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Günther J, Ziert Y, Andresen K, Pecks U, von Versen-Höynck F. Variability in COVID-19 symptom presentation during pregnancy and its impact on maternal and infant outcomes across the pandemic. Int J Infect Dis 2024; 146:107157. [PMID: 38971556 DOI: 10.1016/j.ijid.2024.107157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 06/21/2024] [Accepted: 06/24/2024] [Indexed: 07/08/2024] Open
Abstract
BACKGROUND With the dominance of different SARS-CoV-2 variants, the severity of COVID-19 has evolved. We aimed to investigate the difference in symptom prevalence and the association between symptoms and adverse pregnancy outcomes during the dominance of Wild-type/Alpha, Delta, and Omicron. METHODS COVID-19 related symptom prevalence, maternal and specific neonatal outcomes of 5431 pregnant women registered in this prospective study were compared considering the dominant virus variant. Logistic regression models analyzed the association between specific symptoms and intensive care unit (ICU) admission or preterm birth. RESULTS Infection with the Delta variant led to an increase in the symptom burden compared to the Wild-type/Alpha variant and the highest risk for respiratory tract symptoms, feeling of sickness, headache, and dizziness/drowsiness. An infection with the Omicron variant was associated with the lowest risk of dyspnea and changes in smell/taste but the highest risk for nasal obstruction, expectoration, headaches, myalgia, and fatigue compared to the Wild-type/Alpha and Delta variant dominant periods. With the progression of the Wild-type/Alpha to the Delta variant neonatal outcomes worsened. Dyspnea and fever were strong predictors for maternal ICU admission and preterm birth independent of vaccination status or trimester of infection onset. CONCLUSION The symptom burden increased during the Delta period and was associated with worse pregnancy outcomes than in the Wild-type/Alpha area. During the Omicron dominance there still was a high prevalence of less severe symptoms. Dyspnea and fever can predict a severe maternal illness.
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Affiliation(s)
- Julia Günther
- Department of Obstetrics, Gynecology and Reproductive Medicine, Hannover Medical School, Hannover, Germany
| | - Yvonne Ziert
- Institute of Biostatistics, Hannover Medical School, Hannover, Germany
| | - Kristin Andresen
- Department of Obstetrics and Gynecology, University Hospital of Schleswig-Holstein, Kiel, Germany
| | - Ulrich Pecks
- Department of Obstetrics and Gynecology, University Hospital of Würzburg, Würzburg, Germany; Maternal Health and Midwifery, Medical faculty of the Julius-Maximilians-University, Würzburg, Germany
| | - Frauke von Versen-Höynck
- Department of Obstetrics, Gynecology and Reproductive Medicine, Hannover Medical School, Hannover, Germany.
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Mahyuddin AP, Swa HLF, Weng R, Zhang J, Dhanaraj JP, Sesurajan BP, Rauff M, Dashraath P, Kanneganti A, Lee R, Wang LF, Young BE, Tambyah PA, Lye DC, Chai LYA, Yee S, Choolani M, Mattar CNZ. COVID-19 vaccination before or during pregnancy results in high, sustained maternal neutralizing activity to SARS-CoV-2 wild-type and Delta/Omicron variants of concern, particularly following a booster dose or infection. Int J Infect Dis 2024; 146:107121. [PMID: 38823622 DOI: 10.1016/j.ijid.2024.107121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 05/21/2024] [Accepted: 05/26/2024] [Indexed: 06/03/2024] Open
Abstract
OBJECTIVES To investigate multi-dose and timings of COVID-19 vaccines in preventing antenatal infection. DESIGN Prospective observational study investigating primary vaccinations, boosters, antenatal COVID-19 infections, neutralizing antibody (Nab) durability, and cross-reactivity to Delta and Omicron variants of concern (VOCs). RESULTS Ninety-eight patients completed primary vaccination prepregnancy (29.6%) and antenatally (63.3%), 24.2% of whom had antenatal COVID-19, while 7.1% were unvaccinated (28.6% had antenatal COVID-19). None had severe COVID-19. Prepregnancy vaccination resulted in vaccination-to-infection delay of 23.3 weeks, which extended to 45.2 weeks with a booster, compared to 16.9 weeks following antenatal vaccination (P < 0.001). Infections occurred at 26.2 weeks gestation in women vaccinated prepregnancy compared to 36.2 weeks gestation in those vaccinated during pregnancy (P < 0.007). The risk of COVID-19 infection was higher without antenatal vaccination (hazard ratio [HR] 14.6, P = 0.05) and after prepregnancy vaccination without a booster (HR 10.4, P = 0.002). Antenatal vaccinations initially led to high Nab levels, with mild waning but subsequent rebound. Significant Nab enhancement occurred with a third-trimester booster. Maternal-neonatal Nab transfer was efficient (transfer ratio >1), and cross-reactivity to VOCs was observed. CONCLUSION Completing vaccination during any trimester delays COVID-19 infection and maintains effective neutralizing activity throughout pregnancy, with robust cross-reactivity to VOCs and efficient maternal-neonatal transfer.
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Affiliation(s)
- Aniza P Mahyuddin
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Hannah L F Swa
- Diagnostics Development Hub, Agency for Science, Technology and Research, Singapore, Singapore
| | - Ruifen Weng
- Diagnostics Development Hub, Agency for Science, Technology and Research, Singapore, Singapore
| | - Jingxian Zhang
- Diagnostics Development Hub, Agency for Science, Technology and Research, Singapore, Singapore
| | - Janice P Dhanaraj
- Diagnostics Development Hub, Agency for Science, Technology and Research, Singapore, Singapore
| | - Binny P Sesurajan
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Mary Rauff
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Department of Obstetrics and Gynaecology, National University Hospital, National University Health System, Singapore, Singapore
| | - Pradip Dashraath
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Department of Obstetrics and Gynaecology, National University Hospital, National University Health System, Singapore, Singapore
| | - Abhiram Kanneganti
- Department of Obstetrics and Gynaecology, National University Hospital, National University Health System, Singapore, Singapore
| | - Rachel Lee
- Department of Obstetrics and Gynaecology, National University Hospital, National University Health System, Singapore, Singapore
| | - Lin-Fa Wang
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, Singapore; The Programme for Research in Epidemic Preparedness and Response (PREPARE), National Centre for Infectious Diseases, Singapore, Singapore
| | - Barnaby E Young
- The Programme for Research in Epidemic Preparedness and Response (PREPARE), National Centre for Infectious Diseases, Singapore, Singapore; National Centre for Infectious Diseases, Singapore, Singapore; Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore; Infectious Diseases Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Paul A Tambyah
- Infectious Diseases Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Division of Infectious Diseases, Department of Medicine, National University Hospital, National University Health System, Singapore, Singapore
| | - David C Lye
- The Programme for Research in Epidemic Preparedness and Response (PREPARE), National Centre for Infectious Diseases, Singapore, Singapore; National Centre for Infectious Diseases, Singapore, Singapore; Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore; Infectious Diseases Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Louis Y A Chai
- Infectious Diseases Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Division of Infectious Diseases, Department of Medicine, National University Hospital, National University Health System, Singapore, Singapore
| | - Sidney Yee
- Innovation and Enterprise, Agency for Science, Technology and Research, Connexis North Tower, Singapore, Singapore
| | - Mahesh Choolani
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Department of Obstetrics and Gynaecology, National University Hospital, National University Health System, Singapore, Singapore
| | - Citra N Z Mattar
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Department of Obstetrics and Gynaecology, National University Hospital, National University Health System, Singapore, Singapore.
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Jarlhelt I, Hansen CB, Pérez-Alós L, Weihe P, Petersen MS, Garred P. SARS-CoV-2 anti-RBD and anti-N protein responses are differentially regulated between mother-child pairs: insight from a national study cohort at the Faroe Islands. Front Immunol 2024; 15:1418678. [PMID: 39021574 PMCID: PMC11251900 DOI: 10.3389/fimmu.2024.1418678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 06/14/2024] [Indexed: 07/20/2024] Open
Abstract
Background Knowledge about SARS-CoV-2 antibody dynamics in neonates and direct comparisons with maternal antibody responses are not well established. This study aimed to characterize and directly compare the maternal and infant antibody response in a national birth cohort from the Faroe Islands. Methods The levels of immunoglobulins (Ig) targeting the receptor binding domain (RBD) of the spike protein and the nucleocapsid protein (N protein) of SARS-CoV-2 were investigated in maternal blood and umbilical cord blood from neonates. The study included 537 neonates and 565 mothers from the Faroe Islands, and follow-up samples were collected 12 months after birth. Multiple linear regression models were used to assess associations of maternal parameters with maternal and neonatal Ig levels and pregnancy outcomes. Results The finding showed that neonates acquired varying levels of SARS-CoV-2 antibodies through transplacental transfer, and the levels were significantly influenced by the mother's vaccination and infection status. The study also found that maternal vaccination and the presence of SARS-CoV-2 antibodies targeting spike RBD were associated with gestational age and APGAR scores. Furthermore, the anti-RBD and -N protein-specific antibody response dynamics during 12 months after birth exhibited differences between mothers and children. RBD and N protein responses were maintained at follow-up in the mother's cohort, while only the N protein response was maintained at follow-up in the children's cohort. Conclusion In conclusion, SARS-CoV-2-specific immune responses in newborns rely on maternal immunity, while the persistence of SARS-CoV-2-specific Igs appears to be differently regulated between mothers and children. The study provides new insights into the dynamics of SARS-CoV-2-specific immune responses in newborns and underscores the nuanced relationship between maternal factors and neonatal humoral responses.
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Affiliation(s)
- Ida Jarlhelt
- Department of Research, The National Hospital of the Faroe Islands, Tórshavn, Faroe Islands
- Center of Health Science, University of the Faroe Islands, Tórshavn, Faroe Islands
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Cecilie Bo Hansen
- Department of Research, The National Hospital of the Faroe Islands, Tórshavn, Faroe Islands
- Center of Health Science, University of the Faroe Islands, Tórshavn, Faroe Islands
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Laura Pérez-Alós
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Pál Weihe
- Department of Research, The National Hospital of the Faroe Islands, Tórshavn, Faroe Islands
- Center of Health Science, University of the Faroe Islands, Tórshavn, Faroe Islands
| | - Maria Skaalum Petersen
- Department of Research, The National Hospital of the Faroe Islands, Tórshavn, Faroe Islands
- Center of Health Science, University of the Faroe Islands, Tórshavn, Faroe Islands
| | - Peter Garred
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Carvalho-Sauer R, Costa MDCN, Teixeira MG, Flores-Ortiz R, Leal JTDFM, Saavedra R, Paixao ES. Maternal and perinatal health indicators in Brazil over a decade: assessing the impact of the COVID-19 pandemic and SARS-CoV-2 vaccination through interrupted time series analysis. LANCET REGIONAL HEALTH. AMERICAS 2024; 35:100774. [PMID: 38828284 PMCID: PMC11143910 DOI: 10.1016/j.lana.2024.100774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 04/28/2024] [Accepted: 05/02/2024] [Indexed: 06/05/2024]
Abstract
Background Few studies have evaluated the effects of the Coronavirus disease 2019 (COVID-19) pandemic, caused by the SARS-CoV-2 virus, on maternal and perinatal health at a populational level. We investigated maternal and perinatal health indicators in Brazil, focusing on the effects of the COVID-19 pandemic, and SARS-CoV-2 vaccination campaign for pregnant women. Methods Utilizing interrupted time series analysis (January 2013-December 2022), we examined Maternal Mortality Ratio, Perinatal Mortality Rate, Preterm Birth Rate, Cesarean Section Rate, and other five indicators. Interruptions occurred at the pandemic's onset (March 2020) and pregnant women's vaccination (July 2021). Results were expressed as percent changes on time series' level and slope. Findings The COVID-19 onset led to immediate spikes in Maternal Mortality Ratio (33.37%) and Perinatal Mortality Rate (3.20%) (p < 0.05). From March 2020 to December 2022, Cesarean Section and Preterm Birth Rates exhibited upward trends, growing monthly at 0.13% and 0.23%, respectively (p < 0.05). Post start of SARS-CoV-2 vaccination (July 2021), Maternal Mortality Ratio (-34.10%) and Cesarean Section Rate (-1.87%) promptly declined (p < 0.05). Subsequently, we observed a monthly decrease of Maternal Mortality Ratio (-9.43%) and increase of Cesarean Section Rate (0.25%) (p < 0.05), while Perinatal Mortality Rate and Preterm Birth Rate showed a stationary pattern. Interpretation The pandemic worsened all analyzed health indicators. Despite improvements in Maternal Mortality Ratio, following the SARS-CoV-2 vaccination campaign for pregnant women, the other indicators continued to sustain altered patterns from the pre-pandemic period. Funding No funding.
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Affiliation(s)
- Rita Carvalho-Sauer
- State Health Department of Bahia, Institute of Collective Health of the Federal University of Bahia, Brazil
| | | | | | - Renzo Flores-Ortiz
- Center for Data and Knowledge Integration for Health (CIDACS), Gonçalo Moniz Institute, Oswaldo Cruz Foundation (FIOCRUZ), Brazil
| | | | - Ramon Saavedra
- State Health Department of Bahia, Institute of Collective Health of the Federal University of Bahia, Brazil
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Horgan R, Hughes BL, Waller J, Hage Diab Y, Saade G. Understanding New Recommendations for Respiratory Syncytial Virus Prevention in Pregnancy. Obstet Gynecol 2024; 143:484-490. [PMID: 38330405 DOI: 10.1097/aog.0000000000005524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 12/14/2023] [Indexed: 02/10/2024]
Abstract
Respiratory syncytial virus (RSV) is a significant cause of infant morbidity and mortality worldwide with peak hospitalization rates for RSV-mediated illnesses between 2 and 3 months of life. Until very recently, prevention strategies for RSV involved primarily passive immunization of neonates at high risk with monoclonal antibodies and promotion of breastfeeding. The Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices now recommends passive immunization of all neonates with monoclonal antibodies during RSV season, and the American Association of Pediatrics has endorsed this practice. The U.S. Food and Drug Administration (FDA) recently approved a vaccination for RSV in pregnancy. The CDC's Advisory Committee on Immunization Practices has recently recommended RSV vaccination for all pregnant patients between 32 and 36 weeks of gestation who are anticipated to deliver during RSV season if they are not planning nirsevimab for their infants. This recommendation has been endorsed by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine. In this clinical perspective, we review the scientific evidence, potential concerns, challenges, and future considerations for RSV vaccination in pregnancy.
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Affiliation(s)
- Rebecca Horgan
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, Virginia; and the Division of Maternal-Fetal Medicine, Duke University, Durham, North Carolina
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Martínez-Quezada R, Miguel-Rodríguez CE, Ramírez-Lozada T, Valencia-Ledezma OE, Acosta-Altamirano G. Placental Transfer Efficiency of Neutralizing Antibodies on SARS-CoV-2 Vaccination before and after Pregnancy in Mexican Women. Int J Mol Sci 2024; 25:1516. [PMID: 38338795 PMCID: PMC10855582 DOI: 10.3390/ijms25031516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 02/12/2024] Open
Abstract
The protection of the neonate against pathogens depends largely on the antibodies transferred placentally from the mother; for this reason, maternal vaccination against emerging viruses, such as SARS-CoV-2, is of vital importance. Knowing some of the immunogenic factors that could alter the placental transfer of antibodies could aid in understanding the immune response and neonatal protection after maternal vaccination. In this study, we analyzed the efficiency of the placental transfer of binding and neutralizing antibodies, as well as some factors that could alter the passive immune response, such as the trimester of gestation at the time of immunization, the number of doses received by the mother and the type of vaccine. Binding IgG antibodies were detected by ELISA, and the detection of neutralizing antibodies was carried out using flow cytometry. Our results show efficient transfer rates (>1), which are higher when maternal vaccination occurs during the third trimester of gestation. Antibodies are detectable in mothers and their neonates after 12 months of maternal immunization, suggesting than the vaccination against COVID-19 before and during pregnancy in the Mexican population induces a lasting neutralizing response in mothers and their newborns.
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Affiliation(s)
- Rebeca Martínez-Quezada
- Unidad de Investigación, Hospital Regional de Alta Especialidad de Ixtapaluca, Carretera Federal México-Puebla Km. 34.5, Pueblo de Zoquiapan, Ixtapaluca 56530, Mexico; (R.M.-Q.); (C.E.M.-R.); (O.E.V.-L.)
- Consejo Mexiquense de Ciencia y Tecnología (COMECYT), Paseo Colón N° 112-A, Ciprés, Toluca 50120, Mexico
| | - Carlos Emilio Miguel-Rodríguez
- Unidad de Investigación, Hospital Regional de Alta Especialidad de Ixtapaluca, Carretera Federal México-Puebla Km. 34.5, Pueblo de Zoquiapan, Ixtapaluca 56530, Mexico; (R.M.-Q.); (C.E.M.-R.); (O.E.V.-L.)
| | - Tito Ramírez-Lozada
- Unidad de Ginecología y Obstetricia, Hospital Regional de Alta Especialidad de Ixtapaluca, Carretera Federal México-Puebla Km. 34.5, Pueblo de Zoquiapan, Ixtapaluca 56530, Mexico;
| | - Omar Esteban Valencia-Ledezma
- Unidad de Investigación, Hospital Regional de Alta Especialidad de Ixtapaluca, Carretera Federal México-Puebla Km. 34.5, Pueblo de Zoquiapan, Ixtapaluca 56530, Mexico; (R.M.-Q.); (C.E.M.-R.); (O.E.V.-L.)
| | - Gustavo Acosta-Altamirano
- Unidad de Investigación, Hospital Regional de Alta Especialidad de Ixtapaluca, Carretera Federal México-Puebla Km. 34.5, Pueblo de Zoquiapan, Ixtapaluca 56530, Mexico; (R.M.-Q.); (C.E.M.-R.); (O.E.V.-L.)
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Regan AK, Arah OA, Fell DB, Sullivan SG. Risk of Severe Maternal Morbidity Associated With Severe Acute Respiratory Syndrome Coronavirus 2 Infection During Pregnancy. Open Forum Infect Dis 2023; 10:ofad613. [PMID: 38143851 PMCID: PMC10745255 DOI: 10.1093/ofid/ofad613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 12/01/2023] [Indexed: 12/26/2023] Open
Abstract
Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during pregnancy increases the risk of adverse fetal and neonatal outcomes, but the contribution to severe maternal morbidity (SMM) has been less frequently documented. Methods We conducted a national cohort study of 93 624 deliveries occurring between 11 March 2020 and 1 July 2021 using medical claims information from the OptumLabs Data Warehouse. SARS-CoV-2 infection was identified from diagnostic and laboratory testing claims records. We identified 21 SMM conditions using International Classification of Diseases, Tenth Revision, Clinical Modification and procedure codes and compared SMM conditions by SARS-CoV-2 status using Poisson regression with robust variance, adjusting for maternal sociodemographic and health factors, onset of labor, and week of conception. Results Approximately 5% of deliveries had a record of SARS-CoV-2 infection: 27.0% <7 days before delivery, 13.5% within 7-30 days of delivery, and 59.5% earlier in pregnancy. Compared to uninfected pregnancies, the adjusted risk of SMM was 2.22 times higher (95% confidence interval [CI], 1.97-2.48) among those infected <7 days before delivery and 1.66 times higher (95% CI, 1.23-2.08) among those infected 7-30 days before delivery. The highest risks were observed for acute respiratory distress syndrome (adjusted risk ratio [aRR], 13.24 [95% CI, 12.86-13.61]) and acute renal failure (aRR, 3.91 [95% CI, 3.32-4.50]). Conclusions COVID-19 is associated with increased rates of SMM.
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Affiliation(s)
- Annette K Regan
- School of Nursing and Health Professions, University of San Francisco, Orange, California, USA
- Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California, USA
| | - Onyebuchi A Arah
- Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California, USA
- Department of Statistics and Data Science, University of California, Los Angeles, Los Angeles, California, USA
| | - Deshayne B Fell
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada
- CHEO Research Institute, Ottawa, Ontario, Canada
| | - Sheena G Sullivan
- Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California, USA
- World Health Organization Collaborating Centre for Reference and Research on Influenza, Melbourne, Victoria, Australia
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