Low Clinical Burden of 2009 Pandemic Influenza A (H1N1) Infection during Pregnancy on the Island of La Réunion (original) (raw)
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Journal of Infectious Diseases, 2012
Background. Pregnant women were at increased risk for serious outcomes of 2009 pandemic influenza A virus subtype H1N1 (influenza A[H1N1]pdm09) infection, but little is known about the overall impact of the pandemic on neonatal and maternal outcomes. Methods. We identified live births that occurred from 1 July 2008 through 31 May 2010 in 5 Kaiser Permanente regions. Pregnant women were considered to have influenza if they had a positive result of a laboratory test for influenza virus or if they received a diagnosis of influenza during a period in which seasonal influenza virus or A(H1N1)pdm09 was the predominant circulating virus. Results. There were 111 158 births from 109 015 pregnancies involving 107 889 mothers; 368 pregnant women (0.3%) received a diagnosis of influenza due to seasonal virus, and 959 (0.9%) received a diagnosis of influenza due to A(H1N1)pdm09; 107 688 did not receive an influenza diagnosis. Pregnant women with influenza due to A(H1N1)pdm09 were more likely than women with seasonal influenza infection to be hospitalized within 30 days of the diagnosis (27% vs 12%; odds ratio [OR], 2.84 [95% confidence interval {CI}, 2.01-4.02]). Pregnant women with A(H1N1)pdm09 who started antiviral treatment ≥2 days after the diagnosis were significantly more likely to be hospitalized than those who started antiviral treatment <2 days after diagnosis (OR, 3.43 [95% CI, 1.55-7.56]). Mothers with seasonal influenza virus infection had an increased risk for having a small-forgestational-age infant (OR, 1.59 [95% CI, 1.15-2.20]). Conclusions. In this large, geographically diverse population, A(H1N1)pdm09 infection increased the risk for hospitalization during pregnancy. Late initiation of antiviral treatment was also associated with an increased risk for hospitalization.
American Journal of Obstetrics and Gynecology, 2011
T he emergence of 2009 pandemic influenza A (H1N1) virus (2009 H1N1) resulted in the first influenza pandemic in over 40 years. The Centers for Disease Control and Prevention (CDC) estimated that about 61 million people were infected, 274,000 were hospitalized, and about 12,740 died due to 2009 H1N1 in the United States. 1 About 90% of all hospitalizations and 87% of all deaths during the 2009 H1N1 pandemic were among people Ͻ65 years in contrast with experience from seasonal influenza when about 40% of all hospitalizations and 10% of deaths were found in this age group. 1 It is well recognized that pregnancy represents a risk factor for influenza complications and death during both pandemic and seasonal influenza. 2-6 Thus, with illness being widespread among the younger segments of the population We sought to describe characteristics of hospitalized reproductive-aged (15-44 years) women with seasonal (2005/2006 through 2008/2009) and 2009 pandemic influenza A (H1N1) virus infection. We used population-based data from the Emerging Infections Program in 10 US states, and compared characteristics of pregnant (n ϭ 150) and nonpregnant (n ϭ 489) seasonal, and pregnant (n ϭ 489) and nonpregnant (n ϭ 1088) pandemic influenza cases using 2 and Fisher's exact tests. Pregnant women represented 23.5% and 31.0% of all reproductive-aged women hospitalized for seasonal and pandemic influenza, respectively. Significantly more nonpregnant than pregnant women with seasonal (71.2% vs 36.0%) and pandemic (69.7% vs 31.9%) influenza had an underlying medical condition other than pregnancy. Antiviral treatment was significantly more common with pandemic than seasonal influenza for both pregnant (86.5% vs 24.0%) and nonpregnant (82.0% vs 55.2%) women. Pregnant women comprised a significant proportion of influenza-hospitalized reproductive-aged women, underscoring the importance of influenza vaccination during pregnancy.
Postpandemic Influenza A/H1N1pdm09 is still Causing Severe Perinatal Complications
Mediterranean journal of hematology and infectious diseases, 2015
Although influenza A/H1N1pdm09 is not causing a pandemic anymore, we recently observed two critically ill pregnant women infected by this virus. We present these cases to illustrate the possible severe complications of an - at that moment - seasonal influenza in pregnancy. We discuss the epidemiological differences between the pandemic and post pandemic phase and try to explain the high virulence of influenza A/H1N1pdm09 -infections in pregnancy by discussing insights in immunology during pregnancy. We conclude that although influenza A/H1N1pdm09 is in the post pandemic phase, infection by this influenza virus still needs to be considered in pregnant women with progressive respiratory dysfunction.
French Experience of 2009 A/H1N1v Influenza in Pregnant Women
PLoS ONE, 2010
Background: The first reports on the pandemic influenza 2009 A/H1N1v from the USA, Mexico, and Australia indicated that this disease was associated with a high mortality in pregnant women. The aim of this study was to describe and compare the characteristics of severe critically ill and non-severe pregnant women with 2009 A/H1N1v-related illness in France.
Post-pandemic influenza a (H1N1) 2009 virus infection in pregnant women in Ceará, Brazil
Influenza and Other Respiratory Viruses, 2015
The aim of this study was to present results of the postpandemic phase of A(H1N1)pdm09 virus infection in pregnant women in Cear a, Brazil, during the January-June 2012 influenza season. Results One hundred and fifty-four nasopharyngeal swab samples were collected from pregnant women admitted to hospitals with suspected severe acute respiratory infection (SARI). Fifty-three (34Á4%) had laboratory-confirmed A(H1N1)pdm09 virus infection with 15 (28Á3%) outpatients and 38 (71Á7%) hospitalized. Five (9Á4%) women were in the first trimester of pregnancy, 20 (37Á7%) in the second trimester of pregnancy, and 24 (45Á2%) in the third trimester of pregnancy. Three had no information about the time of pregnancy. Six samples from newborns were also analyzed, of which three were nasopharyngeal swab positive for A(H1N1)pdm09. These swabs were collected immediately after birth, with the exception of one that was collected on the day after birth. Conclusion Our findings suggest that transplacental transfer of influenza viruses could occur as a result of severe illness in pregnancy. It is therefore important to encourage women to be vaccinated against influenza in order to avoid pregnancy complications.
BMC Infectious Diseases, 2018
Background: The effects of maternal influenza infection on the fetus remain unclear. We studied mild influenza and influenza antibodies in relation to birth weight and risks of pre-eclampsia, preterm birth (PTB), and small for gestational age (SGA) birth among the unvaccinated participants in the Norwegian Influenza Pregnancy Cohort. Methods: Pregnant women attending a routine ultrasound were recruited from four hospitals in Norway shortly after the 2009 A(H1N1) pandemic. The present study was restricted to unvaccinated participants who were pregnant during the pandemic. Information on the participants was obtained through questionnaires and linkage with national registries. Maternal blood samples were collected at delivery. Women with laboratory-confirmed A(H1N1)pdm09 influenza, a clinical diagnosis of influenza, or self-reported influenza during the pandemic were classified as having had influenza. A(H1N1)pdm09-specific antibodies in serum were detected with the hemagglutinationinhibition assay. Detection of antibodies was considered an indicator of infection during the pandemic in the unvaccinated participants. Odds ratios were estimated with logistic regression. Quantile regression was used to estimate differences in the distribution of birth weight. Results: Among the 1258 women included in this study, there were 37 cases of pre-eclampsia, 41 births were PTB, and 103 births were SGA. 226 women (18.0%) had influenza during the pandemic. The majority of cases did not receive medical care, and only a small proportion (1.3%) of the cases were hospitalized. Thus, the cases consisted primarily of women with mild illness. No significant associations between influenza and risk of pre-eclampsia, PTB, or SGA birth were observed. Detection of A(H1N1)pdm09-specific antibodies was associated with a lower 10th percentile of birth weight, β = − 159 g (95% CI − 309, − 9). Conclusions: Mild influenza illness during pregnancy was not associated with increased risk of pre-eclampsia, PTB or SGA birth. However, influenza infection during pregnancy may reduce the birth weight of the smallest children.
PloS one, 2018
To investigate the factors associated with death and describe the gestational outcomes in pregnant women with influenza A(H1N1)pdm09, we conducted a case-control study (deaths and recovered) in hospitalized pregnant women with laboratory-confirmed influenza A(H1N1)pdm09 with severe acute respiratory illness (SARI) in the state of São Paulo from June 9 to December 1, 2009. All cases were evaluated, and four controls that were matched by the epidemiological week of hospitalization of the case were randomly selected for each case. Cases and controls were selected from the National Disease Notification System-SINAN Influenza-web. The hospital records from 126 hospitals were evaluated, and home interviews were conducted using standardized forms. A total of 48 cases and 185 controls were investigated. Having had a previous health visit to a healthcare provider for an influenza episode before hospital admission was a risk factor for death (adjusted OR (ORadj) of 7.93, 95% CI 2.19-28.69). A...