised patients.

Could influenza transmission be reduced by restricting mass gatherings? Towards an evidence-based policy framework

Abstract Introduction Mass gatherings (MG) may provide ideal conditions for influenza transmission. The evidence for an association between MG and influenza transmission is reviewed to assess whether restricting MG may reduce transmission. Methods Major databases were searched (Pubmed, EMBASE, Scopus, CINAHL), producing 1706 articles that were sifted by title, abstract, and full-text. A narrative approach was adopted for data synthesis. Results Twenty-four papers met the inclusion criteria, covering MG of varying sizes and settings, and including 9 observational studies, 10 outbreak reports, 4 event reports, and a quasi-experimental study. There is some evidence that certain types of MG may be associated with increased risk of influenza transmission. MG may also “seed” new strains into an area, and may instigate community transmission in a pandemic. Restricting MGs, in combination with other social distancing interventions, may help reduce transmission, but it was not possible to identify conclusive evidence on the individual effect of MG restriction alone. Evidence suggests that event duration and crowdedness may be the key factors that determine the risk of influenza transmission, and possibly the type of venue (indoor/outdoor). Conclusion These factors potentially represent a basis for a policy-making framework for MG restrictions in the event of a severe pandemic.

Minimum dataset for confirmed human cases of influenza H5N1

Sheila Bird and Jeremy Farrar’s Comment (Aug 30, p 696) raises important issues that the Health Protection Agency and the UK devolved administrations have worked on for some time: the timely, consistent collection of detailed clinical and epidemiological data on cases of avian and pandemic infl uenza and their contacts. The output, the UK Avian Infl uenza Management System (AIMS), is a password-protected, web-based software package designed to collate epidemio logical, clinical, and personal data on human cases of avian in fl uenza (particularly, although not ex clusively, H5N1) and in the event of a pan demic, on the fi rst few hundred pandemic infl uenza cases in the UK. The minimum dataset has relied heavily on the multidisciplinary input of public-health professionals, infectiousdisease modellers, and clinicians. The system design allows data on cases to be entered in real time until discharge or death (fi gure). Data extracts are available as predetermined reports or fl at fi les for detailed statistical analysis. However, a database on its own is in suffi cient; for consistency and comparability, protocols—agreed and test ed before hand—are necessary for im portant issues such as case defi nitions, identifi cation and follow-up of con tacts, what happens to contacts who become cases, and the testing of cases and contacts. The European Centre for Disease Prevention and Control (ECDC) has suggested that individual countries should populate WHO/ECDC international databases with H5N1 cases. The UK is well placed to provide the international community with data for any internationally agreed minimum dataset. We look forward to continuing dialogue with ECDC and hope that other countries consider our system when designing their own.

Resource Allocation during an Influenza Pandemic

We are grateful to Phin and Davies for providing an update on the pandemic flu planning situation in the United Kingdom (1) after publication of our letter (2). We agree with their emphasis that pandemic planning in the United Kindgom is in many regards well developed in comparison with other countries. Many of the updates that they describe provide useful contributions but the final version of UK ethical guidance is more a general statement of principles than a practical guide. Unfortunately, it has pulled back from some of the more definite statements in the earlier consultation documents available at the time of our letter. An important need for practical guidance for frontline and managerial staff on the ethical aspects of pandemic response remains as a gap in the United Kingdom and elsewhere. For critical care, a useful recent contribution is the report produced by the Task Force on Mass Critical Care, especially the framework for allocation of scarce resources in mass critical care (3). The shift away from pandemic influenza–specific criteria to a more generic framework for resource allocation that can compare patients with pandemic influenza and those with other usual noninfluenza conditions is welcome. Similar practical approaches outside the critical care area are important priorities for work in pandemic preparedness. In addition, systems must be in place for rapid modification and communication of the criteria for referral and admission, taking into account the severity of the pandemic and availability of healthcare resources. Healthcare services must not only be transparent and fair in this process, they must also be seen by the public as being so. Engagement with the public on values and principles underlying resource allocation would be of paramount importance during a pandemic.