Safety of oseltamivir in pregnancy: a review of preclinical and clinical data

Adverse outcomes in SARS-CoV-2-infected pregnant mice are gestational age-dependent and resolve with antiviral treatment

SARS-CoV-2 infection during pregnancy is associated with severe COVID-19 and adverse fetal outcomes, but the underlying mechanisms remain poorly understood. Moreover, clinical studies assessing therapeutics against SARS-CoV-2 in pregnancy are limited. To address these gaps, we developed a mouse model of SARS-CoV-2 infection during pregnancy. Outbred CD1 mice were infected at E6, E10, or E16 with a mouse-adapted SARS-CoV-2 (maSCV2) virus. Outcomes were gestational age-dependent, with greater morbidity, reduced antiviral immunity, greater viral titers, and impaired fetal growth and neurodevelopment occurring with infection at E16 (third trimester equivalent) than with infection at either E6 (first trimester equivalent) or E10 (second trimester equivalent). To assess the efficacy of ritonavir-boosted nirmatrelvir, which is recommended for individuals who are pregnant with COVID-19, we treated E16-infected dams with mouse-equivalent doses of nirmatrelvir and ritonavir. Treatment reduced pulmonary viral titers, decreased maternal morbidity, and prevented offspring growth restriction and neurodevelopmental impairments. Our results highlight that severe COVID-19 during pregnancy and fetal growth restriction is associated with heightened virus replication in maternal lungs. Ritonavir-boosted nirmatrelvir mitigated maternal morbidity along with fetal growth and neurodevelopment restriction after SARS-CoV-2 infection. These findings prompt the need for further consideration of pregnancy in preclinical and clinical studies of therapeutics against viral infections.

Adverse outcomes in SARS-CoV-2 infected pregnant mice are gestational age-dependent and resolve with antiviral treatment

SARS-CoV-2 infection during pregnancy is associated with severe COVID-19 and adverse fetal outcomes, but the underlying mechanisms remain poorly understood. Moreover, clinical studies assessing therapeutics against SARS-CoV-2 in pregnancy are limited. To address these gaps, we developed a mouse model of SARS-CoV-2 infection during pregnancy. Outbred CD1 mice were infected at embryonic day (E) 6, E10, or E16 with a mouse adapted SARS-CoV-2 (maSCV2) virus. Outcomes were gestational age-dependent, with greater morbidity, reduced anti-viral immunity, greater viral titers, and more adverse fetal outcomes occurring with infection at E16 (3rd trimester-equivalent) than with infection at either E6 (1st trimester-equivalent) or E10 (2nd trimester-equivalent). To assess the efficacy of ritonavir-boosted nirmatrelvir (recommended for pregnant individuals with COVID-19), we treated E16-infected dams with mouse equivalent doses of nirmatrelvir and ritonavir. Treatment reduced pulmonary viral titers, decreased maternal morbidity, and prevented adverse offspring outcomes. Our results highlight that severe COVID-19 during pregnancy and adverse fetal outcomes are associated with heightened virus replication in maternal lungs. Ritonavir-boosted nirmatrelvir mitigated adverse maternal and fetal outcomes of SARS-CoV-2 infection. These findings prompt the need for further consideration of pregnancy in preclinical and clinical studies of therapeutics against viral infections.

A review of key terminology and definitions used for birth defects globally

Birth defects, also known as congenital disorders, are a significant health issue impacting at least five million births annually worldwide. For policymakers to mount a relevant healthcare response to care for those affected, the burden of disease of these conditions must be quantified. Estimates of the contribution of birth defects to under-5 child mortality and morbidity are generated by several groups globally. These estimates often differ, causing confusion for policymakers. While some differences may be attributed to the data sources and methods used, much is due to a lack of clarity in the terminology used for the group of disorders classed as "congenital". This study aimed to gain insight into the diversity of terms and definitions for birth defects, including those used routinely by relevant international/national organisations and in the peer-reviewed literature. This two-part study included (1) scoping review of peer-reviewed literature to identify terms and definitions in use for birth defects and (2) review of key websites and grey literature to identify terms and definitions used. The results of this study indicate a wide variety of terms being used, often interchangeably and undefined, in peer-reviewed publications, on institutional websites and related literature. This suggests a lack of clarity related to terminology and sets the scene for further discussion, recommending that the community of practice working on birth defects comes to a consensus on standard terminology and definitions for global uptake and implementation. Such standardisation will facilitate a common understanding of the burden of these disorders globally, regionally and within countries so that action can be taken to support affected children and their families.

Human Maternal-Fetal Interface Cellular Models to Assess Antiviral Drug Toxicity during Pregnancy

Pregnancy is a period of elevated risk for viral disease severity, resulting in serious health consequences for both the mother and the fetus; yet antiviral drugs lack comprehensive safety and efficacy data for use among pregnant women. In fact, pregnant women are systematically excluded from therapeutic clinical trials to prevent potential fetal harm. Current FDA-recommended reproductive toxicity assessments are studied using small animals which often do not accurately predict the human toxicological profiles of drug candidates. Here, we review the potential of human maternal-fetal interface cellular models in reproductive toxicity assessment of antiviral drugs. We specifically focus on the 2- and 3-dimensional maternal placental models of different gestational stages and those of fetal embryogenesis and organ development. Screening of drug candidates in physiologically relevant human maternal-fetal cellular models will be beneficial to prioritize selection of safe antiviral therapeutics for clinical trials in pregnant women.

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.

Remdesivir Treatment for COVID 19 in Pregnant Patients with Moderate to Severe Symptoms: Serial Case Report

Introduction: Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) infection that causes novel Coronavirus Disease 2019 (COVID-19) has become a major health problem worldwide and been declared a pandemic since March 2020 by WHO. One special population that poses a challenge is pregnant women with COVID-19. There have not been many studies related to COVID-19 in pregnancy. In this study, we present five serial cases of Remdesivir treatment for COVID-19 in pregnant women with moderate to severe symptoms. Case Illustration: We briefly describe five serial cases being treated with Remdesivir therapy during hospitalization. Four cases were delivered by cesarean section, and one was delivered vaginally in gestation week 37. All cases showed a shortened duration of hospitalization, rapid improvement in clinical symptoms, and no adverse events were observed in mothers, fetuses, and neonates. Discussion: Remdesivir, an inhibitor RNA Polymerase, has been used in COVID-19 treatment and is known to shorten recovery time in nonpregnant women. Some studies have shown no adverse effects on Remdesivir for pregnant women. Based on randomized control trial (RCT) during the Ebola epidemic, Remdesivir was safe to use for pregnant women. All cases showed reduced hospitalization time and better clinical outcomes without maternal, fetal, or neonatal adverse events. Conclusion: Remdesivir protocol for pregnant women with moderate to severe symptoms of COVID-19 has resulted in better clinical improvement with a shorter recovery period and no adverse effects during the hospitalization period. Further studies and RCT are warranted to evaluate the biosafety and effects of Remdesivir in pregnant women.

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.

Management of Pregnancy during the COVID-19 Pandemic

Coronavirus disease 2019 (COVID-19) is spreading worldwide. All aspects of pregnancy management from conception to delivery to puerperium as risks facing newborns are herein, reviewed. Maternal home management and prenatal care management protection, delivery timing or mode selection, delivery process management, and subsequent puerperal protection are crucial. In this Review, the features and treatment strategies, especially emphasizing the safety of antiviral drugs for pregnant women, the wearing of face masks, and practicing of personal hygiene (e.g., handwashing, disinfection, home cleaning, and ventilation) are reviewed as essential protective measures. It is recommended to provide online consultation, telemedicine, and remote fetal heart rate monitoring and set the flow point for prenatal examination to encourage prenatal examination at home or postponing examinations (except nuchal translucency at 11-13+6 weeks, Oscar Test at 16 weeks, and fetal ultrasound at 20-24 weeks). It is shown that the precise formulation of follow-up strategies for pregnant women with COVID-19 is necessary.

COVID-19 Treatment: Drug Safety Prior to Conception and During Pregnancy and Breastfeeding

In December 2019, a new viral respiratory infection known as coronavirus disease 2019 (COVID-19) was first diagnosed in the city of Wuhan, China. COVID-19 quickly spread across the world, leading the World Health Organization to declare it a pandemic on March 11, 2020. The disease is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a similar virus to those involved in other epidemics such as severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). Epidemiological studies have shown that COVID-19 frequently affects young adults of reproductive age and that the elderly and patients with chronic disease have high mortality rates. Little is known about the impact of COVID-19 on pregnancy and breastfeeding. Most COVID-19 cases present with mild flu-like symptoms and only require treatment with symptomatic relief medications, whereas other cases with COVID-19 require treatment in an intensive care unit. There is currently no specific effective treatment for COVID-19. A large number of drugs are being used to fight infection by SARS-CoV-2. Experience with this therapeutic arsenal has been gained over the years in the treatment of other viral, autoimmune, parasitic, and bacterial diseases. Importantly, the search for an effective treatment for COVID-19 cannot expose pregnant women infected with SARS-CoV-2 to the potential teratogenic risks of these drugs. Therefore, it is necessary to determine and understand the safety of anti-COVID-19 therapies prior to conception and during pregnancy and breastfeeding.

A review of the safety of favipiravir - a potential treatment in the COVID-19 pandemic?

Background

Repurposing broad-spectrum antivirals is an immediate treatment opportunity for 2019 coronavirus disease (COVID-19). Favipiravir is an antiviral previously indicated for influenza and Ebola, which has shown some promise in early trials for treatment of COVID-19. We aim to review existing favipiravir safety evidence, which is vital to informing the potential future use of favipiravir in COVID-19.

Methods

A search was conducted across EMBASE and MEDLINE databases, supplemented by relevant grey-literature and ClinicalTrials.gov. All studies assessing the use of favipiravir in humans by 27 March 2020 were considered for inclusion. Further analysis of available safety data from phase 2 and 3 studies was undertaken. Data extracted were adverse events (AEs) grade 1-4, serious AEs and discontinuation for AEs. Specific AEs of interest highlighted in early-phase studies, including gastrointestinal AEs and hyperuricaemia, were also examined.

Results

Twenty-nine studies were identified as potential sources of evidence of the clinical safety of favipiravir. Six were phase 2 and 3 studies reporting relevant safety data for statistical comparison, representing a total of 4299 participants, an estimated 175 person-years-of-follow-up (PYFU). Comparator drugs were oseltamivir, umifenovir, lopinavir/ritonavir or placebo. Study follow-up was between 5 and 21 days. The proportions of grade 1-4 AEs on favipiravir was 28.2% vs 28.4% (P = n.s.) in the comparison arms. The proportion of discontinuations due to AEs on favipiravir was 1.1% vs 1.2% (P = n.s.) in the comparison arms. For serious AEs the proportion was 0.4% in both arms (P = n.s.). There were significantly fewer gastrointestinal AEs occurring on favipiravir vs comparators [8.7% vs 11.5%; P = 0.003]. Favipiravir showed significantly more uric acid elevations than comparators [5.8% vs 1.3%; P<0.0001].

Conclusions

Favipiravir demonstrates a favourable safety profile regarding total and serious AEs. However, safety concerns remain: hyperuricaemia, teratogenicity and QTc prolongation have not yet been adequately studied. Favipiravir may be safe and tolerable in short-term use, but more evidence is needed to assess the longer-term effects of treatment. Given the limitations of the evidence and unresolved safety concerns, caution is warranted in the widespread use of favipiravir against pandemic COVID-19.

Oseltamivir exposure in pregnancy and the risk of specific birth defects

BACKGROUND

Influenza during pregnancy contributes to maternal morbidity and mortality. Neuraminidase inhibitors, including oseltamivir, are recommended for treating women with influenza during pregnancy.

METHODS

Data from the Slone Birth Defects Study from 2009 to 2015 were used to investigate associations between oseltamivir and specific birth defects. We classified exposures according to timing in pregnancy and examined 52 and 16 defects with early and potential late pregnancy etiology, respectively; we calculated crude odds ratios (ORs) and 95% confidence intervals (CIs) for defects with three or more exposures.

RESULTS

Among 8,379 cases and 4,190 nonmalformed controls, we identified 79 and 42 oseltamivir exposures, respectively. The majority of defects had no exposures. ORs were elevated for several defects, but the CI excluded the null only for intestinal malrotation (OR: 10.7 [1.8, 45.2]; three exposures).

CONCLUSIONS

Largely null findings for specific defects are reassuring. The association with intestinal malrotation, while unstable, warrants further investigation.

Use of antiviral drugs for seasonal influenza: Foundation document for practitioners-Update 2019

This document updates the previous AMMI Canada Foundation Guidance (2013) on the use of antiviral therapy for influenza.

A study on mother-to-fetus/infant transmission of influenza A(H7N9) virus: Two case reports and a review of literature

OBJECTIVES

The prevention strategies for mother-to-fetus/infant transmission of H7N9 virus have not been well understood, and the study on this subject will provide further insights.

METHODS

Reverse transcriptase polymerase chain reaction assay was undertaken to detect H7N9 virus in samples from a pregnant women, a postpartum woman, and their fetus/infant. Pathological features of tissues from the dead fetus were evaluated with hematoxylin and eosin staining. Hemagglutination inhibition assay was used to detect virus-specific antibodies. Furthermore, relevant literatures were reviewed and analyzed.

RESULTS

A 28-year-old pregnant woman was hospitalized for H7N9 infection and prescribed with oseltamivir and peramivir for 2 days before admission. The fetal heart beating stopped on day 4, the dead fetus was delivered on day 13, and the woman expired on day 26. All fetal tissues were H7N9 virus-negative. A 28-year-old woman delivered a newborn on December 20, 2016. Five days later, she developed influenza-like symptoms and was confirmed with H7N9 infection. She had close contact with her infant for 9 days. Oseltamivir and peramivir were prescribed within 2 days after illness onset. A throat swab and a pair of serum samples from the infant were all negative for H7N9 virus during 4-week follow-up. In total, ten studies referring to transplacental transmission and four reports on maternal infection of H7N9 virus were reviewed and analyzed.

CONCLUSION

No evidence showed H7N9 virus infection in both fetus and infant. The early administration of neuraminidase inhibitor seemed beneficial in preventing mother-to-fetus/infant transmission of H7N9 virus.

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.

No. 357-Immunization in Pregnancy

OBJECTIVE

To review the evidence and provide recommendations on immunization in pregnancy.

OUTCOMES

Outcomes evaluated include effectiveness of immunization and risks and benefits for mother and fetus.

EVIDENCE

The Medline and Cochrane databases were searched for articles published up to January 2017 on the topic of immunization in pregnancy.

VALUES

The evidence obtained was reviewed and evaluated by the Infectious Diseases Committee of the SOGC under the leadership of the principal authors, and recommendations were made according to guidelines developed by the Canadian Task Force on Preventive Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in this guideline should result in more appropriate immunization of pregnant and breastfeeding women, decreased risk of contraindicated immunization, and better disease prevention.

RECOMMENDATIONS

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.

Optimizing antiviral therapy for influenza: understanding the evidence

Influenza is an important cause of annual epidemics of respiratory viral infection associated with significant morbidity and mortality. Three classes of drugs, the M2 ion channel, neuraminidase and RNA-dependent RNA polymerase inhibitors, are approved for the prevention and treatment of influenza. Due to widespread resistance to the class, the M2 ion channel inhibitors are not recommended currently for therapy. The only polymerase inhibitor, favipiravir, is approved only in Japan and its use is highly restricted. Despite significant data to support the early use of the neuraminidase inhibitors, their use in all patient populations is suboptimal. The data to support the early use of neuraminidase inhibitors will be reviewed, as will current data on the utilization rates in ambulatory and hospitalized populations.

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.

Influenza and its treatment during pregnancy: A review

The influenza viral infection has dramatic effects during pregnancy on the mother and the fetus. We present a review article on the prevention and treatment recommendations of influenza infection in pregnant women, and the effects of antiviral medications on maternal-fetal outcomes. This viral infection not only leads to miscarriages, preterm deliveries and a high maternal mortality rate, but it also poses negative risks to the fetus including small-for-gestational age infants, and admissions to neonatal intensive care units. Vaccination is the most effective strategy for preventing influenza infection during pregnancy whereby can protect both maternal and fetal immunities. The safety profiles of antiviral drugs during pregnancy are limited. Available risk-benefit evidence has indicated that pregnant women with suspected or confirmed influenza should receive prompt antiviral therapy where these medications reduce the risk of complications among pregnant women, and attenuate the teratogenic effects of the influenza infection. Post-exposure prophylaxis is not recommended for most pregnant women, but it may be prescribed in pandemic settings, particularly to non-vaccinated women. Although some ex vivo models for pharmacokinetic studies have revealed that the transplacental transfer of oseltamivir to fetal circuits may occur, there is no evidence of adverse fetal outcomes as a result of most in utero exposures to neuraminidase inhibitors. Due to the large number of confounding variables, large, population-based studies are needed to assess the association between in utero oseltamivir exposure and fetal outcome.

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.

The safety of oseltamivir in pregnancy: an updated review of post-marketing data

PURPOSE

Influenza infection places pregnant women at greater risk of morbidity and hospitalization. The use of oseltamivir to treat influenza increased markedly in all population groups during the A/H1N1pdm09 pandemic, including pregnant women. Given this increase in exposure, a reassessment of the safety of oseltamivir in pregnancy was conducted.

METHODS

The Roche Global Safety Database was searched for all exposures to oseltamivir during pregnancy in the 13 years up to 30 April 2012.

RESULTS

Of the 2926 maternal exposures to oseltamivir retrieved from the Safety Database, pregnancy outcomes were known for 2128 women. Most exposures (>90%) were reported during or after the pandemic. The incidence of adverse pregnancy outcomes in exposed women was: spontaneous abortions, 2.9% (61/2128); therapeutic abortions, 1.8% (39/2128); and pre-term deliveries, 4.2% (84 of 2000 live births), values which are lower than background rates in the general population (women with or without influenza). Fetal outcomes were known in 1875 of the 2926 exposures. For the 81 reported birth defect cases, 11 occurred during the sensitive period for the respective defects. A review of these and other case reports of birth defects did not suggest that they resulted from oseltamivir exposure.

CONCLUSIONS

The data reviewed in this article reinforce the findings of a previous review, suggesting that oseltamivir is unlikely to cause adverse pregnancy or fetal outcomes.

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.

Early prophylactic treatment in pregnant women during the 2009-2010 H1N1 pandemic: obstetric and neonatal outcomes

The aim of the study was to estimate the risk factors associated with the 2009 H1N1 influenza infection, during pregnancy; to describe complications and obstetric and perinatal outcomes of pregnancies during the H1N1 pandemic in 2009; to identify if there is teratogenicity at birth after antiviral treatment. Medical records of 168 pregnant women treated in Reina Sofia University Hospital (Cordoba, Spain) for suspected influenza A H1N1 from September 2009 to February 2010 were analysed. Using the PCR test, 76 pregnant women were diagnosed with H1N1 + infection, and infection was ruled out in the remaining 92. To manage the pandemic, recommendations of the Centres for Disease Control and Prevention were followed. Results showed that the majority of pregnant women were attended at the hospital between October and December 2009 (91.27%). Most of them were in the third-quarter of pregnancy (42.9%). In our sample, being aged between 29 and 37 years reduces the risk of acquiring infection (odds ratio, OR 0.379, 95% confidence interval, CI 0.188-0.763). However, in pregnant women who have required hospitalisation, the risk of infection increased five-fold (OR = 4.999; 95% CI = 1.178-21.212). No differences were found between obstetric and perinatal outcomes of both affected and unaffected or treated and untreated cohorts. No teratogenicity was observed at birth. It was concluded that maternal age and 3rd trimester pregnancy were found related to the risk of acquiring H1N1. No differences in obstetric outcomes or worse perinatal outcomes were found in patients affected by the pandemic. Early prophylactic treatment may be related to better maternal-fetal results.

Clinical focus: infections in pregnancy

Pregnant women are particularly susceptible to a number of infectious diseases, such as influenza, hepatitis E, malaria, and tuberculosis. The management of many other infections-including urinary tract infections, human immunodeficiency virus, and sexually transmitted diseases-is also made more complex by pregnancy; even if some infections do not pose a great risk to the expectant mother, they can impact fetal and neonatal development, thus posing a treatment challenge to physicians. By focusing on the most important diseases that physicians may encounter in pregnant patients, this review outlines the challenges associated with managing important infectious diseases in the pregnant population and references the most recent evidence and international treatment guidelines.

Outcomes of infants exposed to oseltamivir or zanamivir in utero during pandemic (H1N1) 2009

OBJECTIVE

To assess adverse fetal outcomes and short-term prognoses of infants exposed to oseltamivir or zanamivir in utero during pandemic (H1N1) 2009 in Japan.

STUDY DESIGN

Case series study. We asked the 2611 obstetric facilities in Japan that are members of the Japan Society of Obstetrics and Gynecology to participate, and data were provided from 157 facilities. We evaluated the numbers of pregnancy complications and neonatal abnormalities.

RESULTS

We evaluated 624 infants born to 619 women given oseltamivir and 50 infants born to 50 women given zanamivir. Of patients given oseltamivir before gestational week 22, 3 experienced miscarriage and 1 experienced induced abortion. The overall rate of congenital malformations was 2.1% (14/670). In infants exposed during the first trimester, the rate of malformations was 1.3% (2/156) with oseltamivir and 0.0% (0/15) with zanamivir, although in infants exposed during the second and third trimesters, this rate was 2.6% (12/464) with oseltamivir and 0.0% (0/35) with zanamivir. Increased rates of miscarriage in women given antiviral drugs before gestational week 22 (0.9% [3/322]), preterm delivery in women given antiviral drugs before gestational week 37 (5.5% [33/600]), stillbirth (0% [0/670]), neonatal death (0.15% [1/670]), birthweight <2500 g (8.7% [58/670]), small-for-gestational-age infants (8.4% [56/670]), necrotizing enterocolitis (0.0%), intraventricular hemorrhage (0.0%), seizures (0.15% [1/670]), and other transient abnormalities in the neonatal period (4.3% [29/670]) were not observed in those exposed to antiviral drugs before the corresponding episodes or complications.

CONCLUSION

Short-term prognoses of infants exposed to oseltamivir or zanamivir in utero were not adversely affected.

Clinical use of approved influenza antivirals: therapy and prophylaxis

Currently, there are two commonly used classes of antiviral agents approved for the prevention of and treatment for influenza: the M2 Inhibitors (amantadine and rimantadine) and the neuraminidase inhibitors (oseltamivir, laninamivir, peramivir and zanamivir). These agents have been proven to be safe and effective alone or in combination for the treatment of uncomplicated influenza in otherwise healthy individuals. Although there are few prospective, randomized studies of these antivirals for the treatment of pregnant women, hospitalized patients, and immunocompromised patients infected with seasonal, pandemic, or avian H5N1 influenza, these agents are widely used for these indications. This article reviews the pharmacokinetics and clinical data available relative to the use of commercially available antiviral agents for the prevention of and treatment for influenza.

[Influenza infection and pregnancy]

Pregnant woman have an increased risk of respiratory complications and hospitalization related to influenza. The flu, like any systemic infection, may also be responsible for uterine contractions constituting a threat of miscarriage or premature labor according to gestational age at which it occurs. There is no specific recommendation regarding the management of influenza-like illness in pregnant women, but a nasopharyngeal sample can be performed in the presence of respiratory or general symptoms occurring during an epidemic to search influenza and establish if a specific treatment with oseltamivir (Tamiflu(®)). Surveillance in hospital or intensive care unit may be necessary. Vaccination against influenza provides a satisfactory immunity in pregnant women and reduces the risk of respiratory complications. Transplacental passage of maternal antibody protects newborns who are more likely to have severe influenza infection and because the vaccine cannot be administered before the age of 6 months. The available data show good tolerance influenza vaccination performed during pregnancy. Since 2012, vaccination against seasonal influenza is recommended for pregnant women, whatever the stage of pregnancy at the time of the vaccination campaign.

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

OBJECTIVE

This study was undertaken to examine the association between maternal oseltamivir treatment for influenza and infant outcomes during the 2009 HINI influenza pandemic.

STUDY DESIGN

This was a retrospective cohort study using a population-based maternal newborn database including women who gave birth to a singleton infant in the Canadian province of Ontario from November 2009 through April 2010. Risks of small for gestational age (SGA) (10th percentile and 3rd percentile), preterm birth (<37 weeks of gestation), very preterm birth (<32 weeks of gestation), and 5-minute Apgar score <7 associated with maternal exposure to oseltamivir were analyzed by multivariable regression.

RESULTS

A total of 55,355 women with a singleton birth were included in this study. Among them, 1237 (2.2%) women received oseltamivir for treatment or prevention of influenza during pregnancy. Women who took oseltamivir during pregnancy were less likely to have a SGA infant based on the 10th percentile for growth (adjusted risk ratio, 0.77; 95% confidence interval, 0.60-0.98). No association between maternal use of oseltamivir with SGA on 3rd percentile, preterm birth, very preterm birth, and low Apgar score was observed.

CONCLUSION

There is no evidence of an association between maternal use of oseltamivir for influenza and early birth, low Apgar at birth, and poor fetal growth.

Management of influenza infection in solid-organ transplant recipients: consensus statement of the Group for the Study of Infection in Transplant Recipients (GESITRA) of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) and the Spanish Network for Research in Infectious Diseases (REIPI)

BACKGROUND

Solid organ transplant (SOT) recipients are at greater risk than the general population for complications and mortality from influenza infection.

METHODS

Researchers and clinicians with experience in SOT infections have developed this consensus document in collaboration with several Spanish scientific societies and study networks related to transplant management. We conducted a systematic review to assess the management and prevention of influenza infection in SOT recipients. Evidence levels based on the available literature are given for each recommendation. This article was written in accordance with international recommendations on consensus statements and the recommendations of the Appraisal of Guidelines for Research and Evaluation II (AGREE II).

RESULTS

Recommendations are provided on the procurement of organs from donors with suspected or confirmed influenza infection. We highlight the importance of the possibility of influenza infection in any SOT recipient presenting upper or lower respiratory symptoms, including pneumonia. The importance of early antiviral treatment of SOT recipients with suspected or confirmed influenza infection and the necessity of annual influenza vaccination are emphasized. The microbiological techniques for diagnosis of influenza infection are reviewed. Guidelines for the use of antiviral prophylaxis in inpatients and outpatients are provided. Recommendations for household contacts of SOT recipients with influenza infection and health care workers in close contact with transplant patients are also included. Finally antiviral dose adjustment guidelines are presented for cases of impaired renal function and for pediatric populations.

CONCLUSIONS

The latest scientific information available regarding influenza infection in the context of SOT is incorporated into this document.

Oseltamivir and inhaled zanamivir as influenza prophylaxis in Thai health workers: a randomized, double-blind, placebo-controlled safety trial over 16 weeks

OBJECTIVES

Long-term chemoprophylaxis using neuraminidase inhibitors may be needed during influenza epidemics but safety data are limited to several weeks. We sought to assess the tolerability of oseltamivir and zanamivir as primary prophylaxis over 16 weeks.

METHODS

We conducted a parallel group, double blind, 2 (active drug) :1 (placebo) randomized trial of oral oseltamivir/placebo or inhaled zanamivir/placebo over 16 weeks in healthy, Thai hospital professionals at two Bangkok hospitals. The primary endpoint was study withdrawal due to drug-related (possibly, probably, definitely) serious or adverse events (AEs) graded ≥ 2.

RESULTS

Recruited subjects numbered 129 oseltamivir/65 placebo and 131 zanamivir/65 placebo. A total of 102 grade ≥ 2 AEs were reported or detected in 69 subjects: 23/129 (17.8%) versus 15/65 (23.1%) (P=0.26), and 23/131 (17.6%) versus 8/65 (12.3%) (P=0.28). Intercurrent infections/fevers [26/102 (25.5%)], abnormal biochemistry [25/102 (24.5%)] and gastrointestinal symptoms [18/102 (17.6%)] were the most frequently reported AEs. There were no drug-related study withdrawals. Eight serious AEs were all due to intercurrent illnesses. Laboratory, lung function and ECG parameters were similar between drugs and placebos.

CONCLUSIONS

Oseltamivir and zanamivir were well tolerated in healthy hospital professionals. Both drugs can be recommended for primary influenza prophylaxis for up to 16 weeks.

Influenza in pregnancy

Please cite this paper as: Memoli et al. (2012) Influenza in pregnancy. Influenza and Other Respiratory Viruses 00(00), 000–000.

The 2009 pandemic served as a strong reminder that influenza‐induced disease can have a great impact on certain at‐risk populations and that pregnant women are one such important population. The increased risk of fatal and severe disease in these women was appreciated more than 500 years ago, and during the last century, pregnant women and their newborns have continued to be greatly affected by both seasonal and pandemic influenza. In this review, we briefly discuss the data collected both before and after the 2009 pandemic as it relates to the impact of influenza on pregnant women and their fetuses/newborns, as well as risk variables, clinical features, clues to pathophysiologic mechanisms, and approaches to treatment and prevention.

Chemical analysis and transplacental transfer of oseltamivir and oseltamivir carboxylic acid in pregnant rats

In view of the limited information on the pharmacokinetics of oseltamivir (OSE) during pregnancy, this study aims to evaluate the placental transportation of OSE and its active metabolite oseltamivir carboxylic acid (OCA) in rats. A validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) system coupled to an in vivo transplacental model has been developed to determine OSE and OCA in the placenta, amniotic fluids and fetus of 13-day pregnant Sprague-Dawley rats. Concentrations of OSE and OCA in plasma, amniotic fluids, placenta, and fetus were measured by the validated LC-MS/MS after OSE administration (10 mg/kg, iv). The pharmacokinetic data of both analytes were examined by non-compartmental modeling. The area under the concentration-time curve (AUC) of OCA in maternal plasma was found to be 3.6 times larger than that of OSE. The AUCs of OCA in both amniotic fluid and fetus were significantly decreased, in comparison with that in maternal plasma (reduced by 76.7 and 98.1%, respectively). We found that both OSE and OCA can penetrate the placenta, amniotic fluids and fetus in rats during pregnancy; however, the penetration of OCA was much lower than that of OSE. The mother-to-fetus transfer ratio was defined as AUC_fetus/AUC_mother. The data demonstrated that the mother-to-fetus transfer ratio of OSE and OCA were 1.64 and 0.019, respectively, suggesting that OSE, but not OCA, penetrated through the placenta. Moreover, OCA might not be easily metabolized in the fetus due to the lack of carboxylase in the fetus.

The comparative clinical course of pregnant and non-pregnant women hospitalised with influenza A(H1N1)pdm09 infection

INTRODUCTION

The Influenza Clinical Information Network (FLU-CIN) was established to gather detailed clinical and epidemiological information about patients with laboratory confirmed A(H1N1)pdm09 infection in UK hospitals. This report focuses on the clinical course and outcomes of infection in pregnancy.

METHODS

A standardised data extraction form was used to obtain detailed clinical information from hospital case notes and electronic records, for patients with PCR-confirmed A(H1N1)pdm09 infection admitted to 13 sentinel hospitals in five clinical 'hubs' and a further 62 non-sentinel hospitals, between 11th May 2009 and 31st January 2010.Outcomes were compared for pregnant and non-pregnant women aged 15-44 years, using univariate and multivariable techniques.

RESULTS

Of the 395 women aged 15-44 years, 82 (21%) were pregnant; 73 (89%) in the second or third trimester. Pregnant women were significantly less likely to exhibit severe respiratory distress at initial assessment (OR = 0.49 (95% CI: 0.30-0.82)), require supplemental oxygen on admission (OR = 0.40 (95% CI: 0.20-0.80)), or have underlying co-morbidities (p-trend <0.001). However, they were equally likely to be admitted to high dependency (Level 2) or intensive care (Level 3) and/or to die, after adjustment for potential confounders (adj. OR = 0.93 (95% CI: 0.46-1.92). Of 11 pregnant women needing Level 2/3 care, 10 required mechanical ventilation and three died.

CONCLUSIONS

Since the expected prevalence of pregnancy in the source population was 6%, our data suggest that pregnancy greatly increased the likelihood of hospital admission with A(H1N1)pdm09. Pregnant women were less likely than non-pregnant women to have respiratory distress on admission, but severe outcomes were equally likely in both groups.

Transplacental transfer of oseltamivir and its metabolite using the human perfused placental cotyledon model

OBJECTIVE

Given the lack of data regarding the use of oseltamivir (Tamiflu) during pregnancy, we aimed to evaluate the placental transfer of oseltamivir phosphate and its active metabolite oseltamivir carboxylate, using the perfused placental cotyledon model.

STUDY DESIGN

Cotyledons were coperfused with oseltamivir phosphate and oseltamivir carboxylate using the maximal concentrations described with a 75 mg, twice-daily oral dose. Main transfer parameters such as fetal transfer rate (FTR) and clearance index (CI) were assessed.

RESULTS

Five placentas were coperfused with oseltamivir phosphate and oseltamivir carboxylate. The median FTR of oseltamivir phosphate was 8.5% (range, 5.0-11.6%) and the median CI was 0.3 (range, 0.2-0.6). Regarding oseltamivir carboxylate transplacental transfer, the median FTR was 6.6% (range, 3.9-9.7%), whereas the median CI was 0.2 (range, 0.2-0.5).

CONCLUSION

A transplacental transfer of oseltamivir phosphate and its metabolite oseltamivir carboxylate was detected and might have clinical relevance. Clinicians should be encouraged to report oseltamivir treatment outcomes during pregnancy.

The use of antiviral drugs for influenza: Guidance for practitioners 2012/2013

The present article addresses the use of antiviral drugs in the management of seasonal influenza illness for the 2012/2013 season. It updates the previous document published in 2011 (1). Noteworthy guidance updates since 2011 include the following: Seasonal influenza in 2012/2013 is predicted to be caused by two human influenza A and one influenza B strain, all of which are anticipated to remain generally susceptible to oseltamivir.The predicted strains are A/California/7/2009 (H1N1) pdm09-like, A/Victoria/361/2011 (H3N2)-like and B/Wisconsin/1/2010-like (Yamagata lineage). All are included in the seasonal influenza vaccine and are susceptible to oseltamivir.Swine-variant H3N2v, which has rarely caused infection in humans exposed to infected swine within the past year in the United States, is susceptible to oseltamivir. It is not included in the current seasonal influenza vaccine.It is still considered that initiation of antiviral therapy more than 36 h to 48 h after onset of symptoms is beneficial in patients hospitalized with complicated influenza and severe illness.Oseltamivir continues to be recommended for the treatment of influenza in pregnant women.The use of antiviral drugs among measures to control outbreaks of influenza in closed facilities such as correctional institutions is now included in the present document.

Oseltamivir in seasonal, pandemic, and avian influenza: a comprehensive review of 10-years clinical experience

Oseltamivir (Tamiflu®; F. Hoffmann-La Roche Ltd, Basel, Switzerland) is an orally administered antiviral for the treatment and prevention of influenza A and B infections that is registered in more than 100 countries worldwide. More than 83 million patients have been exposed to the product since its introduction. Oseltamivir is recommended by the World Health Organization (WHO) for use in the clinical management of pandemic and seasonal influenza of varying severity, and as the primary antiviral agent for treatment of avian H5N1 influenza infection in humans. This article is a nonsystematic review of the experience gained from the first 10 years of using oseltamivir for influenza infections since its launch in early 2000, emphasizing recent advances in our understanding of the product and its clinical utility in five main areas. The article reviews the pharmacokinetics of oseltamivir and its active metabolite, oseltamivir carboxylate, including information on special populations such as children and elderly adults, and the co-administration of oseltamivir with other agents. This is followed by a summary of data on the effectiveness of oseltamivir treatment and prophylaxis in patients with all types of influenza, including pandemic (H1N1) 2009 and avian H5N1 influenza. The implications of changes in susceptibility of circulating influenza viruses to oseltamivir and other antiviral agents are also described, as is the emergence of antiviral resistance during and after the 2009 pandemic. The fourth main section deals with the safety profile of oseltamivir in standard and special patient populations, and reviews spontaneously reported adverse event data from the pandemic and pre-pandemic periods and the topical issue of neuropsychiatric adverse events. Finally, the article considers the pharmacoeconomics of oseltamivir in comparison with vaccination and usual care regimens, and as a component of pandemic influenza mitigation strategies.

Antivirals and resistance: influenza virus

Influenza causes annual epidemics of respiratory viral infections are associated with significant morbidity and mortality. Influenza vaccines have been shown to reduce the risk of infection and mitigate against some of the virus' sequellae. Likewise, two classes of antivirals, the adamantanes (amantadine and rimantadine) and the neuraminidase inhibitors (laninamivir, oseltamivir, peramivir, and zanamivir) are currently approved for the prevention and treatment of influenza; several other classes of antivirals and immune modulators are also currently under investigation. One of the greatest challenges to our armamentarium of antivirals is the emergence of resistant mutants. In this paper, we will review the currently approved and investigational antiviral agents and the mechanisms of resistance that impact their activity.

Volkmann ischemic contracture in a newborn

Congenital Volkmann ischemic contracture is a very rare condition in which a neonate presents skin, muscular and nerve lesions due to increased intracompartment pressure and subsequent ischemia, probably due to extrinsic intrauterine compression. In this age group, there are only about 50 reported cases and a specific cause is unknown. The authors describe the case of a newborn who presented with bullous and ulcerated skin lesions and nerve palsy of his forearm at birth, evolving to subcutaneous and muscular necrosis and contracture. Two surgeries were performed and the baby began a daily physiotherapy program that resulted in aesthetical improvement and recovery of his hand and forearm mobility. Early recognition of this rare entity and subsequent emergency fasciotomy are the best ways to improve prognosis.

Safety profile of oseltamivir during the 2009 influenza pandemic

PURPOSE

This study evaluated the safety of oseltamivir during the 2009 influenza pandemic.

METHODS

Case reports were obtained from the Roche safety database. The incidence of adverse events (AEs) during the pandemic (1 May 2009 to 31 December 2009) was compared with that beforehand (during previous influenza seasons) for USA and Japan only, as exposure data in other countries were collected inconsistently. Events with significantly higher reporting during the pandemic (lower bound of 95%CI for crude rate ratio >1) were analyzed further.

RESULTS

Global exposure in the pandemic and prepandemic periods was 18.3 and 64.7 million patients, respectively. In USA and Japan, exposure was 15.5 (1382 cases, 2225 events) and 62.0 million (8387 cases, 12,749 events), respectively. AEs with significantly higher reporting during the pandemic were generally consistent with influenza and its complications and/or with the circulation of a novel virus strain. As might be expected in a pandemic, mortality increased (crude rate ratio, 2.83; 95%CI, 2.23-3.59) versus the prepandemic period. Medical review of serious AEs (fatal or non-fatal outcome) found that most were consistent with pre-existing risk factors, underlying disease, and/or progression of influenza or its complications. Analysis of the remainder did not suggest a causal link with oseltamivir. A review of AEs in previously underexposed subpopulations did not support an association with oseltamivir.

CONCLUSIONS

During the first 8 months of the 2009 influenza pandemic, AEs reported in patients exposed to oseltamivir were consistent with the drug's labeled safety profile, underlying medical conditions, or infection with the pandemic virus.

Birth outcomes among women exposed to neuraminidase inhibitors during pregnancy

PURPOSE

To compare birth outcomes between women exposed and unexposed to the antiviral medications oseltamivir or zanamivir during pregnancy.

METHODS

This was an observational cohort study including women who gave birth to singletons in Sweden 2005-2007 and their infants. We obtained information from the national health registers and evaluated risks of low Apgar score, small for gestational age (SGA), low birth weight, preterm delivery, congenital malformations, birth-related death (stillbirth and neonatal death combined), and neonatal morbidity by conditional logistic regression. The unexposed [n = 860] were matched to the exposed [n = 86] by birth year and fetal gender.

RESULTS

A total of 81 women filled a prescription with oseltamivir only, 2 with zanamivir, and 3 with both oseltamivir and zanamivir. Compared with the unexposed infants, the exposed ones had higher risks of late transient hypoglycemia (crude OR = 4.00, 95%CI: 1.26-12.76). There were no statistical increased risks of low Apgar score, congenital malformations, SGA, low birth weight, preterm birth, or birth-related death. Adjusting for maternal age, parity, smoking, and body mass index had minor effects on the results. None of the women exposed to oseltamivir or zanamivir had been admitted to hospital for influenza during their pregnancy.

CONCLUSIONS

Except for an increased risk of late transient hypoglycemia, we found no increased risks of adverse birth outcomes among infants exposed to neuraminidase inhibitors in fetal life compared with the unexposed.