Seroprevalence following the first wave of pandemic influenza A (H1N1) in Turkey, 2009.
ABSTRACT In this study, we sought to describe the community seropositivity of pandemic influenza A (H1N1) in order to estimate immunity shortly after the peak of the first pandemic wave in two provinces in Turkey. This cross-sectional study was conducted in the provinces of Diyarbakir and Ankara, after the first wave of H1N1 incidences in 2009. It was designed to evaluate 276 houses in Diyarbakir and 455 houses in Ankara. Everyone living in these houses was included in the study. An antibody titer of ≥1:40 was considered as a positive result for all age groups. Antibody titers of ≤1:20 were considered as 1 while calculating the log titer and geometric mean. The pandemic H1N1 seropositivity was found to be 24.1% for Ankara and 27.7% for Diyarbakir. In Ankara, seropositivity was statistically associated with the 15-24 age group (odds ratio [OR] = 11.47), pandemic influenza A (H1N1) vaccination (OR = 20.95), and influenza-like illness history (OR = 1.60). In Diyarbakir, H1N1 seropositivity was associated with the 15-24 age group (OR = 8.99) and pandemic influenza A (H1N1) vaccination (OR = 9.94). Because individuals less than 25 years old played an important role in the community transmission of infection and were largely protected against the pandemic influenza A (H1N1) virus, these individuals should be given a high priority for pandemic influenza vaccination in the event of the emergence of another novel pandemic strain.
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ABSTRACT: Previous influenza pandemics had second and on occasion third waves in many countries that were at times more severe than the initial pandemic waves. This study aims to determine the seroepidemiology of successive waves of H1N1pdm09 infections in Singapore and the overall risks of infection. We performed a cohort study amongst 838 adults, with blood samples provided upon recruitment and at 5 points from 2009 to 2011 and tested by haemagglutination inhibition (HI) with A/California/7/2009 (H1N1pdm09). Surveys on key demographic and clinical information were conducted at regular intervals, and associations between seroconversion and these variables were investigated. After the initial wave from June to September 2009, second and third waves occurred from November 2009 to February 2010 and April to June 2010, respectively. Seroconversion was 13·5% during the first wave and decreased to 6·2% and 6·8% in subsequent waves. Across the three waves, the elderly and those with higher starting HI titres were at lower risk of seroconversion, while those with larger households were at greater risk. Those with higher starting HI titres were also less likely to have an acute respiratory infection. The second and third waves in Singapore had lower serological attack rates than the first wave. The elderly and those with higher HI titres had lower risk, while those in larger households had higher risk of seroconversion.Influenza and Other Respiratory Viruses 07/2013; · 1.47 Impact Factor
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ABSTRACT: In addition to clinical aspects and pathogen characteristics, people's health-related behavior and socioeconomic conditions can affect the occurrence and severity of diseases including influenza A(H1N1)pdm09. A face-to-face interview survey was conducted in a hospital in Mexico City at the time of follow-up consultation for hospitalized patients with pneumonia due to influenza virus infection. In all, 302 subjects were enrolled and divided into two groups based on the period of hospitalization. Among them, 211 tested positive for influenza A(H1N1)pdm09 virus by real-time reverse-transcriptase-polymerase-chain-reaction during the pandemic period (Group-pdm) and 91 tested positive for influenza A virus in the post-pandemic period (Group-post). All subjects were treated with oseltamivir. Data on the demographic characteristics, socioeconomic status, living environment, and information relating to A(H1N1)pdm09, and related clinical data were compared between subjects in Group-pdm and those in Group-post. The ability of household income to pay for utilities, food, and health care services as well as housing quality in terms of construction materials and number of rooms revealed a significant difference: Group-post had lower socioeconomic status than Group-pdm. Group-post had lower availability of information regarding H1N1 influenza than Group-pdm. These results indicate that subjects in Group-post had difficulty receiving necessary information relating to influenza and were more likely to be impoverished than those in Group-pdm. Possible factors influencing time to seeking health care were number of household rooms, having received information on the necessity of quick access to health care, and house construction materials. Health-care-seeking behavior, poverty level, and the distribution of information affect the occurrence and severity of pneumonia due to H1N1 virus from a socioeconomic point of view. These socioeconomic factors may explain the different patterns of morbidity and mortality for H1N1 influenza observed among different countries and regions.PLoS ONE 01/2012; 7(7):e40529. · 3.53 Impact Factor