Influenza epidemics observed in primary care from 1984 to 2017 in France: A decrease in epidemic size over time.
Adolescent
Adult
Aged
Child
Child, Preschool
Epidemics
/ statistics & numerical data
Female
France
/ epidemiology
Humans
Incidence
Infant
Infant, Newborn
Influenza, Human
/ epidemiology
Male
Middle Aged
Primary Health Care
/ statistics & numerical data
Sentinel Surveillance
Time Factors
Vaccination
/ statistics & numerical data
Vaccination Coverage
Young Adult
epidemics
influenza
influenza-like illness
primary care
surveillance
Journal
Influenza and other respiratory viruses
ISSN: 1750-2659
Titre abrégé: Influenza Other Respir Viruses
Pays: England
ID NLM: 101304007
Informations de publication
Date de publication:
03 2019
03 2019
Historique:
received:
13
03
2018
revised:
07
09
2018
accepted:
06
11
2018
pubmed:
15
11
2018
medline:
30
11
2019
entrez:
15
11
2018
Statut:
ppublish
Résumé
Epidemiological analysis of past influenza epidemics remains essential to understand the evolution of the disease and optimize control and prevention strategies. Here, we aimed to use data collected by a primary care surveillance system over the last three decades to study trends in influenza epidemics and describe epidemic profiles according to circulating influenza viruses. Influenza-like illness (ILI) weekly incidences were estimated using cases reported by general practitioners participating in the French Sentinelles network, between 1984 and 2017. Influenza epidemics were detected by applying a periodic regression to this time series. Epidemic (co-)dominant influenza virus (sub)types were determined using French virology data. During the study period, 297 607 ILI cases were reported allowing the detection of 33 influenza epidemics. On average, seasonal epidemics lasted 9 weeks and affected 4.1% of the population (95% CI 3.5; 4.7). Mean age of cases was 29 years. Epidemic size decreased over time by -66 cases per 100 000 population per season on average (95% CI -132; -0.2, P value = 0.049) and epidemic height decreased by -15 cases per 100 000 (95% CI -28; -2, P value = 0.022). Epidemic duration appeared stable over time. Epidemics were mostly dominated by A(H3N2) (n = 17, 52%), associated with larger epidemic size, higher epidemic peak and older age of cases. The declining trend in influenza epidemic size and height over the last 33 years might be related to several factors like increased vaccine coverage, hygiene improvements or changing in influenza viruses. However, further researches are needed to assess the impact of potential contributing factors to adapt influenza plans.
Sections du résumé
BACKGROUND
Epidemiological analysis of past influenza epidemics remains essential to understand the evolution of the disease and optimize control and prevention strategies. Here, we aimed to use data collected by a primary care surveillance system over the last three decades to study trends in influenza epidemics and describe epidemic profiles according to circulating influenza viruses.
METHODS
Influenza-like illness (ILI) weekly incidences were estimated using cases reported by general practitioners participating in the French Sentinelles network, between 1984 and 2017. Influenza epidemics were detected by applying a periodic regression to this time series. Epidemic (co-)dominant influenza virus (sub)types were determined using French virology data.
RESULTS
During the study period, 297 607 ILI cases were reported allowing the detection of 33 influenza epidemics. On average, seasonal epidemics lasted 9 weeks and affected 4.1% of the population (95% CI 3.5; 4.7). Mean age of cases was 29 years. Epidemic size decreased over time by -66 cases per 100 000 population per season on average (95% CI -132; -0.2, P value = 0.049) and epidemic height decreased by -15 cases per 100 000 (95% CI -28; -2, P value = 0.022). Epidemic duration appeared stable over time. Epidemics were mostly dominated by A(H3N2) (n = 17, 52%), associated with larger epidemic size, higher epidemic peak and older age of cases.
CONCLUSIONS
The declining trend in influenza epidemic size and height over the last 33 years might be related to several factors like increased vaccine coverage, hygiene improvements or changing in influenza viruses. However, further researches are needed to assess the impact of potential contributing factors to adapt influenza plans.
Identifiants
pubmed: 30428158
doi: 10.1111/irv.12620
pmc: PMC6379635
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
148-157Commentaires et corrections
Type : CommentIn
Informations de copyright
© 2018 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.
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