1322. Antibody Response of Patients with Influenza A (H1N1) pdm09-Associated Pneumonia
Session: Poster Abstract Session: Biomarkers and Correlates of Protection
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
  • PosteFlu_IDSA13_2.png (700.1 kB)
  • Background: Little is known about the dynamics or magnitude of antibody response in patients with influenza A (H1N1) pdm09-associated pneumonia. We therefore described and compared the antibody response to influenza A (H1N1) pdm09 in patients with and without pneumonia.

    Methods: We collected serum samples and determined antibody titers by the hemagglutination inhibition (HI) and microneutralization (mNT) assays from 59 patients with RT-PCR confirmed influenza A (H1N1) pdm09 virus at baseline, 1, 2 and 6 months after onset of illness.

    Results: Forty-five patients (75%) were between the ages of 15 and 60 years, 49 (83%) were hospitalized and 25 (42.3%) had complications with pneumonia. Ninety-four percent of patients were seroprotected (HI titers ≥ 1: 40) and 90% had mNT titers ≥ 1: 160 at 2 months after illness. Geometric mean titers (GMT) of HI and mNT increased significantly (p<0.001) between baseline and months 1 or 2, then declined significantly (p<0.001) at month 6 by HI assay, but dropped to an insignificant level (p=0.24) by mNT assay. The mNT-GMT was at least twice as high as corresponding HI antibodies over a 6 month period. The GMT of HI and mNT in those with pneumonia increased to the peak level earlier than that of those without pneumonia (1 mo vs. 2 mo, respectively). When adjusted by age, those with pneumonia had a higher HI-GMT than those without pneumonia at 1 (264 vs. 177, p=0.011), 2 months (212 vs. 159, p=0.021), and up to 6 months (160 vs. 82, p=0.024).

    Conclusion: The patients, regardless of age, who had recovered from influenza A (H1N1) pdm09-associated pneumonia, clearly developed an earlier and more robust antibody response until 6 months after onset of illness. The results in our study may help to determine an appropriate donor and timing to obtain convalescent plasma for adjunctive treatment of seriously ill patients with pandemic H1N1 influenza.

    Nasikarn Angkasekwinai, MD1, Bualan Kaewnapha2, Duangdao Waywa, MSc1, Peerawong Weerarak, MD1, Sasima Tongsai, Phd1, Kulkanya Chokephaibulkit, MD3, Visanu Thamlikitkul, MD1 and Sontana Siritantikorn, Phd2, (1)Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, (2)Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, (3)Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand


    N. Angkasekwinai, None

    B. Kaewnapha, None

    D. Waywa, None

    P. Weerarak, None

    S. Tongsai, None

    K. Chokephaibulkit, None

    V. Thamlikitkul, None

    S. Siritantikorn, None

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