Serum Antibody Response to the Novel Influenza A (H1N1) Virus in the Elderly

Jiang, Tao; Li, Xiaofeng; Yu, Man; Liu, Juan; Yu, Xiao; Qin, E-De; Cao, Wu‐Chun; Leng, Qibin; Qin, Cheng‐Feng

doi:10.1086/649552

Cited by 10 publications

(5 citation statements)

References 4 publications

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“…It is probable that there had already been some degree of previous AH1pdm infection among HCW, despite stringent exclusion criteria. Similar results were reported from Australia and China (2, 15), suggesting that a substantial proportion of the population had been infected with AH1pdm without symptoms. In Japan, cross‐vaccine antibody was only detected in subjects born before 1920 (16).…”

Section: Discussionsupporting

confidence: 84%

Immunogenicity of a monovalent pandemic influenza A H1N1 vaccine in health‐care workers of a university hospital in Japan

Igari

Segawa

Watanabe

et al. 2010

Microbiology and Immunology

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A phase III observational study evaluating a single-dose of an inactivated, split-virus, unadjuvanted AH1pdm vaccine in HCW was conducted. A safe and effective vaccine was needed after the emergence of AH1pdm in April 2009. We analyzed the immunogenicity and safety of the vaccine. A total of 409 subjects were enrolled and given 15 μg hemagglutinin antigen by s.c. injection. Antibody titers were measured using hemagglutination-inhibition antibody assays before vaccination and 28 days after. The co-primary immunogenicity end-points were the proportion of subjects with antibody titers of 1:40 or more, the proportion of subjects with either seroconversion or a significant increase in antibody titer, and the factor increase in geometric mean titer. We collected 389 pair samples. Antibody titers of 1:40 or more were observed in 148 of 389 subjects (38.0%, 95% CI: 33.2-42.9). The immunogenicity was also confirmed in other end-points, but was not sufficient and was lower than in previous reports. A total of 96 of adverse events was reported: 51 local events and 57 systemic events. There were 12 subjects with both local and systemic events. Nearly all events were mild to moderate except in four subjects. A single 15-μg dose of AH1pdm vaccine did not induce sufficient immunogenicity in HCW, with mild-to-moderate vaccine-associated adverse events. We need to consider further improvement of the AH1pdm vaccine program in HCW for the prevention of nosocomial infection, as well as for the benefit of HCW.

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Section: Discussionsupporting

confidence: 84%

Immunogenicity of a monovalent pandemic influenza A H1N1 vaccine in health‐care workers of a university hospital in Japan

Igari

Segawa

Watanabe

et al. 2010

Microbiology and Immunology

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“…Four were commentaries and letters regarding pH1N1 serological studies [24], [25], [26], [27], two studies were duplicates [28], [29], and 29 studies did not match our inclusion criteria. These studies were conducted in Canada [30], China [31], [32], [33], [34], [35], [36], England [37], Finland [38], [39], France [22], Germany [40], Hong Kong [12], India [11], Iran [41], Italy [42], Japan [23], Scotland [43], Singapore [44], [45], [46], [47], [48], Taiwan [49], [50], [51], the United States [2], [52], and a multi-location study that included the United States, Costa Rica, Europe and Japan [53]. We identified one further study on pre-existing pH1N1 immunity in the general population that examined only the molecular basis for immunity [54].…”

Section: Resultsmentioning

confidence: 99%

The Age-Specific Cumulative Incidence of Infection with Pandemic Influenza H1N1 2009 Was Similar in Various Countries Prior to Vaccination

et al. 2011

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BackgroundDuring the influenza pandemic of 2009 estimates of symptomatic and asymptomatic infection were needed to guide vaccination policies and inform other control measures. Serological studies are the most reliable way to measure influenza infection independent of symptoms. We reviewed all published serological studies that estimated the cumulative incidence of infection with pandemic influenza H1N1 2009 prior to the initiation of population-based vaccination against the pandemic strain.Methodology and Principal FindingsWe searched for studies that estimated the cumulative incidence of pandemic influenza infection in the wider community. We excluded studies that did not include both pre- and post-pandemic serological sampling and studies that included response to vaccination. We identified 47 potentially eligible studies and included 12 of them in the review. Where there had been a significant first wave, the cumulative incidence of pandemic influenza infection was reported in the range 16%–28% in pre-school aged children, 34%–43% in school aged children and 12%–15% in young adults. Only 2%–3% of older adults were infected. The proportion of the entire population infected ranged from 11%–18%. We re-estimated the cumulative incidence to account for the small proportion of infections that may not have been detected by serology, and performed direct age-standardisation to the study population. For those countries where it could be calculated, this suggested a population cumulative incidence in the range 11%–21%.Conclusions and SignificanceAround the world, the cumulative incidence of infection (which is higher than the cumulative incidence of clinical disease) was below that anticipated prior to the pandemic. Serological studies need to be routine in order to be sufficiently timely to provide support for decisions about vaccination.

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“…It indicates that the pre-existing immunity and cross-reactivity levels vary in populations and age groups [20]. Seropositivity among elderly in China has been reported to be 9.4% in pre-pandemic and 42.5% in post-pandemic sera [25]. The likely hypotheses being forwarded include the differential exposures [26], the role of cell-mediated immunity [27] and immune epitopes or genetic differences [6].…”

Section: Discussionmentioning

confidence: 99%

Seroepidemiology of pandemic influenza A (H1N1) 2009 virus infections in Pune, India

et al. 2010

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BackgroundIn India, Pune was one of the badly affected cities during the influenza A (H1N1) 2009 pandemic. We undertook serosurveys among the risk groups and general population to determine the extent of pandemic influenza A (H1N1) 2009 virus infections.MethodsPre-pandemic sera from the archives, collected during January 2005 to March 2009, were assayed for the determination of baseline seropositivity. Serosurveys were undertaken among the risk groups such as hospital staff, general practitioners, school children and staff and general population between 15th August and 11th December 2009. In addition, the PCR-confirmed pandemic influenza A (H1N1) 2009 cases and their household contacts were also investigated. Haemagglutination-inhibition (HI) assays were performed using turkey red blood cells employing standard protocols. A titre of ≥1:40 was considered seropositive.ResultsOnly 2 (0.9%) of the 222 pre-pandemic sera were positive. The test-retest reliability of HI assay in 101 sera was 98% for pandemic H1N1, 93.1% for seasonal H1N1 and 94% for seasonal H3N2. The sera from 48 (73.8%) of 65 PCR-confirmed pandemic H1N1 cases in 2009 were positive. Seropositivity among general practitioners increased from 4.9% in August to 9.4% in November and 15.1% in December. Among hospital staff, seropositivity increased from 2.8% in August to 12% in November. Seropositivity among the schools increased from 2% in August to 10.7% in September. The seropositivity among students (25%) was higher than the school staff in September. In a general population survey in October 2009, seropositivity was higher in children (9.1%) than adults (4.3%). The 15-19 years age group showed the highest seropositivity of 20.3%. Seropositivity of seasonal H3N2 (55.3%) and H1N1 (26.4%) was higher than pandemic H1N1 (5.7%) (n = 2328). In households of 74 PCR-confirmed pandemic H1N1 cases, 25.6% contacts were seropositive. Almost 90% pandemic H1N1 infections were asymptomatic or mild. Considering a titre cut off of 1:10, seropositivity was 1.5-3 times as compared to 1:40.ConclusionsPandemic influenza A (H1N1) 2009 virus infection was widespread in all sections of community. However, infection was significantly higher in school children and general practitioners. Hospital staff had the lowest infections suggesting the efficacy of infection-control measures.

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Serum Antibody Response to the Novel Influenza A (H1N1) Virus in the Elderly

Cited by 10 publications

References 4 publications

Immunogenicity of a monovalent pandemic influenza A H1N1 vaccine in health‐care workers of a university hospital in Japan

Immunogenicity of a monovalent pandemic influenza A H1N1 vaccine in health‐care workers of a university hospital in Japan

The Age-Specific Cumulative Incidence of Infection with Pandemic Influenza H1N1 2009 Was Similar in Various Countries Prior to Vaccination

Seroepidemiology of pandemic influenza A (H1N1) 2009 virus infections in Pune, India

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