Antibody Dynamics of 2009 Influenza A (H1N1) Virus in Infected Patients and Vaccinated People in China

University of Cape Town, South Africa
PLoS ONE (Impact Factor: 3.23). 02/2011; 6(2):e16809. DOI: 10.1371/journal.pone.0016809
Source: PubMed


To evaluate the risk of the recurrence and the efficiency of the vaccination, we followed-up antibody responses in patients with the 2009 pandemic H1N1 influenza and persons who received the pandemic H1N1 vaccine in Guangzhou China.
We collected serum samples from 129 patients and 86 vaccinated persons at day 0, 15, 30, 180 after the disease onset or the vaccination, respectively. Antibody titers in these serum samples were determined by haemagglutination inhibition (HI) assay using a local isolated virus strain A/Guangdong Liwan/SWL1538/2009(H1N1).
HI antibody positive rate of the patients increased significantly from 0% to 60% at day 15 (χ(2) = 78, P<0.001) and 100% at day 30 (χ(2) = 23, P<0.001), but decreased significantly to 52% at day 180 (χ(2) = 38, P<0.001), while that of vaccinated subjects increased from 0% to 78% at day 15 (χ(2) = 110, P<0.001) and 81% at day 30 (χ(2) = 0.32, P = 0.57), but decreased significantly to 34% at day 180 (χ(2) = 39, P<0.001). Geometric mean titers (GMT) of HI antibodies in positive samples from the patients did not change significantly between day 15 and day 30 (T = 0.92, P = 0.36), but it decreased significantly from 80 at day 30 to 52 at day 180 (T = 4.5, P<0.001). GMT of vaccinated persons increased significantly from 100 at day 15 to 193 at day 30 (T = 4.5, P<0.001), but deceased significantly to 74 at day 180 (T = 5.1, P<0.001). Compared to the patients, the vaccinated subjects showed lower seroconversion rate (χ(2) = 11, P<0.001; χ(2) = 5.9, P = 0.015), but higher GMT (T = 6.0, P<0.001; T = 3.6, P = 0.001) at day 30 and day 180, respectively.
Vaccination of 2009 influenza A (H1N1) was effective. However, about half or more recovered patients and vaccinated persons might have lost sufficient immunity against the recurrence of the viral infection after half a year. Vaccination or re-vaccination may be necessary for prevention of the recurrence.

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Available from: Tiegang Li, Jan 23, 2014
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    • "The level of HI antibody peaks at 1 month, then slightly drops at 2 months, and declines significantly at 6 months while those of NT antibodies did not decline markedly at 6 months after its peak. Similar results were reported by Chen who reported the highest HI-GMT (123, 95% CI 43-356) at days 30-39 after illness onset [22] and by Wang who found a significant decrease of HI-GMT at 6 months [21]. The NT-GMT in our study is two to three times higher than HI-GMT throughout the 6 month period which is similar to those described by Veguilla and colleagues who predicted that the NT titer was generally two to four fold higher than HI titers [5]. "
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    PLoS ONE 11/2013; 8(11):e81436. DOI:10.1371/journal.pone.0081436 · 3.23 Impact Factor
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    • "In the case-control analysis, cases were defined serologically, yet we know that an elevated titer can sometimes be explained by cross-reactions, especially in the elderly [16], and that infected subjects can show a low titer a few months after infection [70]. This lack of specificity and sensitivity to identify infections must be considered in light of the sensitivity analyses results, which often showed similar results with different case definitions. "
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    PLoS ONE 04/2013; 8(4):e60127. DOI:10.1371/journal.pone.0060127 · 3.23 Impact Factor
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    • "First, the antibody against influenza A(H1N1) 2009 acquired by natural infections or vaccination may have decreased. Wang et al reported that at least 50% of the vaccinees and recovered patients lost sufficient immunity after 6 months [23]. The declining herd immunity may have resulted in the severe A(H1N1) 2009 epidemic. "
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