tetano
Editor, Senior Moderator
PLoS One. 2016 Mar 24;11(3):e0151575. doi: 10.1371/journal.pone.0151575. eCollection 2016.
[h=1]Twin Peaks: A/H1N1 Pandemic Influenza Virus Infection and Vaccination in Norway, 2009-2010.[/h] Van Effelterre T[SUP]1[/SUP], Dos Santos G[SUP]2[/SUP], Shinde V[SUP]3[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] Vaccination campaigns against A/H1N1 2009 pandemic influenza virus (A/H1N1p) began in autumn 2009 in Europe, after the declaration of the pandemic at a global level. This study aimed to estimate the proportion of individuals vaccinated against A/H1N1p in Norway who were already infected (asymptomatically or symptomatically) by A/H1N1p before vaccination, using a mathematical model.
[h=4]METHODS:[/h] A dynamic, mechanistic, mathematical model of A/H1N1p transmission was developed for the Norwegian population. The model parameters were estimated by calibrating the model-projected number of symptomatic A/H1N1p cases to the number of laboratory-confirmed A/H1N1p cases reported to the surveillance system, accounting for potential under-reporting. It was assumed in the base case that the likelihood of vaccination was independent of infection/disease state. A sensitivity analysis explored the effects of four scenarios in which current or previous symptomatic A/H1N1p infection would influence the likelihood of being vaccinated.
[h=4]RESULTS:[/h] The number of model-projected symptomatic A/H1N1p cases by week during the epidemic, accounting for under-reporting and timing, closely matched that of the laboratory-confirmed A/H1N1p cases reported to the surveillance system. The model-projected incidence of symptomatic A/H1N1p infection was 27% overall, 55% in people <10 years old and 41% in people 10-20 years old. The model-projected percentage of individuals vaccinated against A/H1N1p who were already infected with A/H1N1p before being vaccinated was 56% overall, 62% in people <10 years old and 66% in people 10-20 years old. The results were sensitive to assumptions about the independence of vaccination and infection; however, even when current or previous symptomatic A/H1N1p infection was assumed to reduce the likelihood of vaccination, the estimated percentage of individuals who were infected before vaccination remained at least 32% in all age groups.
[h=4]CONCLUSION:[/h] This analysis suggests that over half the people vaccinated against A/H1N1p in Norway during the 2009 pandemic may already have been infected by A/H1N1p before being vaccinated.
PMID: 27010830 [PubMed - in process] Free full text
[h=1]Twin Peaks: A/H1N1 Pandemic Influenza Virus Infection and Vaccination in Norway, 2009-2010.[/h] Van Effelterre T[SUP]1[/SUP], Dos Santos G[SUP]2[/SUP], Shinde V[SUP]3[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] Vaccination campaigns against A/H1N1 2009 pandemic influenza virus (A/H1N1p) began in autumn 2009 in Europe, after the declaration of the pandemic at a global level. This study aimed to estimate the proportion of individuals vaccinated against A/H1N1p in Norway who were already infected (asymptomatically or symptomatically) by A/H1N1p before vaccination, using a mathematical model.
[h=4]METHODS:[/h] A dynamic, mechanistic, mathematical model of A/H1N1p transmission was developed for the Norwegian population. The model parameters were estimated by calibrating the model-projected number of symptomatic A/H1N1p cases to the number of laboratory-confirmed A/H1N1p cases reported to the surveillance system, accounting for potential under-reporting. It was assumed in the base case that the likelihood of vaccination was independent of infection/disease state. A sensitivity analysis explored the effects of four scenarios in which current or previous symptomatic A/H1N1p infection would influence the likelihood of being vaccinated.
[h=4]RESULTS:[/h] The number of model-projected symptomatic A/H1N1p cases by week during the epidemic, accounting for under-reporting and timing, closely matched that of the laboratory-confirmed A/H1N1p cases reported to the surveillance system. The model-projected incidence of symptomatic A/H1N1p infection was 27% overall, 55% in people <10 years old and 41% in people 10-20 years old. The model-projected percentage of individuals vaccinated against A/H1N1p who were already infected with A/H1N1p before being vaccinated was 56% overall, 62% in people <10 years old and 66% in people 10-20 years old. The results were sensitive to assumptions about the independence of vaccination and infection; however, even when current or previous symptomatic A/H1N1p infection was assumed to reduce the likelihood of vaccination, the estimated percentage of individuals who were infected before vaccination remained at least 32% in all age groups.
[h=4]CONCLUSION:[/h] This analysis suggests that over half the people vaccinated against A/H1N1p in Norway during the 2009 pandemic may already have been infected by A/H1N1p before being vaccinated.
PMID: 27010830 [PubMed - in process] Free full text