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Age-specific incidence of A/H1N1 2009 influenza infection in England from sequential antibody prevalence data using likelihood-based estimation.

Baguelin M, Hoschler K, Stanford E, Waight P, Hardelid P, Andrews N, Miller E - PLoS ONE (2011)

Bottom Line: This method is applied to derive the cumulative and weekly incidence of A/H1N1 pandemic influenza in England during the second wave using sera taken between September 2009 and February 2010 in four age groups (1-4, 5-14, 15-24, 25-44 years).The highest cumulative incidence was in 5-14 year olds (59%, 95% credible interval (CI): 52%, 68%) followed by 1-4 year olds (49%, 95% CI: 38%, 61%), rates 20 and 40 times higher respectively than estimated from clinical surveillance.The method provides a more accurate and continuous measure of incidence than achieved by comparing prevalence in samples grouped by time period.

View Article: PubMed Central - PubMed

Affiliation: Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency, London, United Kingdom. marc.baguelin@hpa.org.uk

ABSTRACT
Estimating the age-specific incidence of an emerging pathogen is essential for understanding its severity and transmission dynamics. This paper describes a statistical method that uses likelihoods to estimate incidence from sequential serological data. The method requires information on seroconversion intervals and allows integration of information on the temporal distribution of cases from clinical surveillance. Among a family of candidate incidences, a likelihood function is derived by reconstructing the change in seroprevalence from seroconversion following infection and comparing it with the observed sequence of positivity among the samples. This method is applied to derive the cumulative and weekly incidence of A/H1N1 pandemic influenza in England during the second wave using sera taken between September 2009 and February 2010 in four age groups (1-4, 5-14, 15-24, 25-44 years). The highest cumulative incidence was in 5-14 year olds (59%, 95% credible interval (CI): 52%, 68%) followed by 1-4 year olds (49%, 95% CI: 38%, 61%), rates 20 and 40 times higher respectively than estimated from clinical surveillance. The method provides a more accurate and continuous measure of incidence than achieved by comparing prevalence in samples grouped by time period.

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Related in: MedlinePlus

Changes in seroprevalence and cumulative incidence over time.Estimated changes in seroprevalence and cumulative incidence compared with proportion with HI titer ≥32 by week by age group a) 1–4 years, b) 5–14 years c) 15–24 years d) 25–44 years.
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pone-0017074-g004: Changes in seroprevalence and cumulative incidence over time.Estimated changes in seroprevalence and cumulative incidence compared with proportion with HI titer ≥32 by week by age group a) 1–4 years, b) 5–14 years c) 15–24 years d) 25–44 years.

Mentions: For each age-group, the observed proportions (with 95% CI) of samples with HI titers ≥32 when grouped by week are shown in Figures 4a–d. Also shown is the estimated cumulative seroprevalence and estimated cumulative seroincidence by day, each starting from the baseline at the beginning of the second wave. In contrast to the observed weekly seroprevalences, the estimated cumulative seroprevalence increases monotonically.


Age-specific incidence of A/H1N1 2009 influenza infection in England from sequential antibody prevalence data using likelihood-based estimation.

Baguelin M, Hoschler K, Stanford E, Waight P, Hardelid P, Andrews N, Miller E - PLoS ONE (2011)

Changes in seroprevalence and cumulative incidence over time.Estimated changes in seroprevalence and cumulative incidence compared with proportion with HI titer ≥32 by week by age group a) 1–4 years, b) 5–14 years c) 15–24 years d) 25–44 years.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3044152&req=5

pone-0017074-g004: Changes in seroprevalence and cumulative incidence over time.Estimated changes in seroprevalence and cumulative incidence compared with proportion with HI titer ≥32 by week by age group a) 1–4 years, b) 5–14 years c) 15–24 years d) 25–44 years.
Mentions: For each age-group, the observed proportions (with 95% CI) of samples with HI titers ≥32 when grouped by week are shown in Figures 4a–d. Also shown is the estimated cumulative seroprevalence and estimated cumulative seroincidence by day, each starting from the baseline at the beginning of the second wave. In contrast to the observed weekly seroprevalences, the estimated cumulative seroprevalence increases monotonically.

Bottom Line: This method is applied to derive the cumulative and weekly incidence of A/H1N1 pandemic influenza in England during the second wave using sera taken between September 2009 and February 2010 in four age groups (1-4, 5-14, 15-24, 25-44 years).The highest cumulative incidence was in 5-14 year olds (59%, 95% credible interval (CI): 52%, 68%) followed by 1-4 year olds (49%, 95% CI: 38%, 61%), rates 20 and 40 times higher respectively than estimated from clinical surveillance.The method provides a more accurate and continuous measure of incidence than achieved by comparing prevalence in samples grouped by time period.

View Article: PubMed Central - PubMed

Affiliation: Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency, London, United Kingdom. marc.baguelin@hpa.org.uk

ABSTRACT
Estimating the age-specific incidence of an emerging pathogen is essential for understanding its severity and transmission dynamics. This paper describes a statistical method that uses likelihoods to estimate incidence from sequential serological data. The method requires information on seroconversion intervals and allows integration of information on the temporal distribution of cases from clinical surveillance. Among a family of candidate incidences, a likelihood function is derived by reconstructing the change in seroprevalence from seroconversion following infection and comparing it with the observed sequence of positivity among the samples. This method is applied to derive the cumulative and weekly incidence of A/H1N1 pandemic influenza in England during the second wave using sera taken between September 2009 and February 2010 in four age groups (1-4, 5-14, 15-24, 25-44 years). The highest cumulative incidence was in 5-14 year olds (59%, 95% credible interval (CI): 52%, 68%) followed by 1-4 year olds (49%, 95% CI: 38%, 61%), rates 20 and 40 times higher respectively than estimated from clinical surveillance. The method provides a more accurate and continuous measure of incidence than achieved by comparing prevalence in samples grouped by time period.

Show MeSH
Related in: MedlinePlus