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The 3 waves of the 2009 H1N1 influenza pandemic in Thailand based on national Thai surveillance of influenza-like illness, laboratoryconfirmed cases of A(H1N1)pdm09 and A(H1N1)pdm09-associated deaths (reproduced with permission from Siriraj Med J. 2011;64).
Source publication
Among 368 Thai men who have sex with men with paired serum samples collected before and during the 2009 H1N1 influenza pandemic, we determined influenza A (H1N1)pdm09 seroconversion rates (≥4-fold rise in antibody titers by hemagglutination inhibition or microneutralization assays). Overall, 66 of 232 (28%) participants seroconverted after the firs...
Context in source publication
Context 1
... serum specimens were selected from BMCS participants who had blood drawn at least once during May 2008-May 2009 and at least once during April-July 2010 or January-March 2011. These time points were chosen to obtain baseline serum specimens before A(H1N1)pdm09 circulation in Thailand and follow-up serum specimens either after the first 2 waves or third wave of A(H1N1)pdm09 circulation (Figure 1) [6]. For partic- ipants who had serum specimens available at all 3 time points, paired specimens for after the first waves and after the third wave of the pandemic were treated independently. ...
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Citations
... Data on seroconversion in response to influenza virus infection in Thailand are scarce; no study has reported seroconversion data for seasonal influenza and most studies of seroconversion to influenza A (H1N1)pdm09 virus during the 2009 influenza pandemic focused on seroconversion in special populations (Lerdsamran et al., 2011;Garg et al., 2014;Khuntirat et al., 2014;Simmerman et al., 2011). For instance, using specimens collected in 2009, Lerdsamran et al. reported a substantial influenza A (H1N1) pdm09 virus-specific infection rate among healthy children aged <15 years old compared to healthy adults (Lerdsamran et al., 2011). ...
... For instance, using specimens collected in 2009, Lerdsamran et al. reported a substantial influenza A (H1N1) pdm09 virus-specific infection rate among healthy children aged <15 years old compared to healthy adults (Lerdsamran et al., 2011). A Thai study by Garg et al. reported influenza A (H1N1)pdm09 seroincidence in the population of men who have sex with men between 2009-2011 (Garg et al., 2014). In our study, the overall incidence of influenza virus infection was high (35 infections per 100 person-years). ...
Background:
We measured seroconversion to influenza viruses and incidence of symptomatic influenza virus infection in a cohort of children in Bangkok, Thailand.
Methods:
Children aged ≤6 months were followed for two years for acute respiratory illness (ARI) and had serum specimens taken at 6-month intervals and tested by hemagglutination inhibition (HI) assay. Seroconversion was defined as a >4-fold rise in the HI titers between time points with a titer of >40 in the second specimen. Respiratory swabs were tested by rRT-PCR for influenza. Data were analyzed using generalized linear models.
Results:
Of 350 children, 266 (76%, 147 were healthy and 119 were high-risk) had ≥2 serum specimens collected before influenza vaccination. During the 2-year follow-up, 266 children contributed 370 person-years of observation, excluding post-vaccination periods. We identified 32 ARI cases with rRT-PCR-confirmed influenza virus infection (7 infections/100 person-years, 95% confidence interval [CI], 4-11). There were 126 episodes of influenza virus infection, resulting in a seroconversion rate of 35 infections/100 person-years (95% CI, 30-42). Rates in healthy and high-risk children did not differ.
Conclusions:
Influenza virus infection is common during the first two years of life among Thai children. A large proportion of infections may not be detected using the ARI case definition.
... Focusing on the immune response to the swine flu, according to a recent Thai report, it was found that "seroconversion occurred in approximately one third of the patients with swine flu [8]". It is also reported the observed pattern is not different between HIV-infected and HIV-uninfected cases [9]. Of interest, it seems that the clinical feature in HIV seropositive cases is not different from those with seronegativity. ...
