tetano
Editor, Senior Moderator
Influenza Other Respi Viruses. 2012 Jun 14. doi: 10.1111/j.1750-2659.2012.00388.x. [Epub ahead of print]
Understanding the dynamics of seasonal influenza in Italy: incidence, transmissibility and population susceptibility in a 9-year period.
Lunelli A, Rizzo C, Puzelli S, Bella A, Montomoli E, Rota MC, Donatelli I, Pugliese A.
Source
Department of Mathematics, University of Trento, Trento, Italy National Centre for Epidemiology, Surveillance and Health Promotion, National Institute of Health, Siena, Italy Department of Infectious, Parasitic and Immune-mediated Diseases, National Institute of Health, Rome, Italy Department of Physiopathology, Experimental Medicine and Public Health, University of Siena, Siena, Italy.
Abstract
Please cite this paper as: Lunelli et al. (2012) Understanding the dynamics of seasonal influenza in Italy: incidence, transmissibility and population susceptibility in a 9-year period. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750-2659.2012.00388.x. Objectives: Influenza surveillance systems have been established in many countries in the world, yielding timely information about the intensity and features of seasonal outbreaks. Such data have also been used to estimate epidemiological parameters and to evaluate the effect of factors on infection dynamics. However, little is known about the extent of under-reporting in surveillance data, and thus of the true influenza incidence in the population. Design: Through mathematical and statistical modelling, we analysed Italian epidemiological and virological surveillance data collected together with serological data derived from influenza vaccine clinical trials performed in Italy. Results: Depending on the season, the reporting rate estimates ranged between 20% and 33% of the total incidence with higher reporting rates in seasons dominated by A/H3N2 virus. Despite a generally higher number of individuals immune against A/H3N2 viruses, effective reproduction ratios were quite similar in all seasons varying between 1?2 and 1?4. We observed an age-dependent transmissibility for different subtypes: susceptible children were more likely than susceptible adults and elderly to get infected when A/H1N1 or B strains were circulating, while no clear age-dependence was found for A/H3N2. We also perform sensitivity analysis under different assumptions for vaccine effectiveness, generation time (GT) and model variants; we found that the overall results in predicted patterns were extremely similar, with a slightly better fit obtained with shorter GTs. Conclusions: Our results provide relevant information on the influenza dynamics to fine-tune intervention strategies and for data collection improvement.
? 2012 Blackwell Publishing Ltd.
PMID:
22694182
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/22694182
Understanding the dynamics of seasonal influenza in Italy: incidence, transmissibility and population susceptibility in a 9-year period.
Lunelli A, Rizzo C, Puzelli S, Bella A, Montomoli E, Rota MC, Donatelli I, Pugliese A.
Source
Department of Mathematics, University of Trento, Trento, Italy National Centre for Epidemiology, Surveillance and Health Promotion, National Institute of Health, Siena, Italy Department of Infectious, Parasitic and Immune-mediated Diseases, National Institute of Health, Rome, Italy Department of Physiopathology, Experimental Medicine and Public Health, University of Siena, Siena, Italy.
Abstract
Please cite this paper as: Lunelli et al. (2012) Understanding the dynamics of seasonal influenza in Italy: incidence, transmissibility and population susceptibility in a 9-year period. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750-2659.2012.00388.x. Objectives: Influenza surveillance systems have been established in many countries in the world, yielding timely information about the intensity and features of seasonal outbreaks. Such data have also been used to estimate epidemiological parameters and to evaluate the effect of factors on infection dynamics. However, little is known about the extent of under-reporting in surveillance data, and thus of the true influenza incidence in the population. Design: Through mathematical and statistical modelling, we analysed Italian epidemiological and virological surveillance data collected together with serological data derived from influenza vaccine clinical trials performed in Italy. Results: Depending on the season, the reporting rate estimates ranged between 20% and 33% of the total incidence with higher reporting rates in seasons dominated by A/H3N2 virus. Despite a generally higher number of individuals immune against A/H3N2 viruses, effective reproduction ratios were quite similar in all seasons varying between 1?2 and 1?4. We observed an age-dependent transmissibility for different subtypes: susceptible children were more likely than susceptible adults and elderly to get infected when A/H1N1 or B strains were circulating, while no clear age-dependence was found for A/H3N2. We also perform sensitivity analysis under different assumptions for vaccine effectiveness, generation time (GT) and model variants; we found that the overall results in predicted patterns were extremely similar, with a slightly better fit obtained with shorter GTs. Conclusions: Our results provide relevant information on the influenza dynamics to fine-tune intervention strategies and for data collection improvement.
? 2012 Blackwell Publishing Ltd.
PMID:
22694182
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/22694182