Dataset Information

Impact of Timing of Influenza Vaccination in Pregnancy on Transplacental Antibody Transfer, Influenza Incidence, and Birth Outcomes: A Randomized Trial in Rural Nepal.

ABSTRACT: Background:Maternal influenza vaccination protects mothers and their infants in low resource settings, but little is known about whether the protection varies by gestational age at vaccination. Methods:Women of childbearing age in rural southern Nepal were surveilled for pregnancy, consented and randomized to receive maternal influenza vaccination or placebo, with randomization stratified on gestational age (17-25 or 26-34 weeks). Enrollment occurred in 2 annual cohorts, and vaccinations occurred from April 2011 through September 2013. Results:In sum, 3693 women consented and enrolled, resulting in 3646 live births. Although cord blood antibody titers and the rise in maternal titers were generally greater when women were vaccinated later in pregnancy, this was not statistically significant. The incidence risk ratio (IRR) for maternal influenza in pregnancy through 6 months postpartum was 0.62 (95% confidence interval [CI]: 0.35, 1.10) for those vaccinated 17-25 weeks gestation and 0.89 (95% CI: 0.39, 2.00) for those 26-34 weeks. Infant influenza IRRs were 0.73 (95% CI: 0.51, 1.05) for those whose mothers were vaccinated earlier in gestation, and 0.63 (95% CI: 0.37, 1.08) for those later. Relative risks (RR) for low birthweight were 0.83 (95% CI: 0.71, 0.98) and 0.90 (95% CI: 0.72, 1.12) for 17-25 and 26-34 weeks gestation at vaccination, respectively. IRRs did not differ for small-for-gestational age or preterm. No RRs were statistically different by timing of vaccine receipt. Conclusions:Vaccine efficacy did not vary by gestational age at vaccination, making maternal influenza immunization programs easier to implement where women present for care late in pregnancy. Clinical Trials Registration:NCT01034254.

SUBMITTER: Katz J

PROVIDER: S-EPMC6051462 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Impact of Timing of Influenza Vaccination in Pregnancy on Transplacental Antibody Transfer, Influenza Incidence, and Birth Outcomes: A Randomized Trial in Rural Nepal.

Katz Joanne J Englund Janet A JA Steinhoff Mark C MC Khatry Subarna K SK Shrestha Laxman L Kuypers Jane J Mullany Luke C LC Chu Helen Y HY LeClerq Steven C SC Kozuki Naoko N Tielsch James M JM

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 20180701 3

<h4>Background</h4>Maternal influenza vaccination protects mothers and their infants in low resource settings, but little is known about whether the protection varies by gestational age at vaccination.<h4>Methods</h4>Women of childbearing age in rural southern Nepal were surveilled for pregnancy, consented and randomized to receive maternal influenza vaccination or placebo, with randomization stratified on gestational age (17-25 or 26-34 weeks). Enrollment occurred in 2 annual cohorts, and vacci ...[more]

PMID: 29452372

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Project description:Quantitative validation studies alone may not be able to distinguish between instances when participants did not accurately report an event vs when participants did not understand a question. We used an explanatory qualitative study design to acquire an in-depth understanding of why some mothers in rural Nepal overestimate birth size of their newborn and their length of pregnancy.We conducted two focus group discussions (FGDs) with study staff who administered a quantitative questionnaire and 12 in-depth interviews (IDIs) with mothers who had participated in a quantitative validation study. Transcripts were coded and analyzed for themes in patterns of meaning within and across FGDs and IDIs. Using this thematic map, we synthesized our data into common and divergent responses from participants to facilitate our interpretation of the quantitative findings.We identified five themes specific to this analysis: difficulties with the length of pregnancy question, challenges in administering the birth size question, the perceived effect of time since birth on mothers' ability to remember information, the language and style differences specific to this setting, and the study context shaping the relationship between study staff and mothers who participated and how this may have influenced mothers' responses. Visual aids may help to scale the question about birth size within a cultural frame of reference for maternal reports to be more interpretable. Among both study staff and mothers, a longer period of time since the birth of a child was thought to be associated with diminished accuracy of maternal reports, a perception not supported by our previously published quantitative findings.Poor validity of low birth weight (LBW) and preterm birth indicators based on maternal reports may be partly attributed to challenges in maternal understanding of questions assessing birth size and length of pregnancy. Additional research is needed to confirm these findings regarding maternal comprehension and to further evaluate the utility of visual aids developed for this study.

Project description:Studies have shown that influenza vaccination during pregnancy reduces the risk of influenza disease in pregnant women and their offspring. Some have proposed that maternal vaccination may also have beneficial effects on birth outcomes. In 2014, we conducted an observational study to test this hypothesis using data from two large hospitals in Managua, Nicaragua.We conducted a retrospective cohort study to evaluate associations between influenza vaccination and birth outcomes. We carried out interviews and reviewed medical records post-partum to collect data on demographics, influenza vaccination during pregnancy, birth outcomes and other risk factors associated with adverse neonatal outcomes. We used influenza surveillance data to adjust for timing of influenza circulation. We assessed self-reports of influenza vaccination status by further reviewing medical records of those who self-reported but did not have readily available evidence of vaccination status. We performed multiple logistic regression (MLR) and propensity score matching (PSM).A total of 3268 women were included in the final analysis. Of these, 55% had received influenza vaccination in 2014. Overall, we did not observe statistically significant associations between influenza vaccination and birth outcomes after adjusting for risk factors, with either MLR or PSM. With PSM, after adjusting for risk factors, we observed protective associations between influenza vaccination in the second and third trimester and preterm birth (aOR: 0.87; 95% confidence interval (CI): 0.75-0.99 and aOR: 0.66; 95% CI: 0.45-0.96, respectively) and between influenza vaccination in the second trimester and low birth weight (aOR: 0.80; 95% CI: 0.64-0.97).We found evidence to support an association between influenza vaccination and birth outcomes by trimester of receipt with data from an urban population in Nicaragua. The study had significant selection and recall biases. Prospective studies are needed to minimize these biases.

Project description:BackgroundNausea and vomiting are experienced by a majority of pregnant women worldwide. Previous studies have yielded conflicting results regarding their impact on birth outcomes and few studies have examined this relationship in settings with limited resources. We aimed to determine the effect of nausea, vomiting and poor appetite during pregnancy on birth outcomes in rural Nepal.MethodsObservational cohort study using data collected in two randomized, community-based trials to assess the effect of influenza immunization during pregnancy on reproductive and respiratory outcomes among pregnant women and their offspring. Pregnant women in Sarlahi District, Nepal were recruited from 2011 to 2013. Exposure was defined as nausea, vomiting or poor appetite at any point during pregnancy and by trimester; symptoms were recorded monthly throughout pregnancy. Adverse outcomes were low birth weight (LBW), preterm birth and small for gestational age (SGA). Adjusted relative risks (aRR) with 95% CIs are reported from Poisson regressions with robust variance.ResultsAmong 3,623 pregnant women, the cumulative incidence of nausea, vomiting or poor appetite was 49.5% (n = 1793) throughout pregnancy and 60.6% (n = 731) in the first trimester. Significantly higher aRRs of LBW and SGA were observed among women experiencing symptoms during pregnancy as compared to symptom free women (LBW: aRR 1.20; 95% CI 1.05 1.28; SGA: aRR 1.16; 95% CI 1.05 1.28). Symptoms in the first trimester were not significantly associated with any of the outcomes. In the second trimester, we observed significantly higher aRRs for LBW and SGA (LBW: aRR 1.17; 95% CI 1.01 1.36; SGA: aRR 1.16; 95% CI 1.05 1.29) and a significantly lower aRR for preterm birth (aRR 0.75; 95% CI 0.59 0.96). In the third trimester, we observed significantly higher aRRs for LBW and SGA (LBW: aRR 1.20; 95% CI 1.01 1.43; SGA: aRR 1.14; 95% CI 1.01 1.29).ConclusionsSymptoms of nausea, vomiting or poor appetite during pregnancy are associated with LBW, SGA and preterm birth in a setting with limited resources, especially beyond the first trimester.Trial registrationProspectively registered at ClinicalTrials.gov on Dec 17, 2009 ( NCT01034254 ).

Dataset Information

Impact of Timing of Influenza Vaccination in Pregnancy on Transplacental Antibody Transfer, Influenza Incidence, and Birth Outcomes: A Randomized Trial in Rural Nepal.

Publications

Impact of Timing of Influenza Vaccination in Pregnancy on Transplacental Antibody Transfer, Influenza Incidence, and Birth Outcomes: A Randomized Trial in Rural Nepal.

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