Percentage reduction in all respiratory outcomes associated with targeted vaccination of 2- and 3- year-old children.

<p>Percentage reduction in all respiratory outcomes associated with targeted vaccination of 2- and 3- year-old children.</p

Impact of increased influenza vaccination in 2–3-year-old children on disease burden within the general population: A Bayesian model-based approach

<div><p>Introduction</p><p>During the 2013–2014 influenza season, Public Health England extended routine influenza vaccination to all 2- and 3-year-old children in England. To estimate the impact of this change in policy on influenza-related morbidity and mortality, we developed a disease transmission and surveillance model informed by real-world data.</p><p>Methods</p><p>We combined real-world and literature data sources to construct a model of influenza transmission and surveillance in England. Data were obtained for four influenza seasons, starting with the 2010–2011 season. Bayesian inference was used to estimate model parameters on a season-by-season basis to assess the impact of targeting 2- and 3-year-old children for influenza vaccination. This provided the basis for the construction of counterfactual scenarios comparing vaccination rates of ~2% and ~35% in the 2- and 3- year-old population to estimate reductions in general practitioner (GP) influenza-like-illness (ILI) consultations, respiratory hospitalizations and deaths in the overall population.</p><p>Results</p><p>Our model was able to replicate the main patterns of influenza across the four seasons as observed through laboratory surveillance data. Targeting 2- and 3-year-old children for influenza vaccination resulted in reductions in the general population of between 6.2–9.9% in influenza-attributable GP ILI consultations, 6.1–10.7% in influenza-attributable respiratory hospitalizations, and 5.7–9.4% in influenza-attributable deaths. The decrease in influenza-attributable ILI consultations represents a reduction of between 4.5% and 7.3% across all ILI consultations. The reduction in influenza-attributable respiratory hospitalizations represents a reduction of between 1.2% and 2.3% across all respiratory hospitalizations. Reductions in influenza-attributable respiratory deaths represent a reduction of between 0.9% and 2.4% in overall respiratory deaths.</p><p>Conclusion</p><p>This study has provided evidence that extending routine influenza vaccination to all healthy children aged 2 and 3 years old leads to benefits in terms of reduced utilization of healthcare resources and fewer respiratory health outcomes and deaths.</p></div

Model-estimated number of weekly respiratory hospitalizations (grey line) vs observed number of weekly respiratory hospitalizations (blue line).

<p>Model-estimated number of weekly respiratory hospitalizations (grey line) vs observed number of weekly respiratory hospitalizations (blue line).</p

Reductions in influenza-attributable burden associated with targeted vaccination of 2- and 3-year-old children.

<p>Reductions in influenza-attributable burden associated with targeted vaccination of 2- and 3-year-old children.</p

Influenza-attributable burden for influenza-like-illness (ILI) general practitioner (GP) consultations, respiratory hospitalizations, and respiratory deaths.

<p>Influenza-attributable burden for influenza-like-illness (ILI) general practitioner (GP) consultations, respiratory hospitalizations, and respiratory deaths.</p

Matrix of age-specific contacts as derived from the POLYMOD study.

<p>Matrix of age-specific contacts as derived from the POLYMOD study.</p

Comparison of rates of influenza infection and influenza-attributable burden between observed (Scenario 1) and modelled (Scenario 2) values.

<p>Horizontal bar is the median, with shaded bar (“hinges”) representing 25th and 75th percentiles. Vertical bar spans values within 1.5 times inter-quantile range from hinges. In seasons 2010–2013 the modelled rates are with targeted vaccination. In 2013–2014 lack of targeted vaccination is the model.</p

Strain-specific weekly infections for each season, by age group.

<p>Strain-specific weekly infections for each season, by age group.</p

Estimated percentage reduction in infection rate as a result of targeted vaccination of all 2- and 3-year-old children.

<p>Estimated percentage reduction in infection rate as a result of targeted vaccination of all 2- and 3-year-old children.</p

Surveillance pyramid of influenza: A schematic breakdown of influenza-infected population into groups.

<p>CPRD: Clinical Practice Research Datalink; RCGP: Royal College of General Practitioners.</p