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. 2013 Feb 28;8(2):e57576. doi: 10.1371/journal.pone.0057576

Figure 1. HI antibody reactivity against swH1N1 and H1N1pdm viruses in SWs (Italy, 2008–2010).

Figure 1

Serum samples were collected from swine workers (SWs) in the pre-pandemic peak (15 December 2008–1 November 2009) and post-pandemic peak (2 November 2009–3 October 2010) periods and tested by haemagglutination inhibition (HI) assay. Individual HI results referred to the three cutoff levels (≥10, ≥20 and ≥40) chosen for the statistical analysis of data, and ranging from 10 (minimum level of detection) to 40 (protective antibody titer). No significant difference in seroprevalence rate (SPR) was found in SWs sera tested by HI assay against swH1N1 (Figure 1A) and H1N1pdm (Figure 1B) viruses (viruses details and SPRs are shown in Table 5).