Selected Viral Infections in Pregnancy

Efficacy and effectiveness of maternal influenza vaccination during pregnancy: a review of the evidence

Influenza vaccine is universally recommended for pregnant women during any trimester of pregnancy. In light of this recommendation, a comprehensive literature review was conducted to examine the available evidence regarding influenza vaccine efficacy and effectiveness during pregnancy. A comprehensive Medline search identified potentially relevant articles published between January 1, 1964 and February 1, 2013. Articles were selected that specifically evaluated the efficacy and effectiveness of maternal influenza vaccine in protecting women and infants from influenza infection. These were reviewed with a particular focus on the methods used to confirm influenza infection. Ten of 476 articles met the inclusion criteria. None of the six studies evaluating maternal outcomes were randomized controlled studies using a laboratory-confirmed influenza diagnosis to measure vaccine efficacy. Two studies included reverse-transcriptase polymerase chain reaction confirmation; four relied solely on clinical outcomes. The reported vaccine effectiveness (VE) ranged from -15 to 70 %. Seven studies examined the potential for maternal vaccination to protect infants. Four of these applied some form of laboratory confirmation, with VE ranging from 41 to 91 %. Vaccination against infectious disease is an unparalleled public health success. However, studies to date demonstrate that influenza vaccine provides only moderate protection from influenza infection in pregnant women. This review found broad heterogeneity among studies, with no uniform outcome measured and little data based on laboratory-confirmed influenza, leading to wide-ranging estimates of effectiveness. Rigorously designed studies assessing clearly defined outcomes are needed to support the development of reasoned public health policy about influenza prevention in this population.

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.

Gynecologic and other infections in pregnancy

The treatment of gynecologic and other infections in obstetric patients involves consideration of the physiologic changes of pregnancy, the clinical implications of the infection for the patient as well as the fetus, and the safety of antimicrobials available for therapy. This article highlights the treatment of infections of the vagina, uterus, and urinary tract, with a focus on how therapy changes in obstetric patients. In addition, the emergency department management of other clinically important infections in pregnancy, such as those caused by the human immunodeficiency virus, influenza viruses, methicillin-resistant Staphylococcus aureus, Parvovirus, Listeria, and others is reviewed.

Viral invasion of the amniotic cavity (VIAC) in the midtrimester of pregnancy

INTRODUCTION

The prevalence of viral infections in the amniotic fluid (AF) has not yet been ascertained. The aim of this study was to determine the prevalence of specific viral nucleic acids in the AF and its relationship to pregnancy outcome.

STUDY DESIGN

From a cohort of 847 consecutive women undergoing midtrimester amniocentesis, 729 cases were included in this study after exclusion of documented fetal anomalies, chromosomal abnormalities, unavailability of AF specimens and clinical outcomes. AF specimens were tested by quantitative real-time PCR for the presence of genome sequences of the following viruses: adenoviruses, herpes simplex virus (HSV), varicella zoster virus (VZV), human herpesvirus 6 (HHV6), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), parvovirus B19 and enteroviruses. Viral nucleic acid testing was also performed in maternal blood and cord blood in the population of women in whom AF was positive for viruses and in a control group of 29 women with AF negative for viral nucleic acids. The relationship between the presence of viruses and pregnancy and neonatal outcome was examined. The correlation between the presence of nucleic acids of viruses in the AF and the concentration of the cytokine interleukin-6 (IL-6) and the T cell chemokine CXCL-10 (or IP-10) in AF and maternal blood were analyzed.

RESULTS

Viral genome sequences were found in 16 of 729 (2.2%) AF samples. HHV6 was the most commonly detected virus (7 cases, 1.0%), followed by HCMV (6 cases, 0.8%), parvovirus B19 (2 cases, 0.3%) and EBV (1 case, 0.1%), while HSV, VZV, enteroviruses and adenoviruses were not found in this cohort. Corresponding viral DNA was also detected in maternal blood of six out of seven women with HHV6-positive AF and in the umbilical cord plasma, which was available in one case. In contrast, viral DNA was not detected in maternal blood of women with AF positive for parvovirus B19, HCMV, EBV or of women with AF negative for viruses. HHV6 genome copy number in AF and maternal blood was consistent with genomic integration of viral DNA and genetic infection in all women. There was no significant difference in the AF concentration of IL-6 and IP-10 between patients with and without VIAC. However, for HCMV, there was a significant relationship between viral copy number and IP-10 concentration in maternal blood and AF. The group of women with AF positive for viral DNA delivered at term healthy neonates without complications in 14 out of 16 cases. In one case of HHV6 infection in the AF, the patient developed gestational hypertension at term, and in another case of HHV6 infection in the AF, the patient delivered at 33 weeks after preterm premature rupture of membranes (PPROM).

CONCLUSION

Viral nucleic acids are detectable in 2.2% of AF samples obtained from asymptomatic women in the midtrimester. HHV6 was the most frequently detected virus in AF. Adenoviruses were not detected. Vertical transmission of HHV6 was demonstrated in one case.