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1.
Epidemiol Infect ; 144(11): 2295-305, 2016 08.
Artículo en Inglés | MEDLINE | ID: mdl-27350234

RESUMEN

We studied the spread of influenza in the community between 1993 and 2009 using primary-care surveillance data to investigate if the onset of influenza was age-related. Virus detections [A(H3N2), B, A(H1N1)] and clinical incidence of influenza-like illness (ILI) in 12·3 million person-years in the long-running Royal College of General Practitioners-linked clinical-virological surveillance programme in England & Wales were examined. The number of days between symptom onset and the all-age peak ILI incidence were compared by age group for each influenza type/subtype. We found that virus detection and ILI incidence increase, peak and decrease were in unison. The mean interval between symptom onset to peak ILI incidence in virus detections (all ages) was: A(H3N2) 20·5 [95% confidence interval (CI) 19·7-21·6] days; B, 18·8 (95% CI 15·8·0-21·7) days; and A(H1N1) 17·0 (95% CI 15·6-18·4) days. Differences by age group were examined using the Kruskal-Wallis test. For A(H3N2) and A(H1N1) viruses the interval was similar in each age group. For influenza B there were highly significant differences by age group (P = 0·0001). Clinical incidence rates of ILI reported in the 8 weeks preceding the period of influenza virus activity were used to estimate a baseline incidence and threshold value (upper 95% CI of estimate) which was used as a marker of epidemic progress. Differences between the age groups in the week in which the threshold was reached were small and not localized to any age group. In conclusion we found no evidence to suggest that influenza A(H3N2) and A(H1N1) occurs in the community in one age group before another. For influenza B, virus detection was earlier in children aged 5-14 years than in persons aged ⩾25 years.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/fisiología , Subtipo H3N2 del Virus de la Influenza A/fisiología , Virus de la Influenza B/fisiología , Gripe Humana/epidemiología , Adolescente , Adulto , Factores de Edad , Anciano , Niño , Preescolar , Inglaterra/epidemiología , Femenino , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Vigilancia de la Población , Gales/epidemiología , Adulto Joven
2.
Epidemiol Infect ; 144(11): 2251-9, 2016 08.
Artículo en Inglés | MEDLINE | ID: mdl-27068133

RESUMEN

Climate change experts predict the number of nuisance-biting arthropods in England will increase but there is currently no known surveillance system in place to monitor or assess the public health impact of arthropod bites. This retrospective ecological study utilized arthropod bites requiring healthcare from five national real-time syndromic surveillance systems monitoring general practitioner (GP) consultations (in-hours and out-of-hours), emergency department (ED) attendances and telephone calls to remote advice services to determine baseline incidence in England between 2000 and 2013 and to assess the association between arthropod bites and temperature. During summer months (weeks 20-40) we estimated that arthropod bites contribute a weekly median of ~4000 GP consultations, 750 calls to remote advice services, 700 ED and 1300 GP out-of-hours attendances. In all systems, incidence was highest during summer months compared to the rest of the year. Arthropod bites were positively associated with temperature with incidence rate ratios (IRRs) that ranged between systems from 1·03 [95% confidence interval (CI) 1·01-1·06] to 1·14 (95% CI 1·11-1·16). Using syndromic surveillance systems we have established and described baseline incidence of arthropod bites and this can now be monitored routinely in real time to assess the impact of extreme weather events and climate change.


Asunto(s)
Servicios Médicos de Urgencia/estadística & datos numéricos , Mordeduras y Picaduras de Insectos/epidemiología , Salud Pública , Mordeduras de Garrapatas/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Animales , Niño , Preescolar , Cambio Climático , Inglaterra/epidemiología , Femenino , Humanos , Incidencia , Lactante , Recién Nacido , Mordeduras y Picaduras de Insectos/etiología , Masculino , Persona de Mediana Edad , Vigilancia de la Población , Estudios Retrospectivos , Temperatura , Mordeduras de Garrapatas/etiología , Adulto Joven
3.
Euro Surveill ; 20(10): 21058, 2015 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-25788252

RESUMEN

This report aims to evaluate the usefulness of self-sampling as an approach for future national surveillance of emerging respiratory infections by comparing virological data from two parallel surveillance schemes in England. Nasal swabs were obtained via self-administered sampling from consenting adults (≥ 16 years-old) with influenza symptoms who had contacted the National Pandemic Flu Service (NPFS) health line during the 2009 influenza pandemic. Equivalent samples submitted by sentinel general practitioners participating in the national influenza surveillance scheme run jointly by the Royal College of General Practitioners (RCGP) and Health Protection Agency were also obtained. When comparable samples were analysed there was no significant difference in results obtained from self-sampling and clinician-led sampling schemes. These results demonstrate that self-sampling can be applied in a responsive and flexible manner, to supplement sentinel clinician-based sampling, to achieve a wide spread and geographically representative way of assessing community transmission of a known organism.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Gripe Humana/virología , Autoadministración/métodos , Vigilancia de Guardia , Manejo de Especímenes/métodos , Adulto , Inglaterra/epidemiología , Femenino , Humanos , Gripe Humana/diagnóstico , Gripe Humana/epidemiología , Masculino , Cavidad Nasal/virología , Pandemias , ARN Viral/genética , Características de la Residencia , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Encuestas y Cuestionarios
4.
J Public Health (Oxf) ; 37(2): 295-304, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25096307

RESUMEN

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.


Asunto(s)
Antivirales/uso terapéutico , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Brotes de Enfermedades , Inglaterra/epidemiología , Femenino , Humanos , Masculino , Vigilancia de la Población , Salud Pública
5.
Epidemiol Infect ; 143(1): 1-12, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25023603

RESUMEN

General Practitioner consultation rates for influenza-like illness (ILI) are monitored through several geographically distinct schemes in the UK, providing early warning to government and health services of community circulation and intensity of activity each winter. Following on from the 2009 pandemic, there has been a harmonization initiative to allow comparison across the distinct existing surveillance schemes each season. The moving epidemic method (MEM), proposed by the European Centre for Disease Prevention and Control for standardizing reporting of ILI rates, was piloted in 2011/12 and 2012/13 along with the previously proposed UK method of empirical percentiles. The MEM resulted in thresholds that were lower than traditional thresholds but more appropriate as indicators of the start of influenza virus circulation. The intensity of the influenza season assessed with the MEM was similar to that reported through the percentile approach. The MEM pre-epidemic threshold has now been adopted for reporting by each country of the UK. Further work will continue to assess intensity of activity and apply standardized methods to other influenza-related data sources.


Asunto(s)
Notificación de Enfermedades/métodos , Monitoreo Epidemiológico , Gripe Humana/diagnóstico , Gripe Humana/epidemiología , Atención Primaria de Salud/métodos , Humanos , Reino Unido/epidemiología
6.
Euro Surveill ; 19(27): 5-13, 2014 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-25033051

RESUMEN

The effectiveness of the 2012/13 trivalent seasonal influenza vaccine (TIV) was assessed using a test-negative case-control study of patients consulting primary care with influenza-like illness in the United Kingdom. Strain characterisation was undertaken on selected isolates. Vaccine effectiveness (VE) against confirmed influenza A(H3N2), A(H1N1) and B virus infection, adjusted for age, sex, surveillance scheme (i.e. setting) and month of sample collection was 26% (95% confidence interval (CI): -4 to 48), 73% (95% CI: 37 to 89) and 51% (95% CI: 34 to 63) respectively. There was an indication, although not significant, that VE declined by time since vaccination for influenza A(H3N2) (VE 50% within three months, 2% after three months, p=0.25). For influenza A(H3N2) this is the second season of low VE, contributing to the World Health Organization (WHO) recommendation that the 2013/14 influenza vaccine strain composition be changed to an A(H3N2) virus antigenically like cell-propagated prototype 2012/13 vaccine strain (A/Victoria/361/2011). The lower VE seen for type B is consistent with antigenic drift away from the 2012/13 vaccine strain. The majority of influenza B viruses analysed belong to the genetic clade 2 and were antigenically distinguishable from the 2012/13 vaccine virus B/Wisconsin/1/2010 clade 3. These findings supported the change to the WHO recommended influenza B vaccine component for 2013/14.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/inmunología , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Vigilancia de Guardia , Adolescente , Adulto , Anciano , Estudios de Casos y Controles , Niño , Femenino , Pruebas de Inhibición de Hemaglutinación , Humanos , Subtipo H1N1 del Virus de la Influenza A/clasificación , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/inmunología , Subtipo H3N2 del Virus de la Influenza A/clasificación , Subtipo H3N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/inmunología , Virus de la Influenza B/genética , Virus de la Influenza B/aislamiento & purificación , Vacunas contra la Influenza/inmunología , Vacunas contra la Influenza/uso terapéutico , Gripe Humana/inmunología , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Atención Primaria de Salud , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estaciones del Año , Análisis de Secuencia de ADN , Factores de Tiempo , Resultado del Tratamiento , Reino Unido/epidemiología , Vacunación/estadística & datos numéricos
7.
Euro Surveill ; 19(22)2014 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-24925457

RESUMEN

As part of the introduction and roll-out of a universal childhood live-attenuated influenza vaccination programme, 4­11 year-olds were vaccinated in seven pilot areas in England in the 2013/14 influenza season. This paper presents the uptake and impact of the programme for a range of disease indicators. End-of-season uptake was defined as the number of children in the target population who received at least one dose of influenza vaccine. Between week 40 2013 and week 15 2014, cumulative disease incidence per 100,000 population (general practitioner consultations for influenza-like illness and laboratory-confirmed influenza hospitalisations), cumulative influenza swab positivity in primary and secondary care and cumulative proportion of emergency department respiratory attendances were calculated. Indicators were compared overall and by age group between pilot and non-pilot areas. Direct impact was defined as reduction in cumulative incidence based on residence in pilot relative to non-pilot areas in 4­11 year-olds. Indirect impact was reduction between pilot and non-pilot areas in <4 year-olds and >11 year-olds. Overall vaccine uptake of 52.5% (104,792/199,475) was achieved. Although influenza activity was low, a consistent, though not statistically significant, decrease in cumulative disease incidence and influenza positivity across different indicators was seen in pilot relative to non-pilot areas in both targeted and non-targeted age groups, except in older age groups, where no difference was observed for secondary care indicators.


Asunto(s)
Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Vacunación/estadística & datos numéricos , Vacunas Atenuadas/administración & dosificación , Niño , Preescolar , Inglaterra/epidemiología , Femenino , Humanos , Programas de Inmunización/estadística & datos numéricos , Incidencia , Vacunas contra la Influenza/efectos adversos , Gripe Humana/epidemiología , Masculino , Proyectos Piloto , Instituciones Académicas , Estaciones del Año , Vacunas Atenuadas/efectos adversos
8.
Euro Surveill ; 18(5)2013 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-23399421

RESUMEN

The early experience of the United Kingdom (UK) is that influenza B has dominated the influenza 2012/13 season. Overall trivalent influenza vaccine (TIV) adjusted vaccine effectiveness (VE) against all laboratory-confirmed influenza in primary care was 51% (95% confidence interval (CI): 27% to 68%); TIV adjusted VE against influenza A alone or influenza B alone was 49% (95% CI: -2% to 75%) and 52% (95% CI: 23% to 70%) respectively. Vaccination remains the best protection against influenza.


Asunto(s)
Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/aislamiento & purificación , Vacunas contra la Influenza/administración & dosificación , Gripe Humana/prevención & control , Estaciones del Año , Adolescente , Adulto , Distribución por Edad , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Virus de la Influenza A/genética , Virus de la Influenza A/inmunología , Virus de la Influenza B/genética , Virus de la Influenza B/inmunología , Vacunas contra la Influenza/inmunología , Gripe Humana/diagnóstico , Gripe Humana/epidemiología , Gripe Humana/virología , Modelos Logísticos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Atención Primaria de Salud , Reacción en Cadena en Tiempo Real de la Polimerasa , Vigilancia de Guardia , Encuestas y Cuestionarios , Resultado del Tratamiento , Reino Unido/epidemiología , Vacunación/estadística & datos numéricos , Adulto Joven
9.
Euro Surveill ; 18(5)2013 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-23399424

RESUMEN

The 2011/12 season was characterised by unusually late influenza A (H3N2) activity in the United Kingdom (UK). We measured vaccine effectiveness (VE) of the 2011/12 trivalent seasonal influenza vaccine (TIV) in a test-negative case­control study in primary care. Overall VE against confirmed influenza A (H3N2) infection, adjusted for age, surveillance scheme and month, was 23% (95% confidence interval (CI): -10 to 47). Stratified analysis by time period gave an adjusted VE of 43% (95% CI: -34 to 75) for October 2011 to January 2012 and 17% (95% CI: -24 to 45) for February 2012 to April 2012. Stratified analysis by time since vaccination gave an adjusted VE of 53% (95% CI: 0 to 78) for those vaccinated less than three months, and 12% (95% CI: -31 to 41) for those vaccinated three months or more before onset of symptoms (test for trend: p=0.02). For confirmed influenza B infection, adjusted VE was 92% (95% CI: 38 to 99). A proportion (20.6%) of UK influenza A(H3N2) viruses circulating in 2011/12 showed reduced reactivity (fourfold difference in haemagglutination inhibition assays) to the A/Perth/16/2009 2011/12 vaccine component, with no significant change in proportion over the season. Overall TIV protection against influenza A(H3N2) infection was low, with significant intraseasonal waning.


Asunto(s)
Vacunas contra la Influenza/administración & dosificación , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Adolescente , Adulto , Anciano , Estudios de Casos y Controles , Niño , Intervalos de Confianza , Femenino , Pruebas de Inhibición de Hemaglutinación , Humanos , Subtipo H3N2 del Virus de la Influenza A/genética , Subtipo H3N2 del Virus de la Influenza A/inmunología , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Vacunas contra la Influenza/inmunología , Gripe Humana/diagnóstico , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Atención Primaria de Salud , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estaciones del Año , Vigilancia de Guardia , Análisis de Secuencia de ADN , Factores de Tiempo , Resultado del Tratamiento , Reino Unido/epidemiología , Vacunación/estadística & datos numéricos
10.
Epidemiol Infect ; 141(3): 620-30, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22691710

RESUMEN

An analysis was undertaken to measure age-specific vaccine effectiveness (VE) of 2010/11 trivalent seasonal influenza vaccine (TIV) and monovalent 2009 pandemic influenza vaccine (PIV) administered in 2009/2010. The test-negative case-control study design was employed based on patients consulting primary care. Overall TIV effectiveness, adjusted for age and month, against confirmed influenza A(H1N1)pdm 2009 infection was 56% (95% CI 42-66); age-specific adjusted VE was 87% (95% CI 45-97) in <5-year-olds and 84% (95% CI 27-97) in 5- to 14-year-olds. Adjusted VE for PIV was only 28% (95% CI -6 to 51) overall and 72% (95% CI 15-91) in <5-year-olds. For confirmed influenza B infection, TIV effectiveness was 57% (95% CI 42-68) and in 5- to 14-year-olds 75% (95% CI 32-91). TIV provided moderate protection against the main circulating strains in 2010/2011, with higher protection in children. PIV administered during the previous season provided residual protection after 1 year, particularly in the <5 years age group.


Asunto(s)
Subtipo H1N1 del Virus de la Influenza A , Virus de la Influenza B , Vacunas contra la Influenza , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Adolescente , Adulto , Factores de Edad , Anciano , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Humanos , Gripe Humana/virología , Masculino , Persona de Mediana Edad , Pandemias , Reino Unido/epidemiología , Adulto Joven
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