Deaths from seasonal influenza among pregnant women in the United States, 1998-2005

Preventing Influenza Virus Infection and Severe Influenza Among Pregnant People and Infants

The landscape of research on the benefits of influenza vaccines and antivirals to protect pregnant persons and infants has increased in recent years, while influenza vaccination rates and antiviral usage have declined. Pregnant people and infants <6 months of age are at increased risk of hospitalization with influenza, making protection of this population essential. Maternal influenza vaccination at any time during pregnancy is the best way to reduce the risk of influenza and severe influenza in both pregnant people and their infants <6 months of age. Influenza antiviral medications for pregnant people and infants are also recommended as early as possible if influenza is confirmed or suspected. This report will update on the current research on the benefits of influenza vaccination during pregnancy and influenza antiviral medication for the pregnant person and infant, current Advisory Committee on Immunization Practices recommendations for influenza vaccination in pregnancy and vaccination coverage rates, current influenza antiviral medication guidance and usage rates in pregnancy and among infants, and future directions for influenza pregnancy research. With over half a century of maternal influenza vaccination in the United States, we have improved protection for pregnant persons and infants against influenza, but we still have room for improvement and optimization with new challenges to overcome following the COVID-19 pandemic. By continuing to fill research gaps and increase vaccination coverage and antiviral usage, there is potential for significant reductions in the domestic and global burden of influenza in pregnant persons and infants.

The Knowledge and Perceptions of Florida Pharmacists in Administering Inactivated Influenza Vaccines to Pregnant Women

BACKGROUND

Influenza vaccine rates in pregnant women remain suboptimal despite the recommendations from healthcare organizations. Though pharmacists can provide immunization services as a result of the standing order, few studies have examined the role of the pharmacist in providing immunization to pregnant women or explored their perspective on their role in providing influenza vaccines among pregnant women.

PURPOSE

This study explored the perceptions and knowledge of Florida pharmacists in administering inactivated influenza vaccines (IIV) to pregnant women.

METHODS

Semi-structured in-depth interviews guided by the theory of planned behavior were conducted with 18 licensed Florida pharmacists, including clinical and retail pharmacists. A thematic analysis was conducted.

RESULTS

The majority of pharmacists (94%) were knowledgeable about the IIV in pregnant women. Participants expressed mixed attitudes, identified barriers and facilitators, and subjective norms influencing vaccine administration in pregnant women. Participants expressed the importance of trust and how that influenced vaccine uptake. Participants also expressed their position not to only provide immunization services but also to counsel and educate patients.

CONCLUSION

There is a need to strengthen immunization services, provided by pharmacists to more individuals, including high-risk groups such as pregnant women.

Knowledge, attitudes, and practices of seasonal influenza vaccination in postpartum women, Honduras

Background

Influenza during pregnancy may cause serious neonatal outcomes including stillbirth, fetal distress, preterm birth, congenital abnormalities, and stunted growth. Pregnant women are the highest priority group for seasonal influenza vaccination, but low coverage has been repeatedly reported in this population. Understanding reasons for and for not receiving the seasonal influenza vaccine is needed to design communication strategies to increase vaccination coverage. This study aimed to describe knowledge, attitudes, and practices (KAP) of seasonal influenza vaccination among women giving birth in public maternity hospitals in Honduras.

Methods

From August 20–October 8, 2018, we conducted a cross-sectional KAP survey regarding seasonal influenza vaccinations to a sample of postpartum women who gave birth in maternity hospitals and clinics from the Ministry of Health of Honduras and Honduran Social Security Institute. We reported frequency distributions for demographics, KAP of influenza vaccine, and vaccination coverage. We used logistic regression to analyze unadjusted and adjusted associations between sociodemographic characteristics and influenza vaccination.

Results

We surveyed 842 postpartum women in 17 healthcare facilities. Of 534 postpartum women with term pregnancy and verified vaccinations, 417 (78.1%; 95% CI: 74.6–81.6%) were vaccinated for influenza. Factors associated with verified influenza vaccination included receipt of vaccination recommendations by a healthcare worker during prenatal check-ups (aOR: 16.46; 95% CI: 9.73–27.85), concurrent chronic disease (aOR: 5.00; 95% CI: 1.25–20.07), and influenza vaccination of other children in the household (aOR: 2.28; 95% CI: 1.19–4.39). The most cited reasons for vaccination were perceived benefits for both mother and infant and easy access. Reasons for non-vaccination were: vaccine was not offered and fear of side effects, harm to the infant, and needles or pain caused by injection.

Conclusion

Influenza vaccination was well received among postpartum women in Honduras. Increasing clinician recommendations for vaccination and assuring the vaccine is readily available to women during prenatal visits may increase vaccination rates.

Seasonal Influenza Vaccine in Pregnant Women: Views and Experiences of Obstetrician-Gynecologists

Background: Seasonal influenza vaccination rates among pregnant women remain well below the Healthy People 2020 target of 80%. Obstetrician-gynecologist (OB/GYN) recommendations are a critical means of encouraging pregnant women to get vaccinated, but there are limited data about their views. Materials and Methods: A nationally representative survey of 506 practicing OB/GYNs was completed between October 26, 2015, and May 8, 2016. Analyses included univariate distributions and comparisons based on age, size of practice, and academic affiliation using all-pairs, dependent t-tests. Results: A majority of OB/GYNs report they "strongly recommend" seasonal influenza vaccination for their pregnant patients in the first (79%) or second and third trimesters (81%). Among those who do not strongly recommend the flu vaccine in the first trimester, many say this is because of their own concerns (28%) or their patients' concerns (44%) about safety. Older OB/GYNs, those in smaller practices, and those without academic affiliation were less likely to recommend the vaccine and more likely to have safety concerns. For example, 72% of those age 60+ strongly recommended the vaccine in the second and third trimester, compared with 86% of those ages 30-44 and 83% of those ages 45-59 (p < 0.05 for all comparisons). Conclusions: OB/GYNs across the country largely support seasonal flu vaccination among pregnant women. Nonetheless, safety is a concern for them and their patients. Outreach to support clinician decisions and conversations with pregnant patients may be most needed among older physicians, those in smaller practices, and those without academic affiliation.

An exploration of midwives' role in the promotion and provision of antenatal influenza immunisation: A mixed methods inquiry

PROBLEM

No South Australian study has previously investigated the role of midwives in the promotion and provision of antenatal influenza immunisation.

BACKGROUND

Influenza acquired in pregnancy can have serious sequalae for both mother and foetus. Recent studies have demonstrated that influenza vaccine in pregnancy is both safe and effective. Despite this, evidence suggests that vaccine uptake in pregnancy is suboptimal in both Australia and worldwide.

AIM

The aim of this study was to investigate the role of midwives in the promotion and provision of antenatal influenza vaccine and, to provide a statistical and thematic description of the barriers and enablers midwives encounter.

METHODS

This mixed method study incorporated a cross sectional on-line survey and in-depth interviews conducted with midwives, employed in urban and regional South Australia.

FINDINGS

Quantitative data were available for 137 midwives and 10 midwives participated in the interviews. Recruitment for the interview phase was through the last question on the survey. Whilst all midwives indicated that education and vaccine promotion were part of their role, immunisation knowledge varied between Registered Nurse/Midwives (RM/RN) 80% and Registered Midwives (RM) 48.90% (p = 0.001). Quantitative data showed that only 43% of midwives felt sufficiently educated to provide the vaccine. Midwives who had received formal immunisation training were more likely to recommend the vaccine 93.7% (p = 0.001). Qualitative data confirmed these results and identified the lack of immunisation education as a barrier to practise.

CONCLUSION

Midwives identified an immunisation knowledge deficit. Midwives who had received immunisation education were more likely to actively promote and provide the vaccine to pregnant women. These findings indicate the need for more immunisation education of midwives in both tertiary and practice settings.

Pregnancy Induces a Steady-State Shift in Alveolar Macrophage M1/M2 Phenotype That Is Associated With a Heightened Severity of Influenza Virus Infection: Mechanistic Insight Using Mouse Models

BACKGROUND

Influenza virus infection during pregnancy is associated with enhanced disease severity. However, the underlying mechanisms are still not fully understood. We hypothesized that normal alveolar macrophage (AM) functions, which are central to maintaining lung immune homeostasis, are altered during pregnancy and that this dysregulation contributes to the increased inflammatory response to influenza virus infection.

METHODS

Time-mated BALB/c mice were infected with a low dose of H1N1 influenza A virus at gestation day 9.5. Inflammatory cells in bronchoalveolar lavage (BAL) fluid were assessed by flow cytometry.

RESULTS

Our findings confirm previous reports of increased severity of influenza virus infection in pregnant mice. The heightened inflammatory response detected in BAL fluid from infected pregnant mice was characterized by neutrophil-rich inflammation with concomitantly reduced numbers of AM, which were slower to return to baseline counts, compared with nonpregnant infected mice. The increased infection severity and inflammatory responses to influenza during pregnancy were associated with a pregnancy-induced shift in AM phenotype at homeostatic baseline, from the M1 (ie, classical activation) state toward the M2 (ie, alternative activation) state, as evidence by increased expression of CD301 and reduced levels of CCR7.

CONCLUSION

These results show that pregnancy is associated with an alternatively activated phenotype of AM before infection, which may contribute to heightened disease severity.

Factors Associated with Antenatal Influenza Vaccination in a Medically Underserved Population

Influenza infection in pregnant women is associated with increased risk of morbidity and mortality. Despite recommendations for all women to receive the seasonal influenza vaccine during pregnancy, vaccination rates among pregnant women in the U.S. have remained around 50%. The objective of this study was to evaluate clinical and demographic factors associated with antenatal influenza vaccination in a medically underserved population of women. We conducted a retrospective cohort study at Grady Memorial Hospital, a large safety-net hospital in Atlanta, Georgia, from July 1, 2016, to June 30, 2018. Demographic and clinical characteristics were abstracted from the electronic medical record. The Kotelchuck index was used to assess prenatal care adequacy. Relative risks and 95% confidence intervals for associations between receipt of influenza vaccine and prenatal care adequacy, demographic characteristics, and clinical characteristics were calculated using multivariable log-binominal models. Among 3723 pregnant women with deliveries, women were primarily non-Hispanic black (68.4%) and had Medicaid as their primary insurance type (87.9%). The overall vaccination rate was 49.8% (1853/3723). Inadequate prenatal care adequacy was associated with a lower antenatal influenza vaccination rate (43.5%), while intermediate and higher levels of prenatal care adequacy were associated with higher vaccination rates (66.9–68.3%). Hispanic ethnicity, non-Hispanic other race/ethnicity, interpreter use for a language other than Spanish, and preexisting diabetes mellitus were associated with higher vaccination coverage in multivariable analyses. Among medically underserved pregnant women, inadequate prenatal care utilization was associated with a lower rate of antenatal influenza vaccination. Socially disadvantaged women may face individual and structural barriers when accessing prenatal care, suggesting that evidenced-based, tailored approaches may be needed to improve prenatal care utilization and antenatal influenza vaccination rates.

Maternal tetanus, diphtheria, and acellular pertussis (Tdap) and influenza immunization: an overview

BACKGROUND

Maternal tetanus, diphtheria, and acellular pertussis (Tdap) and influenza immunization for women during pregnancy (the so-called "maternal immunization") has been introduced in several countries, and recently also in Italy, to protect mother and fetus during pregnancy, infant in his first months of life and mother during postpartum period. However, very low vaccination coverage rates have been reached due to several variables.

METHODS

A literature search was conducted on PubMed and Embase, including any experimental or observational studies, to assesses existing evidence on the effectiveness, efficacy, safety and optimal timing of administration of Tdap and influenza immunization in pregnancy for mothers and their infants. The search was finalized in August 2019.

RESULTS

Reviewing the literature, we identified only a few studies that, among several maternal and infant outcomes, found sporadic significant associations with maternal influenza immunization and even less with Tdap immunization. Moreover, most of the authors of these studies explained these findings as a result of residual confounding effect. The effectiveness of maternal influenza immunization is more complicated to prove than the effectiveness of Tdap immunization because of several reasons. Not all nations recommend and offer vaccines in the same weeks of pregnancy and this one manifests the complexity in defining the best timing for Tdap or influenza immunization.

CONCLUSIONS

The safety of maternal Tdap or influenza immunization is supported by the evidence so far, however, regular surveillance should be maintained, especially with regard to the influenza vaccine that changes in formulation each year. There is a need to optimize the timing of vaccination in pregnancy and to have a national system of detection of maternal immunization in each country.

Predictors of tetanus, diphtheria, acellular pertussis and influenza vaccination during pregnancy among full-term deliveries in a medically underserved population

OBJECTIVE

To evaluate predictors of vaccination among women who received tetanus, diphtheria, and acellular pertussis vaccination (Tdap), influenza vaccination, and Tdap and influenza vaccinations.

STUDY DESIGN

In a retrospective cohort study of all full-term (≥37 weeks gestation) deliveries between July 1, 2016 and June 30, 2018 at a single, safety-net institution, we used multinomial logistic regression models to compare predictors of vaccination among women who received Tdap only, influenza only, and both Tdap and influenza vaccines.

RESULTS

Among 3132 full-term deliveries, women were primarily non-Hispanic black (67.5%), between the ages of 21-34 (65.3%), and multiparous (76.0%). The rates of only influenza or Tdap vaccination were 10.3% and 21.6%, respectively; 43.3% of women received both vaccines, and 24.9% of women did not receive either vaccine. In the adjusted models, Hispanic ethnicity was positively associated with receipt of all types of vaccination and non-Spanish language interpreter use was positively associated with receipt of Tdap vaccination and Tdap and influenza vaccination. A parity of greater than three and inadequate and unknown prenatal care adequacy were negative predictors of all types of vaccination. Pre-existing hypertension was negatively associated with Tdap vaccination, and HIV-positive status was negatively associated with influenza vaccination and Tdap and influenza vaccination.

CONCLUSION

Compared to the national rate of both Tdap and influenza vaccination (32.8%), a higher proportion of women received both vaccines in our study population. Vaccine uptake may be affected by race/ethnicity, use of interpreter services, parity, pre-existing comorbidities, and prenatal care adequacy. The lower rate of influenza vaccination compared to Tdap vaccination suggests that other factors, such as vaccine hesitancy and mistrust, may be differentially impacting influenza vaccination uptake in our predominantly minority population. Future provider and public health approaches to vaccine promotion should incorporate culturally appropriate strategies that address vaccine-related beliefs and misconceptions.

Maternal Mortality in the United States: A Review of Contemporary Data and Their Limitations

This article provides a review of maternal mortality data and their limitations in the United States. National maternal mortality data, which rely heavily on vital statistics, document that the risk of death from pregnancy-related causes has not declined for >25 years and that striking racial disparities persist. State-based maternal mortality reviews, functional in many states, obtain detailed information on medical and nonmedical factors contributing to maternal deaths. Without this detailed knowledge from state-level data and without addressing recognized quality problems with vital statistics data at the national-level, we will have difficulty understanding maternal death trends and preventing future such deaths.

Estimating Vaccine Effectiveness Against Hospitalized Influenza During Pregnancy: Multicountry Protocol for a Retrospective Cohort Study

Background

Although pregnant women are believed to have elevated risks of severe influenza infection and are targeted for influenza vaccination, no study to date has examined influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza-associated hospitalizations during pregnancy, primarily because this outcome poses many methodological challenges.

Objective

The Pregnancy Influenza Vaccine Effectiveness Network (PREVENT) was formed in 2016 as an international collaboration with the Centers for Disease Control and Prevention; Abt Associates; and study sites in Australia, Canada, Israel, and the United States. The primary goal of this collaboration is to estimate IVE in preventing acute respiratory or febrile illness (ARFI) hospitalizations associated with laboratory-confirmed influenza virus infection during pregnancy. Secondary aims include (1) describing the incidence, clinical course, and severity of influenza-associated ARFI hospitalization during pregnancy; (2) comparing the characteristics of ARFI-hospitalized pregnant women who were tested for influenza with those who were not tested; (3) describing influenza vaccination coverage in pregnant women; and (4) comparing birth outcomes among women with laboratory-confirmed influenza-associated hospitalization versus other noninfluenza ARFI hospitalizations.

Methods

For an initial assessment of IVE, sites identified a retrospective cohort of pregnant women aged from 18 to 50 years whose pregnancies overlapped with local influenza seasons from 2010 to 2016. Pregnancies were defined as those that ended in a live birth or stillbirth of at least 20 weeks gestation. The analytic sample for the primary IVE analysis was restricted to pregnant women who were hospitalized for ARFI during site-specific influenza seasons and clinically tested for influenza virus infection using real-time reverse transcription polymerase chain reaction.

Results

We identified approximately 2 million women whose pregnancies overlapped with influenza seasons; 550,344 had at least one hospitalization during this time. After restricting to women who were hospitalized for ARFI and tested for influenza, the IVE analytic sample included 1005 women.

Conclusions

In addition to addressing the primary question about the effectiveness of influenza vaccination, PREVENT data will address other important knowledge gaps including understanding the incidence, clinical course, and severity of influenza-related hospitalizations during pregnancy. The data infrastructure and international partnerships created for these analyses may be useful and informative for future influenza studies.

International Registered Report Identifier (IRRID)

DERR1-10.2196/11333

Identifying ways to increase seasonal influenza vaccine uptake among pregnant women in China: A qualitative investigation of pregnant women and their obstetricians

BACKGROUND

Pregnant women are at higher risk for complications from influenza infection. Nevertheless, seasonal influenza vaccination among pregnant women in China is low. A better understanding of perceptions of pregnant women and their physicians, and factors influencing decisions about receiving seasonal influenza vaccine could be used to develop effective strategies for improving seasonal influenza vaccine uptake during pregnancy.

METHODS

We recruited pregnant women from 9 hospitals located in 5 cities across China to participate in focus group interviews. Obstetricians from the same hospitals were recruited for one on one in-depth interviews. We collected information about perceptions of barriers and motivating factors for utilizing seasonal influenza vaccine during pregnancy. We systematically analyzed the information using qualitative methods.

RESULTS

We conducted 18 focus groups with 108 pregnant women and interviewed 18 obstetricians. Awareness about the use of influenza vaccine during pregnancy was minimal in both subject groups. None of the pregnant women had received influenza vaccine during pregnancy and none of the obstetricians had recommended influenza vaccine for their patients. Both groups noted insufficient knowledge about influenza infection and benefits of the vaccine, concerns about vaccine safety, and lack of local data related to vaccine use in Chinese pregnant women. Obstetricians cited the lack of a national policy as a major barrier to recommending seasonal influenza vaccine to pregnant women. Pregnant women cited not receiving a recommendation for vaccination from healthcare workers as an additional barrier.

CONCLUSION

Our findings highlight the immediate need to increase awareness and knowledge about the risks of influenza infection and the benefits and safety of seasonal influenza vaccination among both pregnant women and obstetricians in China. Obstetricians interviewed stated that the development and implementation of a national policy prioritizing pregnant women for seasonal influenza vaccination would facilitate their willingness to recommend seasonal influenza vaccine to pregnant women.

Impact of maternal vaccination timing and influenza virus circulation on birth outcomes in rural Nepal

OBJECTIVE

To describe the effect of maternal vaccination on birth outcomes in rural Nepal, modified by timing of vaccination in pregnancy and influenza virus activity.

METHODS

A secondary analysis was conducted using data from two annual cohorts of a randomized controlled trial. A total of 3693 pregnant women from Sarlahi District were enrolled between April 25, 2011, and September 9, 2013. All participants were aged 15-40 years and received a trivalent inactivated influenza vaccine or placebo. The outcome measures included birth weight, pregnancy length, low birth weight (<2500 g), preterm birth, and small-for-gestational-age birth.

RESULTS

Data were available on birth weight for 2741 births and on pregnancy length for 3623 births. Maternal vaccination increased mean birthweight by 42 g (95% confidence interval [CI] 8-76). The magnitude of this increase varied by season but was greatest among pregnancies with high influenza virus circulation during the third trimester. Birth weight increased by 111 g (95% CI -51 to 273) when 75%-100% of a pregnancy's third trimester had high influenza virus circulation versus 38 g (95% CI -6 to 81) when 0%-25% of a pregnancy's third trimester had high influenza virus circulation. However, these results were nonsignificant.

CONCLUSION

Seasonal maternal influenza vaccination in rural Nepal increased birth weight; the magnitude appeared larger during periods of high influenza virus circulation. CLINICALTRIALS.GOV: NCT01034254.

A population-based analysis of predictors of influenza vaccination uptake in pregnant women: The effect of gestational and calendar time

Pregnant women are vaccinated against influenza less frequently than other high-risk groups. To design effective vaccination strategies, we must understand how decisions regarding vaccination may vary by trimester and over vaccination campaigns. We used a Cox model indexed by calendar time to estimate the effect of gestational trimester and other factors on vaccination uptake in a large cohort of pregnant women in Catalonia (Spain) during 2008-09 to 2012-13 influenza vaccination campaigns. We analyzed 247,316 pregnancies. Vaccination coverage was 3.7%, 5.2%, 4.8%, 5.6% and 4.6% from 2008-09 to 2012-13 seasonal vaccination campaigns and 8.3% for the 2009 pandemic vaccination campaign. Pregnant women previously vaccinated had higher uptake than women not previously vaccinated and the hazard ratios (HRs) comparing these 2 groups decreased from 10, the first day of seasonal campaigns, to 1.3 the last day. During the pandemic campaign, HRs decreased over the course of the campaign from 8.6 to 1.9. Women in second and third trimester had higher uptake than women in first trimester, with HR=2.8 and 2.3, respectively, at the start of seasonal campaigns. Influenza vaccination coverage among this cohort of pregnant women was alarmingly low. Our analysis reveals that gestational and calendar time have distinct and interacting effects on vaccination uptake; women in their second trimester and third trimester and previously vaccinated were more prone to be vaccinated, but this effect wanes as the influenza season progresses.

Incidence of influenza virus infection among pregnant women: a systematic review

BACKGROUND

The World Health Organization (WHO) considers pregnant women to be a risk group for severe influenza disease. We conducted a systematic review to evaluate influenza disease incidence in pregnant women in order to inform estimates of influenza vaccine impact for low-resource countries.

METHODS

We performed electronic literature searches, targeting studies on the following outcomes in pregnant women: attack rate, hospitalization rate, intensive care unit admission rate, mortality rate, and disability-adjusted life years lost. Only original studies published in peer-reviewed journals that had laboratory confirmation for influenza virus infection and included population-based incidence rates with denominator data were included. We summarized study characteristics in descriptive tables and outcome-specific Forest plots. We generated summary incidence rates using random effects models and assessed statistical heterogeneity by visual examination of Forest plots, and by χ 2 and I2 tests.

RESULTS

We identified 1543 articles, of which nine articles met the study inclusion criteria. Five were case series, three were cohort studies, and one was a randomized controlled trial. Eight studies were from high-income countries, and one was from an upper middle-income country. Six studies reported results for pandemic influenza, and three reported seasonal influenza. Statistical heterogeneity was high for all outcomes, and methodologies and duration of surveillance varied considerably among studies; therefore, we did not perform meta-analyses.

CONCLUSIONS

Study quality was very low according to GRADE criteria. More data on influenza disease incidence in pregnant women, particularly in low- and middle-income countries and for seasonal influenza disease, are needed to inform public health decision-making.

Risks associated with viral infections during pregnancy

Despite the prevalence of viral infections in the American population, we still have a limited understanding of how they affect pregnancy and fetal development. Viruses can gain access to the decidua and placenta by ascending from the lower reproductive tract or via hematogenous transmission. Viral tropism for the decidua and placenta is then dependent on viral entry receptor expression in these tissues as well as on the maternal immune response to the virus. These factors vary by cell type and gestational age and can be affected by changes to the in utero environment and maternal immunity. Some viruses can directly infect the fetus at specific times during gestation, while some only infect the placenta. Both scenarios can result in severe birth defects or pregnancy loss. Systemic maternal viral infections can also affect the pregnancy, and these can be especially dangerous, because pregnant women suffer higher virus-associated morbidity and mortality than do nonpregnant counterparts. In this Review, we discuss the potential contributions of maternal, placental, and fetal viral infection to pregnancy outcome, fetal development, and maternal well-being.

Management of Infection for the Obstetrician/Gynecologist

Pregnant women have an increased morbidity and mortality for certain illnesses owing to the physiologic and immunologic changes in pregnancy. Certain infections are common during pregnancy, including urinary tract infections and pneumonia. Others are uncommon, but yield increased severity, including influenza. Human immunodeficiency virus, although it does not increase in pathogenesis during pregnancy, requires specific attention and management in the context of pregnancy.

Do Thai Physicians Recommend Seasonal Influenza Vaccines to Pregnant Women? A Cross-Sectional Survey of Physicians' Perspectives and Practices in Thailand

BACKGROUND

Physicians play a major role in influencing acceptance and uptake of vaccines. However, little is known about physicians' perspectives on influenza vaccination of pregnant women in Thailand, for whom vaccine coverage is estimated at <1%.

METHOD

In 2013, a self-administered questionnaire on physicians' perceptions, attitudes and practices related to influenza vaccination for pregnant women was distributed to 1,134 hospitals with an antenatal care clinic (ANC) in Thailand. At each hospital, one physician working at the ANC completed the survey. Predictors of routine recommendation of influenza vaccine were analyzed utilizing log-binomial regression.

RESULTS

A total of 580 (51%) complete responses were received from physicians practicing at ANCs. A favorable attitude towards vaccination was expressed by 436 (75%) physicians, however only 142 (25%) reported routinely recommending influenza vaccine to pregnant women in their current practice. Physicians were more likely to recommend influenza vaccine routinely when they had more than three years of practice (prevalence ratio [PR] 1.9, 95% CI 1.2-2.3), had treated pregnant women for influenza (PR 1.8, 95% CI 1.3-2.7), perceived the influenza vaccine to be effective (moderate level: PR 1.6, 95% CI 1.1-2.4; high level: PR 1.9, 95% CI 1.3-2.9) and were aware of the Ministry of Public Health's (MOPH) recommendation of influenza vaccination in pregnancy (PR 1.3, 95% CI 1.1-1.7). Vaccine not being available, perception that policy was ambiguous and lack of awareness of MOPH recommendations were the most commonly cited barriers to routine recommendation of influenza vaccine.

CONCLUSION

Despite a national policy to vaccinate pregnant women for influenza, only 25% of Thai physicians working in ANCs routinely recommend vaccination. Strategies are needed to increase vaccine availability and free vaccine services, address clinician concerns over vaccine effectiveness and expand healthcare provider awareness of MOPH recommendations.

Brief education to promote maternal influenza vaccine uptake: A randomized controlled trial

BACKGROUND

Although pregnant women are the highest priority group for seasonal influenza vaccination, maternal influenza vaccination rates remain suboptimal. The purpose of this study was to evaluate the effect of a brief education intervention on maternal influenza vaccine uptake.

METHODS

During the 2013-14 and 2014-15 influenza seasons, we recruited 321 pregnant women from the antenatal clinics of 4 out of 8 public hospitals in Hong Kong with obstetric services. Hospitals were geographically dispersed and provided services to pregnant women with variable socioeconomic backgrounds. Participants were randomized to receive either standard antenatal care or brief one-to-one education. Participants received telephone follow-up at 2 weeks postpartum. The primary study outcome was self-reported receipt of influenza vaccination during pregnancy. The secondary outcomes were the proportion of participants who initiated discussion about influenza vaccination with a health care professional and the proportion of participants who attempted to get vaccinated.

RESULTS

Compared with participants who received standard care, the vaccination rate was higher among participants who received brief education (21.1% vs. 10%; p=0.006). More participants in the education group initiated discussion about influenza vaccination with their HCP (19.9% vs. 13.1%; p=0.10), but the difference was not statistically significant. Of participants who did not receive the influenza vaccine (n=271), 45 attempted to get vaccinated. A significantly higher proportion of participants who attempted to get vaccinated were in the intervention group (82.2% vs. 17.8%; p<0.001). If participants who had attempted vaccination had received the vaccine, vaccination rates would have been substantially higher (44.1% vs. 15%; p<0.001). Twenty-six participants were advised against influenza vaccination by a healthcare professional, including general practitioners, obstetricians, and nurses.

CONCLUSION

Although brief education was effective in improving vaccination uptake among pregnant women, overall vaccination rates remain suboptimal. Multicomponent approaches, including positive vaccination recommendations by healthcare professionals, are needed to promote maternal influenza vaccination.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov (NCT01772901).

Influenza vaccination of pregnant women protects them over two consecutive influenza seasons in a randomized controlled trial

BACKGROUND

We assessed the persistence of hemagglutinin inhibition (HAI) antibodies and the vaccine efficacy (VE) of trivalent inactivated influenza vaccine (IIV3) following vaccination of a cohort of pregnant South African women during a second influenza season.

METHODS

A cohort of women who participated in a randomized placebo-controlled trial on the safety, immunogenicity and efficacy of IIV3 in 2011 had HAI titers measured in 2012 and were monitored for influenza illness until the end of 2012.

RESULTS

The proportion of women with HAI titers ≥1:40 was significantly greater in vaccinees (63%) compared to placebo-recipients (22%; p < 0.001). VE in 2012 was 63.8% (95% confidence interval [95%CI]: -33.7%, 90.2%); combined VE for 2011 and 2012 was 58.3% (95%CI: 0.2%, 82.6%).

CONCLUSION

The majority of women who received IIV3 during pregnancy had HAI titers above the putative threshold for protection against influenza illness one year after vaccination and showed a trend towards protection against influenza disease.

Maternal vaccination for the prevention of influenza: current status and hopes for the future

Influenza is an important cause of morbidity and mortality among pregnant women and young infants, and influenza infection during pregnancy has also been associated with adverse obstetric and birth outcomes. There is substantial evidence - from randomized trials and observational studies - that maternal influenza immunization can protect pregnant women and their infants from influenza disease. In addition, there is compelling observational evidence that prevention of influenza in pregnant women can also protect against certain adverse pregnancy outcomes, including stillbirth and preterm birth. In this article we will review and evaluate the literature on both the burden of influenza disease in pregnant women and infants, as well as the multiple potential benefits of maternal influenza immunization for mother, fetus, and infant. We will also review key clinical aspects of maternal influenza immunization, as well as identify remaining knowledge gaps, and discuss avenues for future investigation.

Interventions to increase the uptake of seasonal influenza vaccination among pregnant women: A systematic review

BACKGROUND

Pregnant women and their infants under 6 months of age infected with influenza have a high risk of serious morbidity and mortality. Influenza vaccine during pregnancy offers 3-for-1 benefits to pregnant women, fetuses and newborn infants. Current vaccination uptake rates during pregnancy, however, are often lower than other high-risk groups and the general population.

METHODS

We systematically reviewed evidence on the effectiveness of interventions to improve influenza vaccination coverage in pregnant women. Risk differences (RDs) were calculated from the included studies.

RESULTS

Eleven studies were included in the review, of which four were randomized controlled trials (RCTs). Three cohort studies assessed provider-focused interventions while four RCTs and one cohort study evaluated pregnant women-focused interventions. Two cohort studies and a prospective intervention study assessed the effectiveness of bundled interventions. No study solely assessed the effectiveness of interventions to enhance access to influenza vaccination. One moderate quality RCT showed that an influenza pamphlet, with or without a verbalized benefit statement, improved the vaccination rate (RD=0.26; RD=0.39). The other reviewed RCTs showed discordant results, with RDs ranging from -0.15 to 0.03. Although all observational studies significantly improved vaccination rates (RDs ranged from 0.03 to 0.44), the quality of the evidence varied.

CONCLUSIONS

There is a lack of effective interventions to increase the influenza vaccination rate in pregnant women. Based on the existing research, we recommend that clinicians provide influenza pamphlets to pregnant women with a verbalized statement about the benefits of influenza vaccine to newborns. Further high-quality RCTs are needed to develop successful maternal influenza vaccination programs. Increased clarity in reporting the content of interventions would help to improve the comparability and generalizability of the published studies.

Pregnancy-Related Mortality Resulting From Influenza in the United States During the 2009-2010 Pandemic

OBJECTIVE

To estimate the burden of pregnancy-related mortality resulting from influenza A (H1N1)pdm09 virus infection during the 2009-2010 pandemic influenza season.

METHODS

Data from the Centers for Disease Control and Prevention's Pregnancy Mortality Surveillance System were used to identify women whose death during or shortly after pregnancy was attributed or likely attributed to the influenza A (H1N1)pdm09 virus from April 15, 2009, through June 30, 2010. We report the characteristics of these women and enumerate cases resulting in death as the pandemic began, peaked, and resolved.

RESULTS

During the pandemic season, we identified 915 pregnancy-related deaths and 4,911,297 live births. Seventy-five (8.2%) women died as a result of confirmed influenza A (H1N1)pdm09 infection deaths and 34 (3.7%) women as a result of possible influenza A (H1N1)pdm09 infection deaths. The pregnancy-related mortality ratio for confirmed and possible (combined) influenza A (H1N1)pdm09 infection deaths was 2.2 per 100,000 live births. Most deaths occurred during the 2009 calendar year with the peak of the distribution of deaths over time occurring in October 2009.

CONCLUSION

Twelve percent of pregnancy-related deaths were attributed to confirmed or possible influenza A (H1N1)pdm09 infection during the 2009-2010 pandemic season. Because prediction of pandemics is difficult, planning for prevention of influenza and care for those women affected are critical for preventing associated severe maternal morbidity and mortality.

LEVEL OF EVIDENCE

III.

Maternal Morbidity and Mortality: Identifying Opportunities to Improve Clinical Outcomes

A better understanding of why women die during pregnancy, childbirth, or postpartum offers valuable insight into strategies aimed at preventing maternal deaths and arresting the progression in the severity of a complication. The rate of severe maternal morbidity and maternal mortality in the United States has been trending upward in recent years and has garnered national attention with concentration on bolstering reviews of maternal deaths and implementing patient safety initiatives. The obstetric nurse is in a unique position to improve maternal outcomes through the anticipation, recognition, and communication of the early warning signs of impending deterioration in maternal condition. Presented in the context of the conceptual model of Stephen Covey's Circle of Influence, the professional nurse can proactively influence maternal outcomes directly, with actions defined by the scope of professional nursing practice or indirectly through professional interactions with others. Advancing one's education, knowledge, and technical skills broadens the influential capacity.

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).

Pregnant women's attitudes toward influenza vaccination while breastfeeding

OBJECTIVE

The goal of this study was to assess the concerns pregnant women have about influenza vaccination while breastfeeding and to determine if having these concerns represents a barrier to vaccination uptake.

METHODS

The Vaccines and Medications in Pregnancy Surveillance System (VAMPSS) conducted a prospective cohort study in the US and Canada of influenza vaccine safety among pregnant women, oversampling vaccinated women. Data for the present paper are from an additional cross-sectional telephone survey completed during the 2010-2011 and 2012-2013 influenza seasons.

RESULTS

We surveyed 431 pregnant women about their attitudes regarding influenza vaccination while breastfeeding. Almost half of the participants identified one or two concerns and 4% reported three or more concerns. About one quarter reported that they would be unlikely to have an influenza vaccination while breastfeeding. In the multivariate model, those reporting 1-2 concerns (OR = 0.16, 95% CI 0.09-0.28) and those reported 3 or more concerns (OR = 0.07, 95% CI 0.02-0.22) had lower odds of being likely to vaccinate.

CONCLUSIONS

Pregnant women and postpartum women who are breastfeeding could benefit from receiving information and recommendations specific to vaccination from their healthcare providers, with a focus on discussing known risks and benefits to the baby's health.

Respiratory disease in pregnancy

Many physiological and anatomical changes of pregnancy affect the respiratory system. These changes often affect the presentation and management of the various respiratory illnesses in pregnancy. This article focuses on several important respiratory issues in pregnancy. The management of asthma, one of the most common chronic illnesses in pregnancy, remains largely unchanged compared to the nonpregnant state. Infectious respiratory illness, including pneumonia and tuberculosis, are similarly managed in pregnancy with antibiotics, although special attention may be needed for antibiotic choices with more pregnancy safety data. When mechanical ventilation is necessary, consideration should be given to the maternal hemodynamics of pregnancy and fetal oxygenation. Maintaining maternal oxygen saturation above 95% is recommended to sustain optimal fetal oxygenation. Cigarette smoking has known risks in pregnancy, and current practice guidelines recommend offering cognitive and pharmacologic interventions to pregnant women to assist in smoking cessation.

Increasing uptake of influenza vaccine by pregnant women post H1N1 pandemic: a longitudinal study in Melbourne, Australia, 2010 to 2014

BACKGROUND

A Melbourne (Australia) university affiliated, tertiary obstetric hospital provides lay and professional education about influenza vaccine in pregnancy annually each March, early in the local influenza season. Responding to a 2011 survey of new mothers' opinions, the hospital made influenza vaccine freely available in antenatal clinics from 2012. We wished to determine influenza vaccination uptake during pregnancy with these strategies 5 years after 2009 H1N1.

METHODS

Face to face interviews based on US Center for Disease Control and Prevention Pregnancy Risk Assessment Monitoring System with new mothers in postnatal wards each July, 2010 to 2014. We calculated recalled influenza vaccine uptake each year and assessed trends with chi square tests, and logistic regression.

RESULTS

We recorded 1086 interviews. Influenza vaccination during pregnancy increased by 6% per year (95% confidence interval 4 to 8%): from 29.6% in 2010 to 51.3% in 2014 (p < 0.001). Lack of discussion from maternity caregivers was a persistent reason for non-vaccination, recalled by 1 in 2 non-vaccinated women. Survey respondents preferred face to face consultations with doctors and midwives, internet and text messaging as information sources about influenza vaccination. Survey responses indicate messages about vaccine safety in pregnancy and infant benefits are increasingly being heeded. However, there was progressively lower awareness of maternal benefits of influenza vaccination, especially for women with risk factors for severe disease.

CONCLUSIONS

We observed improving influenza vaccination during pregnancy. There is potential to integrate technology such as text message or internet with antenatal consultations to increase vaccination coverage further.

Technical guidelines for the application of seasonal influenza vaccine in China (2014-2015)

Influenza, caused by the influenza virus, is a respiratory infectious disease that can severely affect human health. Influenza viruses undergo frequent antigenic changes, thus could spread quickly. Influenza causes seasonal epidemics and outbreaks in public gatherings such as schools, kindergartens, and nursing homes. Certain populations are at risk for severe illness from influenza, including pregnant women, young children, the elderly, and people in any ages with certain chronic diseases.

CDC Pregnancy Flu Line: monitoring severe illness among pregnant women with influenza

The Centers for Disease Control and Prevention implemented the Pregnancy Flu Line (PFL) during the influenza A(H1N1)pdm09 (pH1N1) pandemic and continued operation through the 2010-2011 influenza season to collect reports of intensive care unit (ICU) admissions and deaths among pregnant women with influenza. The system documented the severe impact of influenza on pregnant women during both seasons with 181 ICU/survivals and 37 deaths reported during the 2009 fall pandemic wave and 69 ICU/survivals and ten deaths reported in the subsequent influenza season (2010-2011). A health department survey suggests PFL participants perceived public health benefits and minimum time burdens.

Maternal vaccination: moving the science forward

BACKGROUND

Infections remain one of the leading causes of morbidity in pregnant women and newborns, with vaccine-preventable infections contributing significantly to the burden of disease. In the past decade, maternal vaccination has emerged as a promising public health strategy to prevent and combat maternal, fetal and neonatal infections. Despite a number of universally recommended maternal vaccines, the development and evaluation of safe and effective maternal vaccines and their wide acceptance are hampered by the lack of thorough understanding of the efficacy and safety in the pregnant women and the offspring.

METHODS

An outline was synthesized based on the current status and major gaps in the knowledge of maternal vaccination. A systematic literature search in PUBMED was undertaken using the key words in each section title of the outline to retrieve articles relevant to pregnancy. Articles cited were selected based on relevance and quality. On the basis of the reviewed information, a perspective on the future directions of maternal vaccination research was formulated.

RESULTS

Maternal vaccination can generate active immune protection in the mother and elicit systemic immunoglobulin G (IgG) and mucosal IgG, IgA and IgM responses to confer neonatal protection. The maternal immune system undergoes significant modulation during pregnancy, which influences responsiveness to vaccines. Significant gaps exist in our knowledge of the efficacy and safety of maternal vaccines, and no maternal vaccines against a large number of old and emerging pathogens are available. Public acceptance of maternal vaccination has been low.

CONCLUSIONS

To tackle the scientific challenges of maternal vaccination and to provide the public with informed vaccination choices, scientists and clinicians in different disciplines must work closely and have a mechanistic understanding of the systemic, reproductive and mammary mucosal immune responses to vaccines. The use of animal models should be coupled with human studies in an iterative manner for maternal vaccine experimentation, evaluation and optimization. Systems biology approaches should be adopted to improve the speed, accuracy and safety of maternal vaccine targeting.

Determinants of uptake of influenza vaccination among pregnant women - a systematic review

BACKGROUND

Pregnant women have the highest priority for seasonal influenza vaccine. However, suboptimal coverage has been repeatedly noted in this population. To improve vaccine uptake, reviewing the determinants of vaccination is of increasing importance.

METHODS

A detailed literature search was performed up to November 30, 2013 to retrieve articles related to uptake of influenza vaccination during pregnancy.

RESULTS

Forty-five research papers were included in the review. Twenty-one studies assessed the coverage of seasonal influenza vaccination, 13 studies assessed coverage of A/H1N1 pandemic vaccination and 11 studies assessed both. Vaccination uptake ranged from 1.7% to 88.4% for seasonal influenza, and from 6.2% to 85.7% for A/H1N1 pandemic influenza. Many pregnant women were unaware that they were at high risk for influenza and its complications during pregnancy. They were also more likely to underestimate the threat of influenza to themselves and their fetus. Moreover, they had substantial concerns about the safety and efficacy of the influenza vaccine during pregnancy. Negative media reports contributed to the perception that influenza vaccination during pregnancy was risky and could result in adverse pregnancy outcomes. Although health care providers' (HCPs) recommendations were consistently associated with vaccine uptake, most did not recommend the vaccine to their pregnant clients.

CONCLUSIONS

Influenza vaccination uptake among pregnant women is suboptimal and HCPs rarely recommend it. Positive vaccination recommendations from HCPs as well as direct access to the vaccine would likely substantially improve vaccination acceptance.

Influenza and endemic viral pneumonia

Viruses are a common and important cause of severe community-acquired pneumonia, and may lead to severe respiratory disease and admission to the intensive care unit. Influenza is the most common virus associated with severe viral pneumonia, although other important causes include respiratory syncytial virus, adenovirus, metapneumonia virus, and coronaviruses. Viral pneumonias tend to have a seasonal predilection and are often preceded by a typical viral prodrome. This article focuses on severe influenza pneumonia, including the 2009 H1N1 pandemic, and briefly discusses other causes of severe respiratory disease of viral etiology.

Maintaining the momentum: key factors influencing acceptance of influenza vaccination among pregnant women following the H1N1 pandemic

This survey study compared pre- and post-pandemic knowledge, attitudes, beliefs, and intended behaviors of pregnant women regarding influenza vaccination (seasonal and/or pandemic) during pregnancy in order to determine key factors influencing their decision to adhere to influenza vaccine recommendations. Only 36% of 662 pre-pandemic respondents knew that influenza was more severe in pregnant women, compared to 62% of the 159 post-pandemic respondents. Of the pre-pandemic respondents, 41% agreed or strongly agreed that that it was safer to wait until after the first 3 months to receive the seasonal influenza vaccine, whereas 23% of the post-pandemic cohort agreed or strongly agreed; 32% of pre-pandemic participants compared to 11% of post-pandemic respondents felt it was best to avoid all vaccines while pregnant. Despite 61% of the pre-pandemic cohort stating that they would have the vaccine while pregnant if their doctor recommended it and 54% citing their doctor/nurse as their primary source of vaccine information, only 20% said their doctor discussed influenza vaccination during their pregnancy, compared to 77% of the post-pandemic respondents who reported having this conversation. Women whose doctors discussed influenza vaccine during pregnancy had higher overall knowledge scores (P<0.0001; P=0.005) and were more likely to believe the vaccine is safe in all stages of pregnancy (P<0.0001; P=0.001) than those whose doctors did not discuss influenza vaccination. The 2009 H1N1 pandemic experience appeared to change attitudes and behaviours of health care providers and their pregnant patients toward influenza vaccination.

Effect of influenza vaccination in the first trimester of pregnancy

OBJECTIVE

To estimate the effect of first-trimester influenza vaccination on fetal and neonatal outcomes.

METHODS

This was a retrospective cohort study examining delivery and neonatal outcomes after antepartum exposure to the seasonal trivalent inactive influenza vaccine. Data were collected and entered into an established computerized database. Outcomes by trimester of vaccination were then compared with women who did not receive the vaccine.

RESULTS

During the 5-year study period, 10,225 women received the seasonal influenza vaccine antepartum; 8,690 of these delivered at our institution, 439 in the first trimester and 8,251 in the second and third trimesters. Women vaccinated antepartum were significantly older with higher parity than women who declined vaccination. Neonates born to mothers receiving the vaccine in any trimester did not have an increase in major malformations regardless of trimester of vaccination (2% regardless of vaccination group, P=.9). Stillbirth (0.3% compared with 0.6%, P=.006), neonatal death (0.2% compared with 0.4%, P=.01), and premature delivery (5% compared with 6%, P=.004) were significantly decreased in the vaccinated group.

CONCLUSION

Influenza vaccination in the first trimester was not associated with an increase in major malformation rates and was associated with a decrease in the overall stillbirth rate. This information will aid in counseling women regarding the safety of influenza vaccination in the first trimester.

Severe sepsis and septic shock in pregnancy

Pregnancies complicated by severe sepsis and septic shock are associated with increased rates of preterm labor, fetal infection, and preterm delivery. Sepsis onset in pregnancy can be insidious, and patients may appear deceptively well before rapidly deteriorating with the development of septic shock, multiple organ dysfunction syndrome, or death. The outcome and survivability in severe sepsis and septic shock in pregnancy are improved with early detection, prompt recognition of the source of infection, and targeted therapy. This improvement can be achieved by formulating a stepwise approach that consists of early provision of time-sensitive interventions such as: aggressive hydration (20 mL/kg of normal saline over the first hour), initiation of appropriate empiric intravenous antibiotics (gentamicin, clindamycin, and penicillin) within 1 hour of diagnosis, central hemodynamic monitoring, and the involvement of infectious disease specialists and critical care specialists familiar with the physiologic changes in pregnancy. Thorough physical examination and imaging techniques or empiric exploratory laparotomy are suggested to identify the septic source. Even with appropriate antibiotic therapy, patients may continue to deteriorate unless septic foci (ie, abscess, necrotic tissue) are surgically excised. The decision for delivery in the setting of antepartum severe sepsis or septic shock can be challenging but must be based on gestational age, maternal status, and fetal status. The natural inclination is to proceed with emergent delivery for a concerning fetal status, but it is imperative to stabilize the mother first, because in doing so the fetal status will likewise improve. Aggressive [corrected] treatment of sepsis can be expected to reduce the progression to severe sepsis and septic shock and prevention strategies can include preoperative skin preparations and prophylactic antibiotic therapy as well as appropriate immunizations.

A large, population-based study of 2009 pandemic Influenza A virus subtype H1N1 infection diagnosis during pregnancy and outcomes for mothers and neonates

BACKGROUND

Pregnant women were at increased risk for serious outcomes of 2009 pandemic influenza A virus subtype H1N1 (influenza A[H1N1]pdm09) infection, but little is known about the overall impact of the pandemic on neonatal and maternal outcomes.

METHODS

We identified live births that occurred from 1 July 2008 through 31 May 2010 in 5 Kaiser Permanente regions. Pregnant women were considered to have influenza if they had a positive result of a laboratory test for influenza virus or if they received a diagnosis of influenza during a period in which seasonal influenza virus or A(H1N1)pdm09 was the predominant circulating virus.

RESULTS

There were 111 158 births from 109 015 pregnancies involving 107 889 mothers; 368 pregnant women (0.3%) received a diagnosis of influenza due to seasonal virus, and 959 (0.9%) received a diagnosis of influenza due to A(H1N1)pdm09; 107 688 did not receive an influenza diagnosis. Pregnant women with influenza due to A(H1N1)pdm09 were more likely than women with seasonal influenza infection to be hospitalized within 30 days of the diagnosis (27% vs 12%; odds ratio [OR], 2.84 [95% confidence interval {CI}, 2.01-4.02]). Pregnant women with A(H1N1)pdm09 who started antiviral treatment ≥2 days after the diagnosis were significantly more likely to be hospitalized than those who started antiviral treatment <2 days after diagnosis (OR, 3.43 [95% CI, 1.55-7.56]). Mothers with seasonal influenza virus infection had an increased risk for having a small-for-gestational-age infant (OR, 1.59 [95% CI, 1.15-2.20]).

CONCLUSIONS

In this large, geographically diverse population, A(H1N1)pdm09 infection increased the risk for hospitalization during pregnancy. Late initiation of antiviral treatment was also associated with an increased risk for hospitalization.

2009 pandemic influenza a vaccination of pregnant women--King County, Washington State, 2009-2010

OBJECTIVES

Our objectives were to estimate 2009 pandemic influenza A (pH1N1) vaccination coverage among pregnant women and identify associated factors.

METHODS

We distributed a multimodal survey to 5341 women who gave birth between November 1, 2009, and January 31, 2010, identified by hospitals in King County, Washington State, with maternity services (n = 11).

RESULTS

Of 4205 respondents, 3233 (76.9%) reported that they had received pH1N1 vaccine during pregnancy or within 2 weeks after delivery. Women whose prenatal care provider recommended vaccine had a higher vaccination prevalence than women whose provider did not (81.5% vs 29.6%; adjusted prevalence ratio = 2.1; 95% confidence interval = 1.72, 2.58). Vaccination prevalence was lower among women who had received prenatal care from a midwife only compared with women who had received care from other providers (62.9% vs 78.8%; adjusted prevalence ratio = 0.89; 95% confidence interval = 0.83, 0.96).

CONCLUSIONS

Among pregnant women in King County, pH1N1 vaccination coverage was high. To improve coverage during nonpandemic seasons, influenza vaccine should be recommended routinely by prenatal care providers and vaccination provided where prenatal care is received. Barriers to midwives providing vaccination recommendations to patients should be explored.

2009 pandemic influenza A vaccination of pregnant women: King County, Washington State, 2009-2010

PURPOSE

The objectives were to estimate 2009 pandemic influenza A (pH1N1) vaccination coverage among pregnant women and identify associated factors.

METHODS

A multimodal survey was distributed to 5341 women who gave birth between November 1, 2009, and January 31, 2010, identified by hospitals in King County, Washington State, with maternity services (n=11).

RESULTS

Of 4205 respondents, 3233 (76.9%) reported that they had received pH1N1 vaccine during pregnancy or within 2 weeks after delivery. Women whose prenatal care provider recommended vaccine had a higher vaccination prevalence than women whose provider did not (81.5% vs 29.6%; adjusted prevalence ratio=2.1; 95% CI=1.72, 2.58). Vaccination prevalence was lower among women who had received prenatal care from a midwife only compared with women who had received care from other providers (62.9% vs 78.8%; adjusted prevalence ratio=0.89; 95% CI=0.83, 0.96).

CONCLUSIONS

Among pregnant women in King County, pH1N1 vaccination coverage was high. To improve coverage during nonpandemic seasons, influenza vaccine should be recommended routinely by prenatal care providers and vaccination provided where prenatal care is received. Barriers to midwives providing vaccination recommendations to patients should be explored.

Pandemic influenza A H1N1 2009 infection versus vaccination: a cohort study comparing immune responses in pregnancy

BACKGROUND

With the emergence of H1N1 pandemic (pH1N1) influenza, the CDC recommended that pregnant women be one of five initial target groups to receive the 2009 monovalent H1N1 vaccine, regardless of prior infection with this influenza strain. We sought to compare the immune response of pregnant women to H1N1 infection versus vaccination and to determine the extent of passive immunity conferred to the newborn.

METHODS/FINDINGS

During the 2009-2010 influenza season, we enrolled a cohort of women who either had confirmed pH1N1 infection during pregnancy, did not have pH1N1 during pregnancy but were vaccinated against pH1N1, or did not have illness or vaccination. Maternal and umbilical cord venous blood samples were collected at delivery. Hemagglutination inhibition assays (HAI) for pH1N1 were performed. Data were analyzed using linear regression analyses. HAIs were performed for matched maternal/cord blood pairs for 16 women with confirmed pH1N1 infection, 14 women vaccinated against pH1N1, and 10 women without infection or vaccination. We found that pH1N1 vaccination and wild-type infection during pregnancy did not differ with respect to (1) HAI titers at delivery, (2) HAI antibody decay slopes over time, and (3) HAI titers in the cord blood.

CONCLUSIONS

Vaccination against pH1N1 confers a similar HAI antibody response as compared to pH1N1 infection during pregnancy, both in quantity and quality. Illness or vaccination during pregnancy confers passive immunity to the newborn.

Immunogenicity of an inactivated monovalent 2009 H1N1 influenza vaccine in pregnant women

BACKGROUND

Although pregnant women are at increased risk of severe illness following influenza infection, there is relatively little information on the immunogenicity of influenza vaccines administered during pregnancy.

METHODS

We conducted a clinical trial that enrolled 120 pregnant women in which participants were randomly assigned to receive an inactivated 2009 H1N1 influenza vaccine containing either 25 μg or 49 μg of hemagglutinin (HA) in a 2-dose series with a 21-day period between administration of the first and second doses.

RESULTS

Following the first vaccination, HA inhibition (HAI) titers of ≥1:40 were detected in 93% (95% confidence interval [CI], 82%-98%) of subjects who received the 25-μg dose and 97% (95% CI, 88%-100%) of subjects receiving the 49-μg dose. In cord blood samples, HAI titers of ≥1:40 were found in 87% (95% CI, 73%-96%) of samples from the 25-μg dose group and in 89% (95% CI, 76%-96%) from the 49-μg dose group. Microneutralization titers tended to be higher than HAI titers, but the patterns of response were similar.

CONCLUSIONS

In pregnant women, 1 dose of an inactivated 2009 H1N1 influenza vaccine containing 25 μg of HA elicited an antibody response typically associated with protection against influenza infection. Efficient transplacental transfer of antibody was also documented.

Pandemic (H1N1) 2009 virus infection during pregnancy in South India

OBJECTIVE

To assess the clinical profile of pregnant/puerperal women from a semi-urban Indian population who were infected with pandemic (H1N1) 2009 virus (P[H1N1]2009v) and to evaluate their outcome.

METHODS

In a cross-sectional study, 566 women (79 pregnant/puerperal, 487 nonpregnant) who presented to a tertiary care hospital with influenza-like illness were tested for P(H1N1)2009v by real-time reverse transcriptase polymerase chain reaction. Outcomes measures were the maternal mortality and the perinatal mortality rate (PMR).

RESULTS

Twenty (25%) pregnant/puerperal and 144 (30%) nonpregnant women tested positive for P(H1N1)2009v, with 5 pregnant and 3 postpartum women requiring admission to the intensive care unit (ICU). P(H1N1)2009v-related mortality was higher in pregnant than nonpregnant women (25% versus 8%; P=0.04). In the pregnant/puerperal cohort, factors associated with death included delayed presentation (median 6days versus 1.5days in survivors; P=0.007), need for ICU admission (P=0.004), need for ventilation (P=0.001), and renal failure (P=0.001). The PMR was 55.5/1000 births compared with 33.5/1000 births in the hospital overall during the study period.

CONCLUSION

In a low-income country, P(H1N1)2009v infection in pregnancy is associated with considerable mortality. Delayed presentation to a tertiary care center, lack of awareness, and restricted access to treatment might have contributed to the high mortality.

Seasonal and 2009 pandemic influenza A (H1N1) virus infection during pregnancy: a population-based study of hospitalized cases

We sought to describe characteristics of hospitalized reproductive-aged (15-44 years) women with seasonal (2005/2006 through 2008/2009) and 2009 pandemic influenza A (H1N1) virus infection. We used population-based data from the Emerging Infections Program in 10 US states, and compared characteristics of pregnant (n = 150) and nonpregnant (n = 489) seasonal, and pregnant (n = 489) and nonpregnant (n = 1088) pandemic influenza cases using χ(2) and Fisher's exact tests. Pregnant women represented 23.5% and 31.0% of all reproductive-aged women hospitalized for seasonal and pandemic influenza, respectively. Significantly more nonpregnant than pregnant women with seasonal (71.2% vs 36.0%) and pandemic (69.7% vs 31.9%) influenza had an underlying medical condition other than pregnancy. Antiviral treatment was significantly more common with pandemic than seasonal influenza for both pregnant (86.5% vs 24.0%) and nonpregnant (82.0% vs 55.2%) women. Pregnant women comprised a significant proportion of influenza-hospitalized reproductive-aged women, underscoring the importance of influenza vaccination during pregnancy.

Behaviors and perceptions regarding seasonal and H1N1 influenza vaccination during pregnancy

We examined vaccination rates during pregnancy against both seasonal and pandemic H1N1 influenza and reasons for nonadherence to recommended guidelines during the 2009 through 2010 influenza season. Demographic and vaccination data were collected using a cross-sectional approach. Among 813 postpartum women, 520 (64%) reported receiving the seasonal influenza vaccination and 439 (54%) reported receiving the H1N1 influenza vaccination during pregnancy. Most received vaccinations at their obstetrician's office. Major reasons for not receiving vaccination were: not knowledgeable about the vaccine importance (25%), concerns for effects on fetal and maternal health (18% and 9%, respectively), and not knowledgeable about where to obtain vaccination (9%). Reported H1N1 influenza vaccination rates were significantly lower in blacks (37%) compared with non-Hispanic whites, Hispanics, and Asian/other (57%, 59%, and 58%, respectively; P < .0001). Subsequent campaigns for improving vaccination rates in pregnancy should focus on educating patients about vaccine importance and safety.

Influence of timing of seasonal influenza vaccination on effectiveness and cost-effectiveness in pregnancy

The purpose of this review was to estimate the impact of timing of seasonal influenza vaccination during pregnancy on health and economic outcomes. Cost-effectiveness analysis with a dynamic model of the US population of pregnant women and infants who were <6 months incorporated seasonal variation in influenza incidence. Compared with no vaccination, seasonal influenza vaccination in pregnancy costs $70,089 per quality-adjusted life year. Most of the benefit for infants was limited to those whose mothers were vaccinated within the first 4 weeks of vaccine availability. Once all women who were pregnant at the time of vaccine availability were vaccinated, vaccination of newly pregnant women had benefits for mothers but not infants. Delay of vaccination beyond November reduced both effectiveness and cost-effectiveness. The greatest population benefit from seasonal influenza vaccination in pregnancy was realized if pregnant women were vaccinated as soon as possible after trivalent inactivated influenza vaccine became available. Efforts to increase vaccine rates should be concentrated early in the influenza season.