Figure 1.
Fit of the model to data on replicate measurements.
Observed (red point) and expected (mean: blue point/95% CI: blue bar) number of pairs (observed AT level, replicate AT level). Pairs are sorted by panel according to the number of dilution difference between the observed and the replicate measurement.
Figure 2.
Distribution of paired serology, corrected for measurement errors as a function of season (2008, Spring 2009, Autumn 2009) and subtype (H1N1, H3N2 and B) (in Autumn 2009, subtyping was only conducted for H1N1pdm09).
In each panel, individuals are sorted by baseline AT levels on the y-axis. For a given baseline, the grey bar indicates the expected proportion of individuals with post AT level equal to baseline AT level; the yellow bar indicates the proportion with a 2 fold rise (2f.r.); the red bar indicates the proportion with a 4 fold rise or more (4f.r.+); the green bar indicates the proportion with a decay. The black thin lines give the 95% CI. The legend gives the mean [95% CI]. A: H1N1, 2008. B: H3N2, 2008. C: B, 2008. D: H1N1, Spring 2009. E: H3N2, Spring 2009. F: B, Spring 2009. G: H1N1pdm09, Autumn 2009.
Figure 3.
A: Posterior distribution of the percentage of subjects with a 4 fold rise or more in AT (pink) and with a 2 fold rise or more in AT (blue) for the different subtypes and the different seasons (2008 (08), Spring 2009 (S09), Autumn 2009 (A09)). B: Posterior distribution of the percentage of subjects with a 2 fold rise in AT among those with a rise in AT. Boxplots give percentiles 2.5%, 25%, 50%, 75%, 97.5% of the distribution.
Figure 4.
Distribution of observed increase in PCR positive cases as a function of baseline.
Individuals with a low antibody titer baseline (0–1) are in blue; those with a higher baseline (2–4) are in red.
Figure 5.
Distribution of “observed” paired serology as predicted by the model (color bars) and as observed in the data (black point) as a function of season (2008, Spring 2009, Autumn 2009) and subtype (H1N1, H3N2 and B). In each panel, individuals are sorted by baseline AT levels on the y-axis. For a given baseline, the grey bar indicates the expected proportion of individuals with post AT level equal to baseline AT level; the yellow bar indicates the proportion with a 2 fold rise (2f.r.); the red bar indicates the proportion with a 4 fold rise or more (4f.r.+); the green bar indicates the proportion with a decay. The black thin lines give the 95% CI. The legend gives the mean [95% CI]. A: H1N1, 2008. B: H3N2, 2008. C: B, 2008. D: H1N1, Spring 2009. E: H3N2, Spring 2009. F: B, Spring 2009. G: H1N1pdm09, Autumn 2009.
Figure 6.
Performance of the method to reconstruct the true distribution of paired serology.
Eighty datasets are simulated with known parameters (see Methods). A: Estimated percentage of subjects with an increase in antibody titers as a function of the true percentage in the simulated dataset. B: Estimated percentage of subjects with a decay in antibody titers as a function of the true percentage in the simulated dataset. C: Estimated probabilities characterizing jointly baseline AT level and the change in AT level during the epidemic _ similar to those presented in Figure 1 _ as a function of the true probability in the simulated dataset.
Table 1.
Performance of the method to estimate parameters characterizing measurement errors.
Figure 7.
Less technical description of the statistical method.
This figure illustrates the description of the method that is made in Box 1.