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Hozé N, Diarra I, Sangaré AK, Pastorino B, Pezzi L, Kouriba B, Sagara I, Dabo A, Djimdé A, Thera MA, Doumbo OK, de Lamballerie X, Cauchemez S. Model-based assessment of Chikungunya and O'nyong-nyong virus circulation in Mali in a serological cross-reactivity context. Nat Commun 2021; 12:6735. [PMID: 34795213 PMCID: PMC8602252 DOI: 10.1038/s41467-021-26707-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 09/08/2021] [Indexed: 11/08/2022] Open
Abstract
Serological surveys are essential to quantify immunity in a population but serological cross-reactivity often impairs estimates of the seroprevalence. Here, we show that modeling helps addressing this key challenge by considering the important cross-reactivity between Chikungunya (CHIKV) and O'nyong-nyong virus (ONNV) as a case study. We develop a statistical model to assess the epidemiology of these viruses in Mali. We additionally calibrate the model with paired virus neutralization titers in the French West Indies, a region with known CHIKV circulation but no ONNV. In Mali, the model estimate of ONNV and CHIKV prevalence is 30% and 13%, respectively, versus 27% and 2% in non-adjusted estimates. While a CHIKV infection induces an ONNV response in 80% of cases, an ONNV infection leads to a cross-reactive CHIKV response in only 22% of cases. Our study shows the importance of conducting serological assays on multiple cross-reactive pathogens to estimate levels of virus circulation.
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Affiliation(s)
- Nathanaël Hozé
- Mathematical Modelling of Infectious Diseases Unit, Institut Pasteur, Université de Paris, UMR2000, CNRS, Paris, France
| | - Issa Diarra
- Unité des Virus Émergents, (UVE: Aix-Marseille Univ-IRD 190-INSERM 1207-IHU Méditerranée Infection), Marseille, France
- Malaria Research and Training Center, USTT, Bamako, Mali
| | - Abdoul Karim Sangaré
- Malaria Research and Training Center, USTT, Bamako, Mali
- Centre d'Infectiologie Charles Mérieux, Bamako, Mali
| | - Boris Pastorino
- Unité des Virus Émergents, (UVE: Aix-Marseille Univ-IRD 190-INSERM 1207-IHU Méditerranée Infection), Marseille, France
| | - Laura Pezzi
- Unité des Virus Émergents, (UVE: Aix-Marseille Univ-IRD 190-INSERM 1207-IHU Méditerranée Infection), Marseille, France
- EA7310, Laboratoire de Virologie, Université de Corse-Inserm, Corte, France
| | - Bourèma Kouriba
- Malaria Research and Training Center, USTT, Bamako, Mali
- Centre d'Infectiologie Charles Mérieux, Bamako, Mali
| | - Issaka Sagara
- Malaria Research and Training Center, USTT, Bamako, Mali
| | - Abdoulaye Dabo
- Malaria Research and Training Center, USTT, Bamako, Mali
| | | | | | | | - Xavier de Lamballerie
- Unité des Virus Émergents, (UVE: Aix-Marseille Univ-IRD 190-INSERM 1207-IHU Méditerranée Infection), Marseille, France.
| | - Simon Cauchemez
- Mathematical Modelling of Infectious Diseases Unit, Institut Pasteur, Université de Paris, UMR2000, CNRS, Paris, France
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Eiden J, Volckaert B, Rudenko O, Aitchison R, Herber R, Belshe R, Greenberg H, Coelingh K, Marshall D, Kawaoka Y, Neumann G, Bilsel P. Single Replication M2SR Influenza Vaccine Induced Immune Responses Associated with Protection Against Human Challenge with Highly Drifted H3N2 Influenza Strain. J Infect Dis 2021; 226:83-90. [PMID: 34323977 PMCID: PMC9373152 DOI: 10.1093/infdis/jiab374] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/28/2021] [Indexed: 11/14/2022] Open
Abstract
Background Current influenza vaccines are strain specific and demonstrate low vaccine efficacy against H3N2 influenza disease, especially when vaccine is mismatched to circulating virus. The novel influenza vaccine candidate, M2-deficient single replication (M2SR), induces a broad, multi-effector immune response. Methods A phase 2 challenge study was conducted to assess the efficacy of an M2SR vaccine expressing hemagglutinin and neuraminidase from A/Brisbane/10/2007 (Bris2007 M2SR H3N2; clade 1). Four weeks after vaccination, recipients were challenged with antigenically distinct H3N2 virus (A/Belgium/4217/2015, clade 3C.3b) and assessed for infection and clinical symptoms. Results Adverse events after vaccination were mild and similar in frequency for placebo and M2SR recipients. A single dose of Bris2007 M2SR induced neutralizing antibody to the vaccine (48% of recipients) and challenge strain (27% of recipients). Overall, 54% of M2SR recipients were infected after challenge, compared with 71% of placebo recipients. The subset of M2SR recipients with a vaccine-induced microneutralization response against the challenge virus had reduced rates of infection after challenge (38% vs 71% of placebo recipients; P = .050) and reduced illness. Conclusions Study participants with vaccine-induced neutralizing antibodies were protected against infection and illness after challenge with an antigenically distinct virus. This is the first demonstration of vaccine-induced protection against a highly drifted H3N2 challenge virus.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Yoshihiro Kawaoka
- Influenza Research Institute, University of Wisconsin, Madison, WI, USA
| | - Gabriele Neumann
- Influenza Research Institute, University of Wisconsin, Madison, WI, USA
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3
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Owers Bonner KA, Cruz JS, Sacramento GA, de Oliveira D, Nery N, Carvalho M, Costa F, Childs JE, Ko AI, Diggle PJ. Effects of Accounting for Interval-Censored Antibody Titer Decay on Seroincidence in a Longitudinal Cohort Study of Leptospirosis. Am J Epidemiol 2021; 190:893-899. [PMID: 33274738 DOI: 10.1093/aje/kwaa253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 11/14/2020] [Accepted: 11/16/2020] [Indexed: 12/23/2022] Open
Abstract
Accurate measurements of seroincidence are critical for infections undercounted by reported cases, such as influenza, arboviral diseases, and leptospirosis. However, conventional methods of interpreting paired serological samples do not account for antibody titer decay, resulting in underestimated seroincidence rates. To improve interpretation of paired sera, we modeled exponential decay of interval-censored microscopic agglutination test titers using a historical data set of leptospirosis cases traced to a point source exposure in Italy in 1984. We then applied that decay rate to a longitudinal cohort study conducted in a high-transmission setting in Salvador, Brazil (2013-2015). We estimated a decay constant of 0.926 (95% confidence interval: 0.918, 0.934) titer dilutions per month. Accounting for decay in the cohort increased the mean infection rate to 1.21 times the conventionally defined rate over 6-month intervals (range, 1.10-1.36) and 1.82 times that rate over 12-month intervals (range, 1.65-2.07). Improved estimates of infection in longitudinal data have broad epidemiologic implications, including comparing studies with different sampling intervals, improving sample size estimation, and determining risk factors for infection and the role of acquired immunity. Our method of estimating and accounting for titer decay is generalizable to other infections defined using interval-censored serological assays.
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A method for estimating the transmissibility of influenza using serial cross-sectional seroepidemiological data. J Theor Biol 2020; 511:110566. [PMID: 33347894 DOI: 10.1016/j.jtbi.2020.110566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Seroepidemiological surveillance data has been demonstrated to be useful for estimating the cumulative incidence of influenza, and measures the difference between pre- and post-epidemic seropositive fractions. Despite this, such studies relied on a chosen cut-off value for seropositivity. The aim of the present study is to develop a method to analyze distributions of serial cross-sectional seroepidemiological surveillance datasets using an epidemiological model so that the transmission potential can be estimated without imposing a cut-off value. METHODS A mathematical model of influenza transmission with a discrete antibody titer level was constructed. The final size equation for pre- and post-epidemic titer levels was derived. Subsequently, using the estimated distribution of the dilution increase caused by infection and the measurement error distribution, the model parameters were optimized using the maximum likelihood method. A bootstrap-based confidence interval calculation and sensitivity analysis were also performed. RESULTS Without imposing a cut-off value, the cumulative incidence was quantified, thereby yielding an estimate of the basic reproduction number. For the purpose of exposition, the proposed method was applied to influenza A/Victoria/3/75(H3N2) data, and serological data between 1975 and 1976 were compared. The estimated reproduction number was greater than that using the cut-off value of the hemagglutination inhibition level with titer level 20 (dilution 1:20) or above to define positives. CONCLUSION The proposed method without a cut-off value offers an unbiased approach to estimating the cumulative incidence along with the reproduction number. If a cut-off value is required, the results imply that titer level 20 or above may better represent a reasonable cut-off value for calculating the incidence, but it could underestimate the basic reproduction number.
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Clapham H, Hay J, Routledge I, Takahashi S, Choisy M, Cummings D, Grenfell B, Metcalf CJE, Mina M, Barraquer IR, Salje H, Tam CC. Seroepidemiologic Study Designs for Determining SARS-COV-2 Transmission and Immunity. Emerg Infect Dis 2020; 26:1978-1986. [PMID: 32544053 PMCID: PMC7454079 DOI: 10.3201/eid2609.201840] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Serologic studies are crucial for clarifying dynamics of the coronavirus disease pandemic. Past work on serologic studies (e.g., during influenza pandemics) has made relevant contributions, but specific conditions of the current situation require adaptation. Although detection of antibodies to measure exposure, immunity, or both seems straightforward conceptually, numerous challenges exist in terms of sample collection, what the presence of antibodies actually means, and appropriate analysis and interpretation to account for test accuracy and sampling biases. Successful deployment of serologic studies depends on type and performance of serologic tests, population studied, use of adequate study designs, and appropriate analysis and interpretation of data. We highlight key questions that serologic studies can help answer at different times, review strengths and limitations of different assay types and study designs, and discuss methods for rapid sharing and analysis of serologic data to determine global transmission of severe acute respiratory syndrome coronavirus 2.
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Hoa LNM, Sullivan SG, Mai LQ, Khvorov A, Phuong HVM, Hang NLK, Thai PQ, Thanh LT, Carolan L, Anh DD, Duong TN, Bryant JE, van Doorn HR, Wertheim HFL, Horby P, Fox A. Influenza A(H1N1)pdm09 but not A(H3N2) virus infection induces durable sero-protection: results from the Ha Nam Cohort. J Infect Dis 2020; 226:59-69. [PMID: 32484513 PMCID: PMC9373157 DOI: 10.1093/infdis/jiaa293] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/25/2020] [Indexed: 12/02/2022] Open
Abstract
Background The extent to which influenza recurrence depends upon waning immunity from prior infection is undefined. We used antibody titers of Ha-Nam cohort participants to estimate protection curves and decay trajectories. Methods Households (270) participated in influenza-like–illness (ILI) surveillance and provided blood at intervals spanning laboratory–confirmed virus transmission. Sera were tested in hemagglutination inhibition assay. Infection was defined as influenza virus-positive ILI and/or seroconversion. Median protective titers were estimated using scaled-logistic regression to model pretransmission titer against infection status in that season, limiting analysis to households with infection(s). Titers were modelled against month since infection using mixed-effects linear regression to estimate decay and when titers fell below protection thresholds. Results From December 2008–2012, 295 and 314 participants were infected with H1N1pdm09-like and A/Perth/16/09-like (H3N2Pe09) viruses, respectively. The proportion protected rose more steeply with titer for H1N1pdm09 than for H3N2Pe09, and estimated 50% protection titers were 19.6 and 37.3, respectively. Postinfection titers started higher against H3N2Pe09 but decayed more steeply than against H1N1pdm09. Seroprotection was estimated to be sustained against H1N1pdm09 but to wane by 8-months for H3N2Pe09. Conclusions Estimates indicate that infection induces durable seroprotection against H1N1pdm09 but not H3N2Pe09, which could in part account for the younger age of A(H1N1) versus A(H3N2) cases.
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Affiliation(s)
- Le Nguyen Minh Hoa
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Viet Nam
| | - Sheena G Sullivan
- The WHO Collaborating Centre for Reference and Research on Influenza, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.,Doherty Department, The University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.,Fielding School of Public Health, University of California, Los Angeles, USA
| | - Le Quynh Mai
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Arseniy Khvorov
- Doherty Department, The University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | | | | | - Pham Quang Thai
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Le Thi Thanh
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Louise Carolan
- The WHO Collaborating Centre for Reference and Research on Influenza, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Dang Duc Anh
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Tran Nhu Duong
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Juliet E Bryant
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Viet Nam.,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - H Rogier van Doorn
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Viet Nam.,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Heiman F L Wertheim
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Viet Nam.,Department of Medical Microbiology, Radboudumc, Nijmegen, Netherlands
| | - Peter Horby
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Viet Nam.,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Annette Fox
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Viet Nam.,The WHO Collaborating Centre for Reference and Research on Influenza, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia.,Department of Microbiology and Immunology, The University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
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Hay JA, Minter A, Ainslie KEC, Lessler J, Yang B, Cummings DAT, Kucharski AJ, Riley S. An open source tool to infer epidemiological and immunological dynamics from serological data: serosolver. PLoS Comput Biol 2020; 16:e1007840. [PMID: 32365062 PMCID: PMC7241836 DOI: 10.1371/journal.pcbi.1007840] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 05/21/2020] [Accepted: 04/01/2020] [Indexed: 11/19/2022] Open
Abstract
We present a flexible, open source R package designed to obtain biological and epidemiological insights from serological datasets. Characterising past exposures for multi-strain pathogens poses a specific statistical challenge: observed antibody responses measured in serological assays depend on multiple unobserved prior infections that produce cross-reactive antibody responses. We provide a general modelling framework to jointly infer infection histories and describe immune responses generated by these infections using antibody titres against current and historical strains. We do this by linking latent infection dynamics with a mechanistic model of antibody kinetics that generates expected antibody titres over time. Our aim is to provide a flexible package to identify infection histories that can be applied to a range of pathogens. We present two case studies to illustrate how our model can infer key immunological parameters, such as antibody titre boosting, waning and cross-reaction, as well as latent epidemiological processes such as attack rates and age-stratified infection risk.
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Affiliation(s)
- James A. Hay
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Amanda Minter
- Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Kylie E. C. Ainslie
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Bingyi Yang
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Derek A. T. Cummings
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Adam J. Kucharski
- Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Steven Riley
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
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Tunheim G, Laake I, Robertson AH, Waalen K, Hungnes O, Naess LM, Cox RJ, Mjaaland S, Trogstad L. Antibody levels in a cohort of pregnant women after the 2009 influenza A(H1N1) pandemic: Waning and association with self-reported severity and duration of illness. Influenza Other Respir Viruses 2018; 13:191-200. [PMID: 30536590 PMCID: PMC6379636 DOI: 10.1111/irv.12623] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 11/05/2018] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND A population-based pregnancy cohort was established in Norway to study potential effects of exposure to the 2009 influenza pandemic or pandemic vaccination during pregnancy. OBJECTIVES We studied maternal A(H1N1)pdm09-specific hemagglutination inhibition (HI)-titer levels and waning in women with influenza-like illness (ILI) in pregnancy compared to vaccinated women. Moreover, we studied the association between HI-titers and self-reported severity and duration of ILI. METHODS HI-titers against the pandemic virus were measured in maternal blood samples obtained at birth, 3-9 months after exposure, and linked with information about pregnancy, influenza and vaccination from national registries and a cohort questionnaire. RESULTS Among 1821 pregnant women included, 43.7% were unvaccinated and 19.3% of these had ILI. HI-titers were low (geometric mean titer (GMT) 11.3) in the unvaccinated women with ILI. Higher HI-titers (GMT 37.8) were measured in the vaccinated women. Estimated HI-titer waning was similar for vaccinated women and women with ILI. Most ILI episodes were moderate and lasted 3-5 days. Women with ILI reporting specific influenza symptoms such as fever or cough had higher HI-titers than women without these symptoms. Women who reported being "very ill" or illness duration of >5 days had higher HI-titers than women reporting less severe illness or illness of shorter duration, respectively. CONCLUSIONS Antibody waning was similar in vaccinated women and women with ILI. More severe ILI or longer duration of illness was associated with higher HI-titers. Most unvaccinated pregnant women with ILI had low HI-titers, probably due to moderate illness and HI-titer waning between exposure and sampling.
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Affiliation(s)
- Gro Tunheim
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.,K. G. Jebsen Centre for Influenza Vaccine Research, University of Oslo, Oslo, Norway
| | - Ida Laake
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Anna Hayman Robertson
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Kristian Waalen
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Olav Hungnes
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Lisbeth M Naess
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Rebecca J Cox
- K. G. Jebsen Centre for Influenza Vaccine Research, University of Oslo, Oslo, Norway.,The Influenza Centre, Department of Clinical Science, University of Bergen, Bergen, Norway.,Department of Research and Development, Haukeland University Hospital, Bergen, Norway
| | - Siri Mjaaland
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.,K. G. Jebsen Centre for Influenza Vaccine Research, University of Oslo, Oslo, Norway
| | - Lill Trogstad
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
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9
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Laake I, Tunheim G, Robertson AH, Hungnes O, Waalen K, Håberg SE, Mjaaland S, Trogstad L. Risk of pregnancy complications and adverse birth outcomes after maternal A(H1N1)pdm09 influenza: a Norwegian population-based cohort study. BMC Infect Dis 2018; 18:525. [PMID: 30348103 PMCID: PMC6196446 DOI: 10.1186/s12879-018-3435-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 10/05/2018] [Indexed: 12/04/2022] Open
Abstract
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 hemagglutination-inhibition 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.
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Affiliation(s)
- Ida Laake
- Department of Infectious Disease Epidemiology and Modelling, Norwegian Institute of Public Health, Oslo, Norway.
| | - Gro Tunheim
- Department of Infectious Disease Immunology, Norwegian Institute of Public Health, Oslo, Norway.,K.G. Jebsen Center for Influenza Vaccine Research, University of Oslo, Oslo, Norway
| | - Anna Hayman Robertson
- Department of Infectious Disease Epidemiology and Modelling, Norwegian Institute of Public Health, Oslo, Norway
| | - Olav Hungnes
- Department of Influenza, Norwegian Institute of Public Health, Oslo, Norway
| | - Kristian Waalen
- Department of Influenza, Norwegian Institute of Public Health, Oslo, Norway
| | - Siri E Håberg
- Division for Mental and Physical Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Siri Mjaaland
- Department of Infectious Disease Immunology, Norwegian Institute of Public Health, Oslo, Norway.,K.G. Jebsen Center for Influenza Vaccine Research, University of Oslo, Oslo, Norway
| | - Lill Trogstad
- Department of Infectious Disease Epidemiology and Modelling, Norwegian Institute of Public Health, Oslo, Norway
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10
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Zhao X, Siegel K, Chen MIC, Cook AR. Rethinking thresholds for serological evidence of influenza virus infection. Influenza Other Respir Viruses 2017; 11:202-210. [PMID: 28294578 PMCID: PMC5410725 DOI: 10.1111/irv.12452] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2017] [Indexed: 11/29/2022] Open
Abstract
Introduction For pathogens such as influenza that cause many subclinical cases, serologic data can be used to estimate attack rates and the severity of an epidemic in near real time. Current methods for analysing serologic data tend to rely on use of a simple threshold or comparison of titres between pre‐ and post‐epidemic, which may not accurately reflect actual infection rates. Methods We propose a method for quantifying infection rates using paired sera and bivariate probit models to evaluate the accuracy of thresholds currently used for influenza epidemics with low and high existing herd immunity levels, and a subsequent non‐influenza period. Pre‐ and post‐epidemic sera were taken from a cohort of adults in Singapore (n=838). Bivariate probit models with latent titre levels were fit to the joint distribution of haemagglutination‐inhibition assay‐determined antibody titres using Markov chain Monte Carlo simulation. Results Estimated attack rates were 15% (95% credible interval: 12%‐19%) for the first H1N1 pandemic wave. For a large outbreak due to a new strain, a threshold of 1:20 and a twofold rise (if pared sera is available) would result in a more accurate estimate of incidence. Conclusion The approach presented here offers the basis for a reconsideration of methods used to assess diagnostic tests by both reconsidering the thresholds used and by analysing serological data with a novel statistical model.
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Affiliation(s)
- Xiahong Zhao
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
| | - Karen Siegel
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
| | - Mark I-Cheng Chen
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore.,Communicable Disease Centre, Tan Tock Seng Hospital, Singapore
| | - Alex R Cook
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
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