Infant outcomes among pregnant women who used oseltamivir for treatment of influenza during the H1N1 epidemic

Considerations when treating influenza infections with oseltamivir

INTRODUCTION

Since the coronavirus disease 2019-mandated social distancing policy has been lifted worldwide, the circulation of influenza is expected to resume. Currently, oseltamivir is approved as the first-line agent for influenza prevention and treatment.

AREAS COVERED

This paper reviews the updated evidence in the pharmacology, resistance mechanisms, clinical pharmacy management, and real-world data on oseltamivir for influenza.

EXPERT OPINION

Oseltamivir is an oral prodrug of oseltamivir carboxylate, an influenza A and B neuraminidase inhibitor. Recently, the therapeutic efficacy of oseltamivir has been demonstrated in several trials. Oseltamivir is generally well-tolerated but may lead to neuropsychiatric events and bleeding. Oseltamivir-resistant influenza virus has been associated with the H275Y mutation in the influenza A(H1N1)pdm09 virus, while most strains are still sensitive to oseltamivir. Dose adjustment for oseltamivir should be based on creatinine clearance and body weight in pediatric patients with renal failure. According to real-world data from Nanfang Hospital, the annual number of patients prescribed oseltamivir declined from 35,711 in 2019 to 8,971 in 2020, with marked increases in 2022 (20,213) and 2023 (18,071). Among the 206 inpatients, children aged < 6 years who were treated with oseltamivir had the shortest duration to defervescence.

Influenza antivirals and animal models

Influenza A and B viruses are among the most prominent human respiratory pathogens. About 3-5 million severe cases of influenza are associated with 300 000-650 000 deaths per year globally. Antivirals effective at reducing morbidity and mortality are part of the first line of defense against influenza. FDA-approved antiviral drugs currently include adamantanes (rimantadine and amantadine), neuraminidase inhibitors (NAI; peramivir, zanamivir, and oseltamivir), and the PA endonuclease inhibitor (baloxavir). Mutations associated with antiviral resistance are common and highlight the need for further improvement and development of novel anti-influenza drugs. A summary is provided for the current knowledge of the approved influenza antivirals and antivirals strategies under evaluation in clinical trials. Preclinical evaluations of novel compounds effective against influenza in different animal models are also discussed.

Neonatal outcomes after neuraminidase inhibitor use during pregnancy: A meta-analysis of cohort studies

AIM

Influenza infection poses a severe threat to pregnant mothers, and antiviral treatment is recommended. However, the safety of neuraminidase-inhibitor antiviral medications during pregnancy has not been well described.

METHODS

A systematic review and meta-analysis were performed to evaluate the adverse neonatal outcomes associated with exposure to neuraminidase inhibitors during pregnancy. The PubMed, Embase and Cochrane Library databases were searched to identify potential studies for inclusion.

RESULTS

Nine cohort studies that estimated adverse neonatal outcomes associated with exposure to neuraminidase-inhibitor medication during pregnancy were included. Exposure to a neuraminidase inhibitor during pregnancy was not associated with an increased risk of congenital malformation (odds ratio [OR] 0.9, 95% confidence interval [CI] 0.72-1.12, P = .341), low Apgar score (OR 0.96, 95% CI 0.77-1.2, P = .733) or preterm birth (OR 0.99, 95% CI 0.89-1.09, P = .771) compared with no exposure. However, exposure to a neuraminidase inhibitor was associated with a reduced risk of low birth weight (OR 0.79, 95% CI 0.68-0.92, P = .002) and giving birth to a small-for-gestational-age infant (OR 0.78, 95% CI 0.69-0.88, P < .001). Further analyses limited to oseltamivir exposure were consistent with the overall results.

CONCLUSION

Exposure to neuraminidase-inhibitor medication during pregnancy does not appear to be associated with adverse neonatal outcomes. We recommend further studies to investigate this association, which will help clinicians determine whether to prescribe a neuraminidase inhibitor during pregnancy.

Clinical Effectiveness and Safety of Antivirals for Influenza in Pregnancy

Seasonal influenza epidemics result in substantial health care burden annually. Early initiation of antiviral treatment of influenza has been shown to reduce the risk of complications and duration of illness. Pregnant and postpartum women may be at increased risk for influenza-associated complications; however, pregnant women have been generally excluded from clinical trials of antiviral treatment of influenza. In this review, we summarize the available evidence on the clinical effectiveness and safety of antiviral treatment of pregnant women with influenza. Observational data show a reduction of severe outcomes when pregnant and postpartum women are treated with oseltamivir and other neuraminidase inhibitors without increased risk of adverse maternal, fetal, or neonatal outcomes. Due to lack of safety and efficacy data for baloxavir treatment of pregnant and postpartum women, baloxavir is currently not recommended for use in these populations.

Dengue Virus and Influenza A Virus Co-Infection in Pregnancy: A Case Report

Dengue is still an important cause of disease and mortality in tropical countries, as is influenza A virus, which is also a cause of epidemics all over the globe. In this article, we present the case of a 31-year-old woman who was in her second trimester of pregnancy and presented with severe dengue with hematological and neurological complications, and premature labor. She was misdiagnosed with bacterial infection and received antibiotic treatment with no improvement of the clinical manifestations and previous to death, she was diagnosed with dengue infection. She died from cardiorespiratory arrest. In the postmortem evaluation, influenza A co-infection was confirmed and characterization of the tissue damage and immune response in lung, liver, kidney, heart, spleen, and brain was determined, finding a severe inflammatory response in lung with T cells and macrophages infiltrating the tissue. This case report highlights the risks of accepting a single diagnosis, especially in endemic countries to multiple tropical diseases, which can lead to delay in appropriate treatment that could reduce morbidity and mortality.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Oseltamivir in pregnancy and birth outcomes

Background

Prenatal exposure to influenza or fever is associated with risk of congenital malformations. Oseltamivir is used to treat influenza and to provide post-exposure prophylaxis. We examined the association between oseltamivir use during pregnancy and birth outcomes.

Methods

This was a nationwide registry-based prevalence study with individual level data linkage, in a setting of universal health care access. We included all recorded pregnancies in Denmark in 2002–2013, and used data from population registries to examine associations between dispensings for oseltamivir during pregnancy (first trimester, second/third trimester, none) and congenital malformations, foetal death, preterm birth, foetal growth, and low 5-min Apgar score. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were computed using propensity score matching.

Results

The study included 946,176 pregnancies. Of these, 449 had first-trimester exposure and 1449 had second/third-trimester exposure to oseltamivir. Adjusted ORs following first-trimester exposure were 0.94 (95% CI 0.49 to 1.83) for any major congenital malformation and 1.75 (95% CI 0.51 to 5.98) for congenital heart defects, based on 7 exposed cases. The association with congenital heart defects was present for etiologically implausible exposure periods and for known safe exposures. There was no evidence of an association between prenatal exposure to oseltamivir and any of the other birth outcomes assessed.

Conclusions

The study does not provide evidence of risk associated with oseltamivir treatment additional to that associated with influenza infection.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3423-z) contains supplementary material, which is available to authorized users.

Inhibition of sialidase activity and cellular invasion by the bacterial vaginosis pathogen Gardnerella vaginalis

Bacterial vaginosis is a genital tract infection, thought to be caused by transformation of a lactobacillus-rich flora to a dysbiotic microbiota enriched in mixed anaerobes. The most prominent of these is Gardnerella vaginalis (GV), an anaerobic pathogen that produces sialidase enzyme to cleave terminal sialic acid residues from human glycans. Notably, high sialidase activity is associated with preterm birth and low birthweight. We explored the potential of the sialidase inhibitor Zanamavir against GV whole cell sialidase activity using methyl–umbelliferyl neuraminic acid (MU-NANA) cleavage assays, with Zanamavir causing a 30% reduction in whole cell GV sialidase activity (p < 0.05). Furthermore, cellular invasion assays using HeLa cervical epithelial cells, infected with GV, demonstrated that Zanamivir elicited a 50% reduction in cell association and invasion (p < 0.05). Our data thus highlight that pharmacological sialidase inhibitors are able to modify BV-associated sialidase activity and influence host–pathogen interactions and may represent novel therapeutic adjuncts.

Neuraminidase inhibitors during pregnancy and risk of adverse neonatal outcomes and congenital malformations: population based European register study

Objective To evaluate the possible effects of exposure to neuraminidase inhibitors during embryo-fetal life with respect to adverse neonatal outcomes and congenital malformations.Design Population based multinational observational cohort study and meta-analysis.Setting National registers covering information on maternal healthcare, births, and prescriptions in Denmark, Norway, and Sweden and the EFEMERIS database from the Haute-Garonne district in France.Participants All women together with their singleton infants born between 1 January 2008 and 31 December 2010. Only infants born at 154 days of gestation or later were included. Infants were defined as exposed if the women filled a prescription during pregnancy for either of the two neuraminidase inhibitors oseltamivir or zanamivir.Main outcomes Low birth weight, low Apgar score, preterm birth, small for gestational age birth, stillbirth, neonatal mortality, neonatal morbidity, and congenital malformations. Crude and adjusted hazard ratios of preterm birth were estimated using Cox regression models. Crude and adjusted odds ratios for other outcomes were estimated by logistic regression models.Results The study included 5824 (0.8%) exposed women and their infants and 692 232 who were not exposed. Exposure to neuraminidase inhibitors in utero was not associated with increased risks of any of the investigated neonatal outcomes, including low birth weight (adjusted odds ratio 0.77, 95% confidence interval 0.65 to 0.91), low Apgar score (adjusted odds ratio 0.87, 0.67 to 1.14), preterm birth (adjusted hazard ratio 0.97, 0.86 to 1.10), small for gestational age birth (adjusted odds ratio 0.72, 0.59 to 0.87), stillbirth (adjusted odds ratio 0.81, 0.51 to 1.30), neonatal mortality (adjusted odds ratio 1.13, 0.56 to 2.28), and neonatal morbidity (adjusted odds ratio 0.92, 0.86 to 1.00). No increased risk of congenital malformations overall associated with maternal exposure was observed during the first trimester (adjusted odds ratio 1.06, 0.77 to 1.48). Similarly, no significantly increased risks of any of the outcomes were observed in an analysis restricted to oseltamivir alone.Conclusions This large multinational register study found no increased risks of adverse neonatal outcomes or congenital malformations associated with exposure to neuraminidase inhibitors during embryo-fetal life. The results support previously reported findings that the use of neuraminidase inhibitors is not associated with increased risks of adverse fetal or neonatal outcomes.

Infectious Diseases in Pregnancy

Many infectious diseases have the potential to complicate pregnancy. Some illnesses may only impact maternal health, but others can infect the fetus with possible devastating or long-term sequelae. In this chapter we aim to review common infectious diseases such as urinary tract infections and influenza as well as those that can cause major neonatal morbidity and mortality including TORCH infections. We will also discuss the challenges that pregnancy creates for the management of these infectious diseases as some antibiotics that would typically be used may not be safe for the developing fetus depending on the stage of pregnancy.

Safety of Drugs during Pregnancy and Breastfeeding in Cystic Fibrosis Patients

Health management of cystic fibrosis (CF) patients should be maximized during pregnancy and breastfeeding because of its significant impact on the maternal and newborn outcomes. Thus, numerous drugs will have to be continued during pregnancy and lactation. Most of the drugs representing CF treatment lines cross the placenta or are excreted into human milk. Research addressing the risks and benefits of drugs used in CF patients during pregnancy and lactation is often incomplete or challenged by limited methodology, which often leads to conflicting or inconclusive results. Yet, potential treatment benefits for CF pregnant patients most often outbalance potential risks for the unborn child.

Influenza virus infection in pregnancy: a review

BACKGROUND

Influenza virus infection is very common and a significant cause of morbidity and mortality in specific populations like pregnant women. Following the 2009 pandemic, several reports on the effects of influenza virus infection on maternal health and pregnancy outcome have been published. Also the safety and efficacy of antiviral treatment and vaccination of pregnant women have been studied. In this review, we have analyzed and summarized these data.

OBJECTIVE

To provide information on the influence of influenza virus infection during pregnancy on maternal health and pregnancy outcome and on the effect of treatment and vaccination.

DATA SOURCES

We have searched Medline, Embase and the Cochrane Library. We used influenza, influenz*, pregnancy and pregnan* as search terms.

STUDY SELECTION

In total, 294 reports were reviewed and judged according to the STROBE guidelines or CONSORT statement. In all, 100 studies, published between 1961 and 2015, were included.

RESULTS

Compared to the general population, pregnant women are more often hospitalized and admitted to an intensive care unit due to influenza virus infection. For hospitalized patients, increased rates of preterm birth and fetal/neonatal death are reported. Early treatment with oseltamivir is associated with a reduced risk of severe disease. Vaccination of pregnant women is safe and reduces maternal and neonatal morbidity.

CONCLUSIONS

There is level 2b evidence that maternal health and pregnancy outcome can be severely affected by influenza virus infection. Antiviral treatment may diminish these effects and vaccination protects pregnant women and neonates from infection (level of evidence 2b and 1b, respectively).

Influenza vaccination during pregnancy and its usefulness to mothers and their young infants

The current approach to protecting pregnant women from influenza infection and serious influenza-related complications is vaccination. It is, therefore, critical to evaluate the vaccine's safety, immunogenicity, and protection efficacy during pregnancy. However, because it is affected by previous influenza vaccination or infection, the efficacy of the seasonal trivalent inactivated influenza vaccine is difficult to evaluate in pregnant women. The A/H1N1pdm pandemic in 2009 provided us with the opportunity to evaluate the immunogenicity of the influenza vaccine unaffected by previous vaccinations or infections. Vaccination with inactivated influenza virus during pregnancy elicited neutralizing antibody titers that were sufficient and comparable to those of naturally infected individuals. Furthermore, post-pandemic surveys provided a wealth of definitive information on vaccine efficacy and safety. In addition, transplacental transfer of antibodies following vaccination protected newborn infants against influenza infection. With reports showing the effectiveness of influenza vaccine during pregnancy, it is suggested that influenza vaccination benefits both mothers and their young infants.

Oseltamivir for influenza in pregnancy

Pregnancy predisposes women to disproportionate morbidity and mortality from influenza infections. This is true for both seasonal epidemics as well as occasional pandemics. Inactivated yearly influenza vaccines are the best available method of disease prevention and are recommended for all pregnant women in any trimester of pregnancy and postpartum. Oseltamivir (Tamiflu(®)) is currently the first-line recommended and most commonly used pharmaceutical agent for influenza prophylaxis and treatment. Oseltamivir has been demonstrated to prevent disease among exposed individuals, as well as to shorten the duration of illness and lessen the likelihood of complications among those infected. The physiologic adaptations of pregnancy may alter the pharmacokinetics and pharmacodynamics of this important drug. Updated evidence regarding these potential alterations, current knowledge gaps, and future investigative directions is discussed.

Risk management of seasonal influenza during pregnancy: current perspectives

Influenza poses unique risks to pregnant women, who are particularly susceptible to morbidity and mortality. Historically, pregnant women have been overrepresented among patients with severe illness and complications from influenza, and have been more likely to require hospitalization and intensive care unit admission. An increased risk of adverse outcomes is also present for fetuses/neonates born to women affected by influenza during pregnancy. These risks to mothers and babies have been observed during both nonpandemic and pandemic influenza seasons. During the H1N1 influenza pandemic of 2009-2010, pregnant women were more likely to be hospitalized or admitted to intensive care units, and were at higher risk of death compared to nonpregnant adults. Vaccination remains the most effective intervention to prevent severe illness, and antiviral medications are an important adjunct to ameliorate disease when it occurs. Unfortunately, despite national guidelines recommending universal vaccination for women who are pregnant during influenza season, actual vaccination rates do not achieve desired targets among pregnant women. Pregnant women are also sometimes reluctant to use antiviral medications during pregnancy. Some of the barriers to use of vaccines and medications during pregnancy are a lack of knowledge of recommendations and of safety data. By improving knowledge and understanding of influenza and vaccination recommendations, vaccine acceptance rates among pregnant women can be improved. Currently, the appropriate use of vaccination and antiviral medications is the best line of defense against influenza and its sequelae among pregnant women, and strategies to increase acceptance are crucial. This article will review the importance of influenza in pregnancy, and discuss vaccination and antiviral medications for pregnant women.

Prospective cohort study of the safety of an influenza A(H1N1) vaccine in pregnant Chinese women

To monitor and evaluate the safety of the influenza A(H1N1) vaccine in pregnant women and its influence on the fetus and neonate, we performed a prospective study in which 122 pregnant Chinese women who received the influenza A(H1N1) vaccine and 104 pregnant women who did not receive any vaccine (serving as controls) were observed. The results indicated that the seroconversion rate in the vaccinated group was 90.4% (95% confidence interval [CI], 82.6% to 95.5%). The rate of adverse events following immunization in the pregnant women who received the influenza A(H1N1) vaccine was 3.3%. The spontaneous abortion rates in the vaccinated group and the unvaccinated group were 0.8% and 1.9%, respectively (exact probability test, P = 0.470), the prolonged-pregnancy rates were 8.2% and 4.8%, respectively (χ(2) = 1.041, P = 0.308), the low-birth-weight rates were 1.6% and 0.95%, respectively (exact probability test, P = 1.000), and the spontaneous-labor rates were 70.5% and 75%, respectively (χ(2) = 0.573, P = 0.449). All newborns who have an Apgar score of ≥7 are considered healthy; Apgar scores of ≥9 were observed in 38.5% and 57.7% of newborns in the vaccinated group and the unvaccinated group, respectively (χ(2) = 8.274, P = 0.004). From these results, we conclude that the influenza A(H1N1) vaccine is safe for pregnant women and has no observed adverse effects on fetal growth. (This study has been registered at ClinicalTrials.gov under registration no. NCT01842997.).

Seasonal Human Influenza: Treatment Options

Seasonal influenza can be a self-limiting illness in healthy individuals but is associated with short-term morbidity and economic burden. Influenza can cause significant morbidity and mortality in young children, the elderly, pregnant and post-partum women, patients with co-morbidities and the immunocompromised. Neuraminidase inhibitors (NAIs) are the treatment of choice for influenza due to widespread resistance to the adamantanes. NAIs are efficacious for the treatment of influenza in ambulatory patients with mild illness, when initiated within 48 h of symptom onset. Early treatment with NAIs has been shown to reduce otitis media in children, and lower respiratory tract complications, resulting in antibiotic therapy, in adults. Evidence on the efficacy of NAIs for the prevention of influenza-related complications in at-risk populations, based on reviews of data from randomised trials is inconclusive. However, observational studies suggest that in hospitalised patients early treatment with NAIs has been associated with reduced mortality. NAIs should be initiated as soon as possible in patients at high-risk of influenza-related complications, with suspected or proven influenza, hospitalised patients and patients with severe or progressive disease. NAIs can be considered in previously healthy patients when therapy can be initiated within 48 h of symptom onset. In previously healthy patients, the therapeutic efficacy of oseltamivir is time-dependent, with maximal benefit observed when therapy is initiated within 48 h of symptom onset. However, several observational studies suggest therapeutic benefit beyond 48 h, in hospitalised patients, severe disease, and patients at high risk of complications, including pregnant women. NAIs should be considered in patients at high risk of influenza-related complications who present late. Further studies are needed to define the optimal timing of NAIs. Oseltamivir-resistant virus has been widely reported but is predominantly an issue in H1N1 seasonal influenza. Zanamivir-resistant influenza virus is rare, and inhaled or intravenous (IV) zanamivir is the treatment of choice in proven or suspected oseltamivir-resistant virus. Intubated patients with severe influenza can be treated with oseltamivir (suspension) administered via nasogastric tube. The commercial dry powder formulation of zanamivir should not be administered, via nebulisation, as it has been associated with ventilator malfunction and mortality. In intubated patients, when there are concerns about gastric absorption, IV zanamivir should be obtained under Emergency Investigational New Drug access schemes. Currently available evidence does not support the use of high-dose or extended-duration oseltamivir in patients with severe influenza, but does require further investigation. Extracorporeal membrane oxygenation has not been shown to be superior to conventional management in patients with influenza-associated acute respiratory distress syndrome and should be considered as salvage therapy. Corticosteriods should not be used in the treatment of severe influenza as this has been associated with increased risk of mortality and bacterial superinfection.

Safety of oseltamivir during pregnancy: a comparative study using the EFEMERIS database

OBJECTIVE

To compare pregnancy outcome between women exposed and unexposed to oseltamivir during pregnancy.

DESIGN

A comparative observational cohort study of women exposed to oseltamivir during pregnancy.

SETTING

A French prescription database (EFEMERIS) that includes data for pregnant women was used. EFEMERIS records prescribed and dispensed reimbursed drugs during pregnancy and pregnancy outcomes in Haute-Garonne, South West France.

POPULATION

Women who delivered from 1 July 2004 to 31 December 2010.

METHODS

The study compared exposed and unexposed pregnant women. Two women unexposed to oseltamivir were individually matched, by maternal age, month, and year of delivery, with one women exposed to oseltamivir. Multivariable conditional logistic regression and multivariable Cox proportional hazards regression were used to evaluate associations between each outcome and exposure to oseltamivir during pregnancy.

MAIN OUTCOME MEASURES

Pregnancy loss for any cause, preterm delivery, low birthweight, neonatal pathology, and congenital malformation.

RESULTS

A cohort of 337 (0.58% of women included in EFEMERIS) women exposed to oseltamivir were compared with 674 unexposed women. The risk for pregnancy loss (HR 1.52; 95% CI 0.80-2.91), for preterm birth (adjusted OR 0.64; 95% CI 0.31-1.27), and for neonatal pathology (adjusted OR 0.62; 95% CI 0.23-1.54) did not differ between exposed and unexposed groups. When exposure during organogenesis was considered, one case of congenital anomaly (2.0%) among 49 exposed women and one case (1.0%) among 99 unexposed women were observed (crude OR 2.00; 95% CI 0.13-32.00).

CONCLUSIONS

There was no significant association between adverse pregnancy outcomes and exposure to oseltamivir during pregnancy.