Effects of influenza on pregnant women and infants

Immunogenicity of inactivated quadrivalent influenza vaccine in pregnant women, including the level of postvaccination antibodies in umbilical cord blood

BACKGROUND

Infants and pregnant women are particularly vulnerable to severe illness and complications of influenza. It is necessary to increase knowledge about the safety and effectiveness of influenza vaccination during pregnancy to improve awareness among patients and healthcare professionals and increase to increase vaccination coverage.

METHODS

A prospective, single-group clinical study was performed in the 2021/2022 and 2022/2023 seasons. The aim of the study was to assess the immunogenicity and tolerance of quadrivalent influenza vaccine (IIV4) in pregnant women, to evaluate transplacental antibody (AB) transfer after IIV4 administration, and to estimate optimal gestational age for vaccination. A group of 62 pregnant women between 14 and 37 weeks of gestation, including 59 mother-child pairs, underwent vaccination with IIV4. The humoral immune response was assessed using the EMA criteria.

RESULTS

Baseline seroprotection for all IIV4 strains was significantly correlated with previous vaccinations (p < .5). The postvaccination seroprotection ranged between 71 % and 94 %. A significant increase in AB titers was observed for all vaccine strains (p < .0000). No significant differences were observed in seroprotection and seroconversion rates or transplacental AB transfer between women vaccinated in the 2nd vs 3rd trimester of pregnancy. All IIV4 strains used in the study met at least 1 of the 3 EMA/CPMP immunogenicity criteria and may thus be considered immunogenic. Seroprotection for A/H1N1/pdm09, A/H3N2, B/lineage Victoria (B/V), and B/lineage Yamagata (B/Y) antigens was achieved by 97 %, 95 %, 59 %, and 85 % of neonates, respectively. Over 43 % of participants reported solicited injection site reactions. None of the participants reported severe or unsolicited adverse events.

CONCLUSIONS

IIV4 induced a strong immune response in pregnant women and a high rate of seroprotection in neonates. Immune protection in children did not differ according to the trimester of vaccination in pregnancy. IIV4 was well tolerated by pregnant women.

Long COVID after SARS-CoV-2 during pregnancy in the United States

Pregnancy alters immune responses and clinical manifestations of COVID-19, but its impact on Long COVID remains uncertain. This study investigated Long COVID risk in individuals with SARS-CoV-2 infection during pregnancy compared to reproductive-age females infected outside of pregnancy. A retrospective analysis of two U.S. databases, the National Patient-Centered Clinical Research Network (PCORnet) and the National COVID Cohort Collaborative (N3C), identified 29,975 pregnant individuals (aged 18-50) with SARS-CoV-2 infection in pregnancy from PCORnet and 42,176 from N3C between March 2020 and June 2023. At 180 days after infection, estimated Long COVID risks for those infected during pregnancy were 16.47 per 100 persons (95% CI, 16.00-16.95) in PCORnet using the PCORnet computational phenotype (CP) model and 4.37 per 100 persons (95% CI, 4.18-4.57) in N3C using the N3C CP model. Compared to matched non-pregnant individuals, the adjusted hazard ratios for Long COVID were 0.86 (95% CI, 0.83-0.90) in PCORnet and 0.70 (95% CI, 0.66-0.74) in N3C. The observed risk factors for Long COVID included Black race/ethnicity, advanced maternal age, first- and second-trimester infection, obesity, and comorbid conditions. While the findings suggest a high incidence of Long COVID among pregnant individuals, their risk was lower than that of matched non-pregnant females.

Transplacental Antibodies: Role of Maternal Vaccines and Immunity

Transplacental transfer of maternal antibody in utero is a key component of neonatal immunity. This transfer of maternal antibody across the placenta provides temporary protection from bacterial and viral pathogens that threaten newborn health. Maternal vaccination before and during pregnancy may be used to boost maternal immunity and optimize neonatal protection from infection and serious illness.

Do Pregnant Persons Want Influenza Vaccines? Knowledge, Attitudes, Perceptions, and Practices Toward Influenza Vaccines in 8 Low- and Middle-Income Countries

BACKGROUND

Vaccination is the most effective way to prevent influenza infection and adverse outcomes; despite global recommendations to vaccinate pregnant persons, access to influenza vaccines remains low. We explored knowledge, attitudes, and practices of pregnant persons to inform actions to improve vaccine uptake.

METHODS

We pooled data from cross-sectional surveys assessing pregnant persons' attitudes toward influenza vaccines in 8 low- and middle-income countries. Countries used standard methods to measure attitudes and intents toward influenza vaccination. We stratified by presence/absence of a national influenza vaccination program, income group, geographic region, and individual-level factors.

RESULTS

Our analysis included 8556 pregnant persons from 8 countries. Most pregnant persons (6323, 74%) were willing to receive influenza vaccine if it was offered for free. Willingness differed by presence of an existing influenza vaccination program; acceptance was higher in countries without programs (2383, 89%) than in those with programs (3940, 67%, P < .001).

CONCLUSIONS

Most pregnant persons in middle-income countries, regardless of influenza vaccination program status, were willing to be vaccinated against influenza if the vaccine was provided free of charge. National investments in influenza vaccination programs present an opportunity to avert illness both in pregnant persons themselves and in their newborn babies.

Knowledge, attitudes, and perceptions of influenza vaccine among pregnant women in Minhang District, Shanghai

This study aimed to assess the attitudes and willingness of pregnant women to receive the influenza vaccine and the factors influencing their decisions. A sample survey was conducted among pregnant women receiving prenatal care at various medical institutions in Minhang District, Shanghai, from March to June 2023. The survey included inquiries about demographic information, knowledge, and perception of influenza disease and influenza vaccine. Logistic regression models and chi-square tests were used to analyze the data. 6.9% (78/1125) of participants considered receiving the influenza vaccine during pregnancy. Participants with graduate education or above (OR = 4.632, 95%CI: 1.046-20.517), non-office workers (OR = 2.784, 95%CI: 1.560-4.970), and participants whose spouses were not office workers (OR = 0.518, 95% CI: 0.294-0.913) were significantly associated with high intent to vaccinate. Participants with superior knowledge (>30 points) exhibited greater willingness (p < .001). Participants who viewed post-influenza symptoms as mild had a significantly lower willingness to vaccinate during pregnancy (2.3%), compared to those who disagreed (p = .015). Conversely, those recognizing a heightened risk of hospitalization due to respiratory diseases in pregnant women post-influenza were significantly more inclined to vaccinate during pregnancy (8.8%) (p = .007). Participants recognizing benefits uniformly expressed willingness to receive the influenza vaccine during pregnancy (p < .001), while those perceiving barriers uniformly rejected vaccination (p < .001). Higher education, non-office worker status, and having an office worker spouse correlate with greater willingness to receive the influenza vaccine during pregnancy. Enhanced knowledge and accurate perceptions of influenza and its vaccine influenced willingness. Accumulating knowledge about influenza and its vaccine fosters accurate perceptions. Notably, overall willingness to vaccinate during pregnancy remains low, likely due to safety concerns, and lack of accurate perceptions. Targeted health education, improved communication between healthcare providers and pregnant women, and campaigns highlighting vaccine benefits for mothers and children are essential.

Safety of quadrivalent recombinant influenza vaccine in pregnant persons and their infants

Background

The Advisory Committee on Immunization Practices (ACIP) and the American College of Obstetricians and Gynecologists (ACOG) recommend that all pregnant persons receive any licensed, recommended, and age-appropriate inactivated influenza vaccine (SD-IIV) or recombinant influenza vaccine (RIV) to protect against influenza and influenza-related complications. RIV was safe and efficacious in pre- and postlicensure studies, however there is limited RIV safety data in pregnant persons.

Objective

To evaluate the safety of quadrivalent recombinant influenza vaccine (RIV4) versus a quadrivalent standard-dose, inactivated influenza (SD-IIV4) in a large cohort of pregnant persons and their infants.

Study Design

This postlicensure observational safety study conducted at Kaiser Permanente Northern California evaluated the subset of pregnant persons vaccinated in routine care as part of a larger cluster-randomized vaccine effectiveness study comparing RIV4 vs. SD-IIV4 (ClinicalTrials.gov NCT03694392). We identified pregnancy (spontaneous abortion, preterm labor, stillbirth/fetal death, congenital/fetal anomalies detected during pregnancy, eclampsia/pre-eclampsia, placental abruption), birth (preterm birth, low birth weight, small for gestational age), and neonatal/infant outcomes (infant death, failure to thrive, congenital anomalies detected after delivery) using diagnostic codes among pregnant persons ≥18 years immunized with RIV4 or SD-IIV4 during the 2018/19 and 2019/20 influenza seasons and their infants. We used conditional logistic regression adjusted for age group, race, ethnicity, trimester of influenza vaccination, comorbidities, and BMI, stratified by gestational age to estimate the odds ratio (OR) of pregnancy outcomes following vaccination with RIV4 vs. SD-IIV4. Using logistic regression, we separately estimated the adjusted OR of birth and neonatal/infant outcomes in the first year of life (eg, death) in infants of RIV4 vs. SD-IIV4 vaccinated pregnant persons.

Results

The study population included 48,781 pregnant persons (RIV4 = 14,981; SD-IIV4 = 33,800) and 47,394 live births (RIV4 = 14,538; SD-IIV4 = 32,856). There was no statistical difference in any pregnancy outcome or in birth and neonatal/infant outcome between RIV4 vs. SD-IIV4 vaccinated pregnant persons and their infants.

Conclusion

Compared with receipt of a SD-IIV4 during pregnancy, this large study did not identify any pregnancy, birth, or neonatal/infant safety concerns following receipt of a RIV4 during pregnancy and demonstrates that the safety of RIV4 in pregnancy was similar to SD-IIV4. This study provides additional evidence regarding the safety of influenza vaccination in pregnant persons and further supports ACIP and ACOG recommendations that all pregnant persons receive an inactivated or recombinant influenza vaccine.

An analysis of virtual triage utilization by pregnant women prior to and during the COVID-19 pandemic

Objective

This analysis describes the use patterns of web-based virtual triage (VT) by pregnant patients before and during the first two years of the COVID-19 pandemic, and how the pandemic influenced frequency of VT use, nature of symptoms reported, and the associated implications for maternal healthcare delivery.

Methods

An online survey of 36,910 patients who reported pregnancy was completed between January 1, 2019 and June 30, 2022. The data were segmented into six month periods to allow comparative analyses of usage frequency and changes in initial complaints over the study period, with particular emphasis on the early months of the COVID-19 pandemic. Descriptive statistics and trend analyses were used to identify significant shifts in symptom reporting and user demographics.

Results

A marked increase in the utilization of VT by pregnant women during the pandemic occurred. The percentage of pregnant users grew from 0.32% in the first half of 2019 to 0.85% in late 2021, with the greatest rise (213%) in the first six months of 2020. The most common symptoms reported were abdominal pain, headache, nausea, back pain, fatigue and cough. Pre-pandemic, VT use focused on prospective mothers learning about the potential causes of typical symptoms occurring during pregnancy, but during the pandemic there was a substantial increase in reporting symptoms associated with acute respiratory infections such as cough, nasal congestion, and dyspnea.

Conclusions

The COVID-19 pandemic significantly influenced the use of VT by pregnant women, with a shift towards addressing concerns related to respiratory symptoms and potential COVID-19 exposure. These findings underline the significant role of digital health tools in maintaining access to health information during times of crisis and highlight the evolving needs of pregnant patients in such settings.

Birth Outcomes After Pertussis and Influenza Diagnosed in Pregnancy: A Retrospective, Population-Based Study

OBJECTIVE

Adverse birth outcomes and the maternal severity of influenza in pregnancy are well documented but information on pertussis is limited.

DESIGN

Population-based linkage data were collected during 2001-2016.

SETTING

New South Wales, Australia.

POPULATION OR SAMPLE

A total of 1 453 037 singleton births.

METHODS

Cox regression was used to estimate the associations between pertussis or influenza during pregnancy and birth outcomes with adjustment of covariates.

MAIN OUTCOME MEASURES

Adverse birth outcomes (preterm birth and low birth weight).

RESULTS

Among 1 453 037 singleton births over 16 years, we identified pertussis in 925 (49; 5.3% hospitalised) and influenza in 2850 (1092; 38.3% hospitalised) women during pregnancy. Cases of pertussis were similarly distributed by trimester (32% 3rd) whereas 46% of influenza cases were in the 3rd trimester. Younger age, previous birth, and being overseas-born were associated with both pertussis and influenza, whereas identifying as Aboriginal or Torres Strait Islander, hypertension or diabetes before and during pregnancy, and a number of other factors were only associated with influenza. Both pertussis and influenza in pregnancy were associated with increased risk of preterm birth (pertussis: aHR = 1.30, 95% CI 1.01-1.68; influenza: aHR = 1.56, 95% CI 1.36-1.79) and these increased risks were greater when infections in the period within 2 weeks of birth were considered (pertussis: aHR = 2.36, 95% CI 1.26-4.41; influenza: aHR = 2.29, 95% CI 1.78-2.96).

CONCLUSIONS

Maternal pertussis and influenza infections close to the time of birth were associated with adverse birth outcomes. These findings highlight the benefits of vaccination during pregnancy.

A novel scale for assessing the risk of low birthweight: Birthweight questionnaire

BACKGROUND

The birthweight of a newborn is critical to their health, development, and well-being. Previous studies that used maternal characteristics to predict birthweight did not employ a harmonised scale to assess the risk of low birthweight (LBW).

OBJECTIVE

The goal of this study was to develop a new instrument that uses items on a uniform scale to assess the risk of an LBW in a pregnant woman.

METHODS

Item response theory was employed to evaluate a similar existing scale, and some weaknesses were identified.

RESULTS

Based on the observed weaknesses of the existing scale, a new uniform scale was developed, which is a 3-point Likert scale consisting of seven items.

CONCLUSION

The scale, termed birthweight questionnaire, is a valuable tool for collecting data that could assist in assessing the risk of an LBW at every stage of pregnancy.

Gestational influenza A virus infection elicits nonresolving vascular dysfunction and T-cell accumulation in the aorta of mice

T-cell accumulation within the aorta promotes endothelial dysfunction and the genesis of cardiovascular disease, including hypertension and atherosclerosis. Viral infection during pregnancy is also known to mediate marked acute endothelial dysfunction, but it is not clear whether T cells are recruited to the aorta and whether the dysfunction persists postpartum. Here, we demonstrate that influenza A virus (IAV) infection during pregnancy in a murine model resulted in endothelial dysfunction of the aorta, which persisted for up to 60 days postinfection and was associated with higher levels of IFN-γ mRNA expression within the tissue. In the absence of infection, low numbers of naïve CD4+ and CD8+ T cells, central memory T cells, and effector memory T cells were observed in the aorta. However, with IAV infection, these T-cell subsets were significantly increased with a notable accumulation of IAV-specific CD8+ effector memory T cells. Critically, this increase was maintained out to at least 60 days. In contrast, IAV infection in nonpregnant female mice resulted in modest endothelial dysfunction with no accumulation of T cells within the aorta. These data, therefore, demonstrate that the aorta is a site of T-cell recruitment and retention after IAV infection during pregnancy. Although IAV-specific memory T cells could theoretically confer protection against future influenza infection, nonspecific memory T-cell activation and IFN-γ production in the aorta could also contribute to future endothelial dysfunction and cardiovascular disease.NEW & NOTEWORTHY Pregnancy is a risk factor for cardiovascular complications to influenza A virus (IAV) infection. We demonstrate that gestational IAV infection caused endothelial dysfunction of the maternal aorta, which persisted for 60 days postinfection in mice. Various T cells accumulated within the aorta at 60 days because of the infection, and this was associated with elevated levels of the proinflammatory cytokine, IFN-γ. Our study demonstrates a novel "long influenza" cardiovascular phenotype in female mice.

Postpartum Interventions to Increase Maternal Vaccination Uptake: Is It Worth It?

BACKGROUND/OBJECTIVES

Vaccination of pregnant and postpartum women for pertussis, influenza and COVID-19 not only protects themselves but also offspring. Despite the benefits of this approach, vaccination uptake remains suboptimal in pregnancy. Where the opportunity to be vaccinated in pregnancy is missed, the offer of vaccination in the post-partum period may be an alternative strategy. The aim of this systematic review is to assess the impact of interventions to increase vaccination uptake in the postpartum period on vaccination uptake.

METHODS

A literature search was performed in MEDLINE, including interventional studies promoting vaccination uptake in postpartum women published between 2009 and 2024. The search was conducted according to PRISMA guidelines and registered with PROSPERO.

RESULTS

We finally included 16 studies in the review, and the primary outcome was vaccination uptake in the postpartum period. The most significant factors for increasing uptake were recommendation from healthcare providers, type of interventions used, and delivery of vaccines in the maternity wards or the community.

CONCLUSIONS

In conclusion, maternal vaccination rates in the postpartum period may increase with targeted education by healthcare professionals and positive reinforcement. The interventions described in these studies could be applied in the healthcare systems worldwide.

Influenza in Pregnancy: Maternal, Obstetric, and Fetal Implications, Diagnosis, and Management

Influenza(flu) in pregnancy is associated with higher rates of hospitalization, ICU admission, and death and with increased odds of congenital anomalies and stillbirth, but not preterm birth. Clinical manifestations of flu in pregnancy are the same as nonpregnant patients. Pregnant individuals with flu-like symptoms or flu exposure should be treated with antivirals. Diagnostic testing is not needed. Oseltamivir is the mainstay of treatment(and prophylaxis), and when given within 48 hours of symptom onset, it decreases morbidity and mortality. Influenza is associated with worse maternal, obstetric, and neonatal outcomes. These risks are mitigated by early oseltamivir treatment and maternal vaccination; hence the recommendation for universal vaccination in pregnancy.

From Womb to World: Exploring the Immunological Connections between Mother and Child

Mother and child are immunologically interconnected by mechanisms that we are only beginning to understand. During pregnancy, multiple molecular and cellular factors of maternal origin are transferred across the placenta and influence the development and function of the fetal and newborn immune system. Altered maternal immune states arising from pregnancy-associated infections or immunizations have the potential to program offspring immune function in ways that may have long-term health consequences. In this study, we review current literature on the impact of prenatal infection and vaccination on the developing immune system, highlight knowledge gaps, and look to the horizon to envision maternal interventions that could benefit both the mother and her child.

Ventricular-subventricular zone stem cell niche adaptations in a mouse model of post-infectious hydrocephalus

Congenital post-infectious hydrocephalus (PIH) is a condition characterized by enlargement of the ventricular system, consequently imposing a burden on the associated stem cell niche, the ventricular-subventricular zone (V-SVZ). To investigate how the V-SVZ adapts in PIH, we developed a mouse model of influenza virus-induced PIH based on direct intracerebroventricular injection of mouse-adapted influenza virus at two distinct time points: embryonic day 16 (E16), when stem cells line the ventricle, and postnatal day 4 (P4), when an ependymal monolayer covers the ventricle surface and stem cells retain only a thin ventricle-contacting process. Global hydrocephalus with associated regions of astrogliosis along the lateral ventricle was found in 82% of the mice infected at P4. Increased ependymogenesis was observed at gliotic borders and throughout areas exhibiting intact ependyma based on tracking of newly divided cells. Additionally, in areas of intact ependyma, stem cell numbers were reduced; however, we found no significant reduction in new neurons reaching the olfactory bulb following onset of ventriculomegaly. At P4, injection of only the non-infectious viral component neuraminidase resulted in limited, region-specific ventriculomegaly due to absence of cell-to-cell transmission. In contrast, at E16 intracerebroventricular injection of influenza virus resulted in death at birth due to hypoxia and multiorgan hemorrhage, suggesting an age-dependent advantage in neonates, while the viral component neuraminidase resulted in minimal, or no, ventriculomegaly. In summary, we tracked acute adaptations of the V-SVZ stem cell niche following onset of ventriculomegaly and describe developmental changes that help mitigate the severity of congenital PIH.

Viral infections in pregnancy and impact on offspring neurodevelopment: mechanisms and lessons learned

Pregnant individuals with viral illness may experience significant morbidity and have higher rates of pregnancy and neonatal complications. With the growing number of viral infections and new viral pandemics, it is important to examine the effects of infection during pregnancy on both the gestational parent and the offspring. Febrile illness and inflammation during pregnancy are correlated with risk for autism, attention deficit/hyperactivity disorder, and developmental delay in the offspring in human and animal models. Historical viral epidemics had limited follow-up of the offspring of affected pregnancies. Infants exposed to seasonal influenza and the 2009 H1N1 influenza virus experienced increased risks of congenital malformations and neuropsychiatric conditions. Zika virus exposure in utero can lead to a spectrum of abnormalities, ranging from severe microcephaly to neurodevelopmental delays which may appear later in childhood and in the absence of Zika-related birth defects. Vertical infection with severe acute respiratory syndrome coronavirus-2 has occurred rarely, but there appears to be a risk for developmental delays in the infants with antenatal exposure. Determining how illness from infection during pregnancy and specific viral pathogens can affect pregnancy and neurodevelopmental outcomes of offspring can better prepare the community to care for these children as they grow. IMPACT: Viral infections have impacted pregnant people and their offspring throughout history. Antenatal exposure to maternal fever and inflammation may increase risk of developmental and neurobehavioral disorders in infants and children. The recent SARS-CoV-2 pandemic stresses the importance of longitudinal studies to follow pregnancies and offspring neurodevelopment.

Association Between Influenza Vaccination and SARS-CoV-2 Infection

BACKGROUND

Recent data in nonpregnant individuals suggest a protective effect of influenza vaccination against SARS-CoV-2 infection and its severity.

OBJECTIVES

Our primary objective was to evaluate whether influenza vaccination was associated with COVID-19 severity and pregnancy and neonatal outcomes among those infected with SARS-CoV-2. The secondary objective was to examine the association between influenza vaccination and SARS-CoV-2 infection.

STUDY DESIGN

Secondary analysis of a multicenter retrospective cohort of pregnant people who tested positive for SARS-CoV-2 between March and August 2020, and a cohort of random deliveries during the same time period. The associations between 2019 influenza vaccination and the primary outcome of moderate-to-critical COVID-19 as well as maternal and perinatal outcomes were examined among all people who tested positive for SARS-CoV-2 between March and August 2020. The association between 2019 influenza vaccination and having a positive SARS-CoV-2 test was examined among a cohort of individuals who delivered on randomly selected dates between March and August 2020. Univariable and multivariable analyses were performed.

RESULTS

Of 2325 people who tested positive for SARS-CoV-2, 1068 (45.9%) were vaccinated against influenza in 2019. Those who received the influenza vaccine were older, leaner, more likely to have private insurance, and identify as White or Hispanic. They were less likely to smoke tobacco and identify as Black. Overall, 419 (18.0%) had moderate, 193 (8.3%) severe, and 52 (2.2%) critical COVID-19. There was no association between influenza vaccination and moderate-to-critical COVID-19 (29.2% vs. 28.0%, adjusted OR 1.10, 95% CI 0.90-1.34) or adverse maternal and perinatal outcomes among those who tested positive. Of 8152 people who delivered in 2020, 4658 (57.1%) received the influenza vaccine. Prior vaccination was not associated with a difference in the odds of SARS-CoV-2 infection (3.8% vs. 4.2%, adjusted OR 0.94, 95% CI 0.74-1.19).

CONCLUSION

Prior influenza vaccination was not associated with decreased severity of COVID-19 or lower odds of SARS-CoV-2 infection in pregnancy.

Vaccination: Adherence and Hesitancy among Pregnant Women for COVID-19, Pertussis, and Influenza Vaccines

In the realm of antenatal care, vaccinations serve as a cornerstone, crucial for safeguarding the health of both the mother and the fetus, while also extending protection to the newborn against communicable diseases. Nevertheless, vaccine adherence among pregnant women remains very low. The aim of our study was to evaluate the uptake of vaccines (influence, pertussis, and COVID-19) among women during pregnancy and to understand pregnant women's knowledge of vaccines and the diseases they protect against. The purpose was to investigate the reasons why pregnant women chose not to be vaccinated and to develop effective strategies for informing them about the importance of vaccination for both maternal and fetal safety. A prospective observational study was conducted in the Department of Obstetrics and Gynaecology, "Ospedale Santa Maria della Misericordia" in Udine, from 1 December 2021 to 30 June 2022. During this period, a self-completed paper questionnaire was administered to women at the end of pregnancy or during the puerperium. A total of 161 questionnaires were collected. Higher educational level was found to be significantly associated with influenza vaccination uptake (p = 0.037, OR = 2.18, 95% CI 1.05-4.51). Similarly, for pertussis vaccination, adherence was mainly associated with higher educational level (p = 0.014, OR = 2.83, 95% CI 1.24-6.47), but also with Italian nationality (p = 0.003, OR = 3.36, 95% CI 1.56-8.43) and pregnancy attended by a midwife or private gynecologist (p = 0.028, OR = 0.39, 95% CI 0.17-0.90). Regarding the COVID-19 vaccine, the only factor positively influencing uptake was Italian nationality (p = 0.044, OR = 2.66, 95% CI 1.03-6.91). Women's fear that vaccines would endanger the fetus appeared to be the most important reason for refusing vaccinations. Simultaneously, patients also exhibited a desire to receive more information about maternal vaccination, particularly from their general physician or gynecologist. For this reason, it is imperative to enhance maternal vaccination counselling, making it a routine step in prenatal care from the first antenatal visit until the postpartum period.

Interventional study to improve pertussis and influenza vaccination uptake in pregnant women

OBJECTIVES

Pertussis and influenza are endemic infections and associated with relevant morbidity and mortality in newborns and young infants. The Swiss Federal Office of Public Health has recommended influenza vaccination since 2011 and pertussis vaccination in pregnancy (ViP) since 2013 and expanded to repetition in each pregnancy since 2017. ViP is safe and effective in preventing severe diseases, but implementation is a challenge. We hypothesized that the proportion of women receiving ViP is persistently low despite existing national recommendations. Our primary objective was to compare the proportion of pertussis and influenza vaccine recommendations for and its acceptance by pregnant women before and after an information campaign tailored to obstetricians. Secondly, we aimed to identify reasons for missing or declining ViP.

STUDY DESIGN

We conducted a prospective, single-center, single-arm implementation study in the maternity ward at the University Women's Hospital Basel. We performed standardized interviews with women hospitalized for postpartum care before (October to December 2019, Phase 1, n = 262) and after an information campaign (October to December 2020, Phase 2, n = 233) and compared categorical variables using chi-squared or Fisher's exact test and continuous variables using Whitney Mann U test.

RESULTS

We found no significant differences in the proportion of recommendation for pertussis ViP (80 % vs. 84 %, p = 0.25) and implementation (76 % vs. 78 %, p = 0.63) between Phase 1 and 2. Main reasons for missing or declining vaccinations were lack of recommendation (62.8 %) and safety concerns regarding the unborn child (17.7 %). In contrast, the proportion of recommendation for influenza ViP (45 % vs. 63 %, p < 0.001) and implementation (29 % vs. 43 %, p < 0.001) increased significantly.

CONCLUSION

Proactive recommendations by obstetricians play a key role in the implementation of ViP but is still insufficient in our setting. We believe that future efforts should aim to explore possible hurdles that impede recommendations by obstetricians for ViP. The focus should be on the needs and experiences of obstetricians in private practice, but also other health care professionals involved in care of pregnant women. Local campaigns do not seem effective enough, therefore national campaigns with new strategies are desirable.

Viral Pneumonia: From Influenza to COVID-19

Respiratory viruses are increasingly recognized as a cause of community-acquired pneumonia (CAP). The implementation of new diagnostic technologies has facilitated their identification, especially in vulnerable population such as immunocompromised and elderly patients and those with severe cases of pneumonia. In terms of severity and outcomes, viral pneumonia caused by influenza viruses appears similar to that caused by non-influenza viruses. Although several respiratory viruses may cause CAP, antiviral therapy is available only in cases of CAP caused by influenza virus or respiratory syncytial virus. Currently, evidence-based supportive care is key to managing severe viral pneumonia. We discuss the evidence surrounding epidemiology, diagnosis, management, treatment, and prevention of viral pneumonia.

An Observational Study on the Pharmacokinetics of Oseltamivir in Lactating Influenza Patients

Influenza infection may lead to serious complications in the postpartum period, therefore, oseltamivir treatment in these patients and their breastfed infants is of great importance. However, the pharmacokinetics of oseltamivir in postpartum lactating women with acute influenza infection, and the consequent infant exposure to oseltamivir are still unknown, and these data would help in assessing risk and the need for dose adjustment in breastfed infants. Six lactating women with influenza-like symptoms, at a standard dose of 75 mg oral oseltamivir twice daily for 5 days, were recruited in this phase IV clinical study during the 2011/2012 H1N1 pandemic seasons. Breast milk/colostrum and venous blood samples were taken at multiple timepoints, maternal urine samples were obtained from total output within the 12-hour observational period following the seventh dose of oseltamivir. Oseltamivir phosphate (OP) reached a maximum 69.5 ± 29.4 ng/mL concentration in breast milk, higher than that found in the plasma, and showed elimination within ~ 8 hours. Oseltamivir carboxylate (active metabolite of OP) showed a lower, nearly steady-state concentration in breast milk during the observational period (maximum plasma concentration (Cmax ) = 38.4 ± 12.9 ng/mL). Based on estimated daily milk consumption of exclusively breastfed infants, their calculated daily exposure is < 0.1% of the infant dose of oseltamivir for treatment of influenza as per marketing authorization. Here, we provide the first maternal breast milk pharmacokinetic data for oral multiple-dose oseltamivir in lactating patients with influenza and showed that its concentration in the breast milk is not sufficient to reach a therapeutic dose for breastfed infants.

Pregnant women's attitudes and behaviours towards antenatal vaccination against Influenza and COVID-19 in the Liverpool City Region, United Kingdom: Cross-sectional survey

Objectives

Influenza poses a serious health risk to pregnant women and their babies. Despite this risk, influenza vaccine uptake in pregnant women in the UK is less than 50%. Little is known about how COVID-19 affects pregnant women, but its management may affect attitudes and behaviours towards vaccination in pregnancy. The study objectives were to establish attitudes and knowledge of pregnant women towards influenza disease and influenza vaccination and to compare these to attitudes and knowledge about COVID-19 and COVID-19 vaccination.

Design

A cross-sectional survey was conducted using an online questionnaire distributed through local advertisement and social media outlets. Information was sought on attitudes and knowledge of influenza and COVID-19 and their respective vaccines.

Participants and setting

Pregnant women residing in Liverpool City Region, UK.

Results

Of the 237 respondents, 73.8% reported receiving an influenza vaccine. Over half (56.5%) perceived themselves to be at risk from influenza, 70.5% believed that if they got influenza, their baby would get ill, and 64.6% believed getting influenza could hurt their baby, 60.3% believed that the influenza vaccine would prevent their baby from getting ill, and 70.8% believed it would protect their baby. Only 32.9% of respondents stated they would receive the COVID-19 vaccine if it were available to them. However, 80.2% stated they would receive a COVID-19 vaccine if they were not pregnant. Most of the women stated that they would accept a vaccine if recommended to them by healthcare professionals.

Conclusions

Acceptance of the influenza and COVID-19 vaccines during pregnancy seems to be more related to the safety of the baby rather than the mother. Women perceived their child to be more at risk than themselves. Information about influenza and COVID-19 vaccine safety as well as healthcare provider recommendations play an important role in vaccine uptake in pregnant women.

Assessing the Presence of IgG Antibodies against Influenza Viruses in Neonates after Maternal Vaccination and Factors That May Affect the Transplacental Transfer

Special populations, particularly pregnant women, are uniquely susceptible to infectious diseases due to alterations in their immunological, respiratory, and cardiovascular systems during gestation. Influenza infections during the perinatal period have been associated with more severe maternal and perinatal outcomes, underscoring the critical importance of vaccination data for pregnant women. According to the World Health Organization (WHO), all pregnant women and those of childbearing age should receive the inactivated influenza vaccine, irrespective of their pregnancy stage. This study aimed to elucidate factors influencing neonatal antibody presence following maternal influenza vaccination. Conducted through convenience sampling in Athens, Greece, this study involved 78 pregnant women who received flu vaccinations. The participants completed questionnaires covering demographics, obstetric history, attitudes toward influenza vaccination, and knowledge about the influenza virus and pregnancy vaccination. Blood samples were collected from 83 neonates to assess IgG antibody presence. Five of the surveyed women had twin pregnancies. The statistical analysis employed IBM SPSS-Statistics version 26.0. This study revealed the presence of positive influenza A and B antibodies in neonates following maternal immunization. Furthermore, it identified factors such as the gestational week and timing of vaccination during pregnancy that influenced the transfer of antibodies from mother to fetus. These findings offer valuable insights for healthcare professionals to provide informed recommendations on influenza vaccination during pregnancy and empower expectant mothers to make informed decisions about the benefits of immunization.

Coverage and predictors of influenza and pertussis vaccination during pregnancy: a whole of population-based study

BACKGROUND

Respiratory infections including influenza and pertussis are associated with significant morbidity and mortality in mothers and newborns. Vaccination during pregnancy against influenza and pertussis is recommended for all women but data on uptake in Australia is limited.

METHODS

We conducted a retrospective population-based cohort study in Australia's largest state, New South Wales (NSW), using a Perinatal Data Collection (PDC). Data included demographic, pregnancy, and birth details including pertussis and influenza vaccination during pregnancy for all women giving birth between 01 January 2016 and 31 December 2020. We used descriptive statistics to assess uptake of influenza and pertussis vaccination during pregnancy and Poisson loglinear regression to estimate associations between maternal characteristics and vaccine receipt.

RESULTS

During 2016-2020, there were 477,776 births (mean maternal age 32.25 years). In 176,255 (36.9%) births the mother received both vaccines; 202,922 (42.5%) influenza and 315,620 (66.1%) pertussis vaccine. From 2016 to 2020, reported coverage increased from 26.7% to 58.7% for influenza and 43.1% to 78.8% for pertussis, respectively. After adjustment, characteristics associated with lower likelihood of receiving influenza and pertussis vaccination included: younger age (<30 years), being born in Australia/New Zealand, from lower socio-economic strata, having previous pregnancies, being later to first antenatal care, utilising the public hospital care model, smoking, having chronic hypertension and BMI > 25 kg/m2.

CONCLUSIONS

While reported coverage of both influenza and pertussis vaccine in birthing women in NSW has increased over time, disparities in coverage exist and they highlight areas where evidence-based interventions to improve maternal vaccination could be targeted.

Management of influenza - updated Swedish guidelines for antiviral treatment

Influenza causes seasonal epidemics of respiratory infection in all parts of the world. Manifestations of influenza range from mild upper to severe lower respiratory tract infection. Medical risk groups are defined by factors predisposing for development of severe disease and are recommended annual vaccination as a protective measure. The previous Swedish treatment guidelines for influenza were issued in 2011, and a review of current evidence was deemed relevant. An important reason to revisit the guidelines is the recent approval of a novel drug for influenza treatment, baloxavir. Updated Swedish evidence-based guidelines created by a group of experts from various research areas, for the management of influenza are presented here. The work has been made in collaboration with the Public Health Agency of Sweden and the Swedish Reference Group for AntiViral therapy (RAV). The updated guidelines include guidelines for diagnostics, treatment and prophylaxis in special groups, including management of pregnant women and children with influenza. A new section about infection control has been added. Pharmacological treatment is covered in detail with regards to indication and dosage. Additionally, drug resistance and environmental aspects are discussed.

Vaccine hesitancy and knowledge regarding maternal immunization among reproductive age women in central Italy: a cross sectional study

Background

Vaccination in pregnancy offers protection to the mother and the newborn. In Italy, influenza, pertussis, and COVID-19 vaccinations are recommended in pregnancy, but vaccination coverage is still far from the National Immunization Plan goals. We aimed to assess knowledge and attitude on maternal immunization in two groups of Italian women, in pregnancy and in reproductive age (non pregnant).

Methods

A cross sectional study on Italian childbearing age women gathering information on their knowledge on maternal immunization and attitudes to receiving influenza and pertussis vaccines in pregnancy was carried out at the University of Rome Tor Vergata, between September 2019 and February 2020. Logistic and multinomial regressions were chosen as statistical tests for our analysis.

Results

1,031 women participated in the survey by answering the questionnaire. Out of these, 553 (53.6%) women were pregnant, and 478 (46.4%) were in the reproductive age. 37% (204/553) of pregnant women and 41% (198/476) of non pregnant women are aware of the existence of an immunization plan for pregnant women in Italy. The group with age between 20 and 30, for both pregnant women and women in the reproductive age, has a better knowledge of vaccination in pregnancy. Working status is a variable associated with more awareness about vaccination during pregnancy only for pregnant women (OR = 2.34, p < 0.00001). Educational status, trimester of pregnancy and knowledge on the topic are associated with vaccine hesitancy in our multivariate analysis for pregnant women. In the reproductive age group women who had a previous pregnancy are more likely to be hesitant towards vaccination in pregnancy, on the other hand the one with a higher knowledge and educational status are more likely to get vaccinated.

Conclusions

The study highlights the persistent vaccine hesitancy among Italian women of reproductive age and pregnant women. Despite healthcare providers being identified as a reliable source of information, their recommendations alone are insufficient to overcome vaccine hesitancy. Factors such as employment status, educational level, pregnancy trimester, and knowledge about vaccinations during pregnancy influence vaccine hesitancy. Tailored educational interventions and communication campaigns targeting these areas can help reduce vaccine hesitancy and promote maternal immunization.

Influenza A virus infection during pregnancy causes immunological changes in gut-associated lymphoid tissues of offspring mice

Maternal influenza A virus (IAV) infection during pregnancy can affect offspring immune programming and development. Offspring born from influenza-infected mothers are at increased risk of neurodevelopmental disorders and have impaired respiratory mucosal immunity against pathogens. The gut-associated lymphoid tissue (GALT) represents a large proportion of the immune system in the body and plays an important role in gastrointestinal (GI) homeostasis. This includes immune modulation to antigens derived from food or microbes, gut microbiota composition, and gut-brain axis signaling. Therefore, in this study, we investigated the effect of maternal IAV infection on mucosal immunity of the GI tract in the offspring. There were no major anatomical changes to the gastrointestinal tract of offspring born to influenza-infected dams. In contrast, maternal IAV did affect the mucosal immunity of offspring, showing regional differences in immune cell profiles within distinct GALT. Neutrophils, monocytes/macrophages, CD4+ and CD8+ T cells infiltration was increased in the cecal patch offspring from IAV-infected dams. In the Peyer's patches, only activated CD4+ T cells were increased in IAV offspring. IL-6 gene expression was also elevated in the cecal patch but not in the Peyer's patches of IAV offspring. These findings suggest that maternal IAV infection perturbs homeostatic mucosal immunity in the offspring gastrointestinal tract. This could have profound ramifications on the gut-brain axis and mucosal immunity in the lungs leading to increased susceptibility to respiratory infections and neurological disorders in the offspring later in life.NEW & NOTEWORTHY Influenza A virus (IAV) infection during pregnancy is associated with changes in gut-associated lymphoid tissue (GALT) in the offspring in a region-dependent manner. Neutrophils and monocytes/macrophages were elevated in the cecal patch of offspring from infected dams. This increase in innate immune cell infiltration was not observed in the Peyer's patches. T cells were also elevated in the cecal patch but not in the Peyer's patches.

A colloidal gold test strip based on catalytic hairpin assembly for the clinical detection of influenza a virus nucleic acid

Influenza A epidemics, which occur annually in varying degrees worldwide, is a global challenge to healthcare facilities owing to several limitations of the current detection methods. Therefore, the development of a rapid, convenient, and economical method for the early diagnosis of influenza A will aid clinical treatment and epidemic control. Currently, most of the commonly used clinical rapid tests utilize colloidal gold test strips that detect specific influenza virus antigens but are limited by low sensitivity. Therefore, this study combined catalytic hairpin assembly (CHA) with colloidal gold immunochromatographic assay (GICA) to develop a highly sensitive and visual CHA-GICA test strip. Clinical sample analysis revealed that the sensitivity of the assay was 81.8% and 74% under optimal (35 °C) and room temperature (25 °C) conditions, respectively. In conclusion, this study developed a rapid nucleic acid assay for detecting influenza A virus with high sensitivity and specificity, which can improve the clinical detection of influenza A.

Vaccination against influenza in pregnant women in a maternity hospital in the Czech Republic in the season 2020-2021

OBJECTIVES

Pregnant women are among the priority groups to receive influenza vaccines in the Czech Republic since 2011, data on vaccination coverage are not yet available. The aim of the study was to determine the influenza vaccination coverage (IVC) and provide source data for further activities.

METHODS

A prospective observational study was performed in a large maternity hospital in Prague. The self-completed questionnaire was distributed to 5,475 pregnant women between September 1, 2020 and August 31, 2021. Questions included maternal sociodemographic characteristics, influenza vaccination status and sources of maternal vaccination recommendations during pregnancy.

RESULTS

A total of 4,617 completed questionnaires have been analysed. The median age of study participants (N = 4,592) was 33 years (range: 18-51 years). The majority (69.7%) of women had completed their university education, most women were childless (58.5%) or had one child (32.5%) before the start of the study. Less than 2% of women reported being vaccinated against influenza during their pregnancy (1.5%; 95% CI, 1.1-1.9%). Only 21% of women knew that it's possible to get vaccinated against influenza during pregnancy. Participants considered influenza vaccination in pregnancy as important (3.3%), useful (41.1%) and useless (44.4%). Out of 959 pregnant women who had information about influenza vaccination during pregnancy, only 6.9% were vaccinated, while among those who did not have this information, 0.1% were vaccinated during pregnancy (p < 0.001). The most frequent source of information was Internet, then media and a general practitioner.

CONCLUSIONS

The IVC during pregnancy in our study was extremely low. In order to improve IVC among pregnant women, it is necessary to increase awareness of recommendations and vaccination options among the public and professionals and incorporating vaccination recommendation in routine antenatal practice.

Inequity of antenatal influenza and pertussis vaccine coverage in Australia: the Links2HealthierBubs record linkage cohort study, 2012-2017

BACKGROUND

Pregnancy and early infancy are increased risk periods for severe adverse effects of respiratory infections. Aboriginal and/or Torres Strait Islander (respectfully referred to as First Nations) women and children in Australia bear a disproportionately higher burden of respiratory diseases compared to non-Indigenous women and infants. Influenza vaccines and whooping cough (pertussis) vaccines are recommended and free in every Australian pregnancy to combat these infections. We aimed to assess the equity of influenza and/or pertussis vaccination in pregnancy for three priority groups in Australia: First Nations women; women from culturally and linguistically diverse (CALD) backgrounds; and women living in remote areas or socio-economic disadvantage.

METHODS

We conducted individual record linkage of Perinatal Data Collections with immunisation registers/databases between 2012 and 2017. Analysis included generalised linear mixed model, log-binomial regression with a random intercept for the unique maternal identifier to account for clustering, presented as prevalence ratios (PR) and 95% compatibility intervals (95%CI).

RESULTS

There were 445,590 individual women in the final cohort. Compared with other Australian women (n = 322,848), First Nations women (n = 29,181) were less likely to have received both recommended antenatal vaccines (PR 0.69, 95% CI 0.67-0.71) whereas women from CALD backgrounds (n = 93,561) were more likely to have (PR 1.16, 95% CI 1.10-1.13). Women living in remote areas were less likely to have received both vaccines (PR 0.75, 95% CI 0.72-0.78), and women living in the highest areas of advantage were more likely to have received both vaccines (PR 1.44, 95% CI 1.40-1.48).

CONCLUSIONS

Compared to other groups, First Nations Australian families, those living in remote areas and/or families from lower socio-economic backgrounds did not receive recommended vaccinations during pregnancy that are the benchmark of equitable healthcare. Addressing these barriers must remain a core priority for Australian health care systems and vaccine providers. An extension of this cohort is necessary to reassess these study findings.

The association between maternal influenza vaccination during pregnancy and adverse birth outcomes in the United States: Pregnancy risk Assessment Monitoring System (PRAMS)

OBJECTIVE

Influenza vaccination during pregnancy is highly recommended. We examined the association between maternal influenza vaccination and adverse birth outcomes.

METHODS

This cross-sectional study used data from the Pregnancy Risk Assessment Monitoring System (PRAMS) during 2012-2017. The primary exposure was the receipt of influenza vaccination during pregnancy. Low birth weight (LBW), preterm birth (PTB), and small for gestational age (SGA) were the primary outcomes. We conducted multivariable logistic regression models to estimate the adjusted odds ratios (AOR) and 95% confidence intervals (CI). Covariates used to adjust confounding included maternal age, marital status, education, race and ethnicity, insurance status before pregnancy, and smoking status. For a subgroup in 2012-2015, we analyzed the association between influenza vaccination in each trimester and adverse birth outcomes.

RESULTS

During 2012-2017, compared with unvaccinated women, women vaccinated during pregnancy had a lower risk of LBW and PTB. During 2012-2015, maternal influenza vaccination in the 1st and 3rd trimesters was associated with a reduced risk of LBW and PTB, and vaccination in the 3rd trimester had a greater protective effect than in the 1st trimester. Influenza vaccination was not associated with SGA regardless of trimester.

CONCLUSIONS

Our findings suggest that influenza vaccination during pregnancy is a safe and effective way to protect newborns.

Effect of COVID-19 on antenatal care: experiences of medical professionals in the Netherlands

BACKGROUND

COVID-19 has greatly affected the delivery of all health care services globally. Antenatal care is one area of care that has been impacted, despite the fact that attending antenatal check-ups is essential for pregnant women and cannot be postponed. Little is known about how exactly ANC provision has changed in the Netherlands, or how the changes have impacted midwives and gynaecologists providing those services.

METHODS

This study used a qualitative research design to investigate changes in individual and national practice following the onset of the COVID-19 pandemic. The study involved a document analysis of protocols and guidelines for ANC provision to evaluate how those changed following the onset of the COVID-19 pandemic and semi-structured interviews with ANC care providers (i.e., gynaecologists and midwives).

RESULTS

Guidance was issued by multiple organizations, during the pandemic, on how to approach the risk of infection in pregnant women, recommending several changes to ANC to protect both pregnant women and ANC providers. Both midwives and gynaecologists reported changes in their practice. With less face-to-face consultations happening, digital technologies became critical in the care of pregnant women. Shorter and fewer visits were reported, with midwifery practices adjusting their guidelines further than hospitals. Challenges, with high workloads and lack of personal protective equipment were discussed.

CONCLUSIONS

The COVID-19 pandemic has had an immense impact on the health care system. This impact has had both negative and positive effects on the provision of ANC in the Netherlands. It is important to learn from the current COVID-19 pandemic and adapt ANC, as well as health care systems as a whole, to be better prepared for future health crises and ensure continuous provision of good quality care.

Surveillance Systems for Monitoring Vaccination Coverage with Vaccines Recommended for Pregnant Women, United States

Pregnant women* and their infants are at increased risk for serious influenza, pertussis, and COVID-19-related complications, including preterm birth, low-birth weight, and maternal and fetal death. The advisory committee on immunization practices recommends pregnant women receive tetanus-toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine during pregnancy, and influenza and COVID-19 vaccines before or during pregnancy. Vaccination coverage estimates and factors associated with maternal vaccination are measured by various surveillance systems. The objective of this report is to provide a detailed overview of the following surveillance systems that can be used to assess coverage of vaccines recommended for pregnant women: Internet panel survey, National Health Interview Survey, National Immunization Survey-Adult COVID Module, Behavioral Risk Factor Surveillance System, Pregnancy Risk Assessment Monitoring System, Vaccine Safety Datalink, and MarketScan. Influenza, Tdap, and COVID-19 vaccination coverage estimates vary by data source, and select estimates are presented. Each surveillance system differs in the population of pregnant women, time period, geographic area for which estimates can be obtained, how vaccination status is determined, and data collected regarding vaccine-related knowledge, attitudes, behaviors, and barriers. Thus, multiple systems are useful for a more complete understanding of maternal vaccination. Ongoing surveillance from the various systems to obtain vaccination coverage and information regarding disparities and barriers related to vaccination are needed to guide program and policy improvements.

Timing and temporal trends of influenza and pertussis vaccinations during pregnancy in three Australian jurisdictions: The Links2HealthierBubs population-based linked cohort study, 2012-2017

BACKGROUND

Antenatal inactivated influenza (IIV) and pertussis-containing vaccines (dTpa) offer protection against severe respiratory infections for pregnant women and infants <6 months of age. Both vaccines are recommended in pregnancy; however, little is known about temporal or jurisdictional trends and predictors of uptake.

AIMS

To identify gaps and predictors of IIV and/or dTpa vaccinations in Australian pregnancies from 2012 to 2017.

MATERIALS AND METHODS

We conducted a probabilistically linked, multi-jurisdictional population-based cohort study, drawing from perinatal data collections and immunisation databases. We used a generalised linear mixed model with a random effect term to account for clustering of multiple pregnancies within mothers, to calculate vaccination uptake, and identify predictors of uptake by maternal demographic, pregnancy, and health characteristics.

RESULTS

Of 591 868 unique pregnancies, IIV uptake was 15%, dTpa 27% and 12% received both vaccines. Pertussis vaccinations in First Nations pregnancies were 20% lower than non-Indigenous pregnancies; dTpa was strongly associated with IIV uptake (risk ratio (RR): 8.60, 95% CI 8.48-8.73). This trend was temporally and jurisdictionally consistent. First Nations women were more likely to have had IIV in pregnancy before the introduction of dTpa in the pregnancy program: (RR: 1.48, 95% CI 1.40-1.57), but less likely after dTpa implementation (RR: 0.78, 95% CI 0.76-0.80).

CONCLUSIONS

Inequity in vaccine uptake between First Nations and non-Indigenous pregnancies, and dismal rates of vaccination in pregnancy overall need urgent review, particularly before the next influenza pandemic or pertussis outbreak. If antenatal dTpa is driving IIV uptake, changes in antenatal healthcare practices are needed to ensure vaccines are offered equitably and optimally to protect against infection.

Hospital Admissions from the Emergency Department and Subsequent Critical Care Interventions for Influenza during Pregnancy

OBJECTIVE

The objectives of this study were to determine (1) whether obstetrical patients were more likely to be admitted from the emergency department (ED) for influenza compared with nonpregnant women, and (2) require critical care interventions once admitted.

STUDY DESIGN

Using data from the 2006 to 2011 Nationwide Emergency Department Sample, ED encounters for influenza for women aged 15 to 54 years without underlying chronic medical conditions were identified. Women were categorized as pregnant or nonpregnant using billing codes. Multivariable log linear models were fit to evaluate the relative risk of admission from the ED and the risk of intensive care unit (ICU)-level interventions including mechanical ventilation and central monitoring with pregnancy status as the exposure of interest. Measures of association were described with adjusted risk ratios (aRRs) with 95% confidence intervals (CIs).

RESULTS

We identified 15.9 million ED encounters for influenza of which 4% occurred among pregnant women. Pregnant patients with influenza were nearly three times as likely to be admitted as nonpregnant patients (aRR = 2.99, 95% CI: 2.94, 3.05). Once admitted, obstetric patients were at 72% higher risk of ICU-level interventions (aRR = 1.72, 95% CI: 1.61, 1.84). Of pregnant women admitted from the ED, 9.3% required ICU-level interventions such as mechanical ventilation or central monitoring. Older patients and those with Medicare were also at high risk of admission and ICU-level interventions (p < 0.01).

CONCLUSION

Pregnancy confers three times the risk of admission from the ED for influenza and pregnant women are significantly more likely to require ICU-level medical interventions compared with women of similar age. These findings confirm the significant disease burden from influenza in the obstetric population and the public health importance of reducing infection risk.

KEY POINTS

· Pregnancy confers three times the risk of admission from the ED for influenza.. · Pregnant women admitted with influenza are significantly more likely to require ICU-level care.. · Influenza represents a significant disease burden in the obstetric population.

Mild and asymptomatic influenza B virus infection among unvaccinated pregnant persons: Implication for effectiveness of non-pharmaceutical intervention and vaccination to prevent influenza

BACKGROUND

We estimated symptomatic and asymptomatic influenza infection frequency in community-dwelling unvaccinated pregnant persons to inform risk communication.

METHODS

We collected residue sera from multiple antenatal-care blood draws during October 2016-April 2017. We determined influenza infection as seroconversion with ≥ 4-fold rise in antibody titers between any two serum samples by improved hemagglutinin-inhibition assay including ether-treated B antigens. The serology data were linked to the results of nuclei acid testing (rRT-PCR) based on acute respiratory illness (ARI) surveillance.

RESULTS

Among all participants, 43 %(602/1384) demonstrated serology and/or rRT-PCR evidenced infection, and 44 %(265/602) of all infections were asymptomatic. ARI-associated rRT-PCR testing identified only 10 %(61/602) of total infections. Only 1 %(5/420) of the B Victoria cases reported ARI and had a rRT-PCR positive result, compared with 33 %(54/165) of the H3N2 cases. Among influenza ARI cases with multiple serum samples, 19 %(11/58) had seroconversion to a different subtype prior to the illness.

CONCLUSIONS

The incidence of influenza B infection in unvaccinated pregnant persons is under-estimated substantially. Non-pharmaceutical intervention may have suboptimal effectiveness in preventing influenza B transmission due to the less clinical manifestation compared to influenza A. The findings support maternal influenza vaccination to protect pregnant persons and reduce consequent household transmission.

Maternal and Neonatal Outcomes of COVID-19 Infection in Pregnancy

BACKGROUND

Limited data is available on the full spectrum of maternal COVID-19 infection in terms of pregnancy outcomes. The present study aimed to compare the maternal and neonatal outcomes of COVID-19 in infected and non-infected pregnant women.

METHODS

A dual-site retrospective cohort study was conducted in two tertiary hospitals in Isfahan, Iran. The sample included 104 infected and 210 non-infected hospitalized pregnant women. Odds ratios (OR) were estimated using multivariate logistic regression.

RESULTS

There were significant differences between COVID-19-infected and non-infected pregnant women regarding preterm labor (PTL) (odds ratio [OR]: 11.34, 95% confidence interval [CI]: 1.19-48.54, P=0.035); hospitalization days (OR: 7.21, 95% CI: 4.05-12.85, P≤0.001); cesarean section (CS) (OR: 4.76, 95% CI: 1.78-12.45, P=0.002); neonatal admission to neonatal intensive care unit (NICU) (OR: 1.28, 95% CI: 1.12-1.67, P=0.004); and neonatal respiratory distress (OR: 2.37, 95% CI: 1.02- 5.47, P=0.044). No significant association was found between COVID-19 infection and abortion (OR: 0.06, 95% CI: 0.01-1.45, P=0.084); stillbirth (OR: 1.84, 95% CI: 0.05-39.68, P=0.743); Apgar score (1 minute) (OR: 0.91, 95% CI: 0.74-1.13, P=0.382); Apgar score (5 minutes) (OR: 0.97, 95% CI: 0.81-1.18, P=0.765); and low birth weight (LBW) (OR: 4.76, 95% CI: 1.78-12.45, P=0.002).

CONCLUSION

PTL, CS, neonatal admission in NICU, neonatal respiratory distress, and hospitalization days were significantly higher in pregnant women with COVID-19 compared to those without infection.

Respiratory viruses: their importance and lessons learned from COVID-19

Respiratory virus infection can cause severe illnesses capable of inducing acute respiratory failure that can progress rapidly to acute respiratory distress syndrome (ARDS). ARDS is related to poor outcomes, especially in individuals with a higher risk of infection, such as the elderly and those with comorbidities, i.e. obesity, asthma, diabetes mellitus and chronic respiratory or cardiovascular disease. Despite this, effective antiviral treatments available for severe viral lung infections are scarce. The coronavirus disease 2019 (COVID-19) pandemic demonstrated that there is also a need to understand the role of airborne transmission of respiratory viruses. Robust evidence supporting this exists, but better comprehension could help implement adequate measures to mitigate respiratory viral infections. In severe viral lung infections, early diagnosis, risk stratification and prognosis are essential in managing patients. Biomarkers can provide reliable, timely and accessible information possibly helpful for clinicians in managing severe lung viral infections. Although respiratory viruses highly impact global health, more research is needed to improve care and prognosis of severe lung viral infections. In this review, we discuss the epidemiology, diagnosis, clinical characteristics, management and prognosis of patients with severe infections due to respiratory viruses.

Influenza Virus Infection during Pregnancy as a Trigger of Acute and Chronic Complications

Influenza A virus (IAV) infection during pregnancy disrupts maternal and fetal health through biological mechanisms, which are to date poorly characterised. During pregnancy, the viral clearance mechanisms from the lung are sub-optimal and involve hyperactive innate and adaptive immune responses that generate wide-spread inflammation. Pregnancy-related adaptations of the immune and the cardiovascular systems appear to result in delayed recovery post-viral infection, which in turn promotes a prolonged inflammatory phenotype, increasing disease severity, and causing maternal and fetal health problems. This has immediate and long-term consequences for the mother and fetus, with complications including acute cardiopulmonary distress syndrome in the mother that lead to perinatal complications such as intrauterine growth restriction (IUGR), and birth defects; cleft lip, cleft palate, neural tube defects and congenital heart defects. In addition, an increased risk of long-term neurological disorders including schizophrenia in the offspring is reported. In this review we discuss the pathophysiology of IAV infection during pregnancy and its striking similarity to other well-established complications of pregnancy such as preeclampsia. We discuss general features of vascular disease with a focus on vascular inflammation and define the "Vascular Storm" that is triggered by influenza infection during pregnancy, as a pivotal disease mechanism for short and long term cardiovascular complications.

Mapping the maternal vaccination journey and influencing factors for Māori women in Aotearoa New Zealand: a qualitative study

Introduction Uptake of maternal vaccinations (MVs) is suboptimal in Aotearoa New Zealand, particularly for Māori. Aim To describe Māori women's journeys regarding maternal pertussis and influenza vaccinations and explore influences on uptake. Methods Semi-structured interviews were conducted in Waikato, Aotearoa New Zealand, with pregnant or recently pregnant Māori women, and separately with Māori healthcare professionals (HCPs) to understand women's decisions regarding MVs and enablers and barriers to uptake. Results Nine women and nine HCPs were interviewed. Verbal communications from midwives, general practice and pharmacy strongly influenced women's journeys. Women's decisions appeared largely straight-forward, with influences including awareness, knowledge, underlying beliefs and previous MVs. Enablers for MV uptake included HCPs' discussions, pro-vaccination beliefs, and accessibility. Barriers for MV uptake included poverty (and transport), lack of awareness, insufficient knowledge of benefits, late presentation to the midwife and other commitments or challenges in the women's lives affecting prioritisation of the vaccine. Misconceptions, seasonality, and lower HCP emphasis impaired influenza vaccination uptake. Discussion With multiple barriers to accessing MVs, HCPs who see pregnant women are the primary resource to improve awareness, knowledge, and access through kōrero (discussions) with the woman and, where possible, being able to administer the vaccinations. These HCPs need to be well-informed, aware of likely concerns women may have and how to address them, encourage these discussions and preferably be trusted.

Protecting the Offspring, the Gift of Maternal Immunization: Current Status and Future Perspectives

Pregnancy is characterized by immunological alterations in pregnant women that permit the growth of a semi-allogenic fetus, resulting in greater susceptibility of childbearing women to infections. Furthermore, due to the immaturity of the immune system of neonates, a protection gap is present in early life, leaving neonates and infants vulnerable to infectious diseases with increased morbidity and mortality. Maternal immunization against influenza, pertussis, and, in the context of the COVID-19 pandemic, SARS-CoV-2 has been implemented in several countries, with beneficial effects on both the mother and the offspring. The main protective mechanism of vaccination during pregnancy is transplacental transfer of maternal antibodies. However, recent evidence has implied that the fetal immune system may be influenced beyond passive immunity. This review sheds light on the current status of the routinely administered vaccinations during pregnancy, focusing on the impact of maternal immunization on the priming of the fetal immune system and suggesting future perspectives for the optimization of vaccination strategies.

Placental Vascular and Inflammatory Findings from Pregnancies Diagnosed with Coronavirus Disease 2019: A Systematic Review and Meta-analysis

We aimed to perform a meta-analysis of the literature concerning histopathologic findings in the placentas of women with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection during pregnancy. Searches for articles in English included PubMed, Web of Science, Google Scholar, and reference lists (up to April 2021). Studies presenting data on placental histopathology according to the Amsterdam Consensus Group criteria in SARS-CoV-2 positive and negative pregnancies were identified. Lesions were categorized into: maternal and fetal vascular malperfusion (MVM and FVM, respectively), acute placental inflammation with maternal and fetal inflammatory response (MIR and FIR, respectively), chronic inflammatory lesions (CILs), and increased perivillous fibrin deposition (PVFD). A total of 15 studies reporting on 19,025 placentas, n = 699 of which were derived from women who were identified as being infected with SARS-CoV-2 and 18,326 as SARS-CoV-2-negative controls, were eligible for analysis. No significant difference in incidence of MVM (odds ratio [OR]: 1.18, 95% confidence interval [CI]: 0.73-1.90), FVM (OR: 1.23, 95% CI: 0.63-2.42), MIR (OR: 0.66, 95% CI: 0.29-1.52) or FIR (OR: 0.85, 95% CI: 0.44-1.63), and CILs (OR: 0.97, 95% CI: 0.55-1.72) was found between placentae from gravida identified as being SARS-CoV-2 infected. However, placenta from gravida identified as being infected with SARS-CoV-2 were associated with significantly increased occurrence of PVFD (OR: 2.77, 95% CI: 1.06-7.27). After subgroup analyses based on clinical severity of COVID-19 infection, no significant difference was observed in terms of reported placental pathology between symptomatic or asymptomatic SARS-CoV-2 gravidae placenta. Current evidence based on the available literature suggests that the only pathologic finding in the placentae of women who are pregnant identified as having been infected with SARS-CoV-2 was an increased prevalence of PVFD. KEY POINTS: · No association between SARS-CoV-2 and maternal or fetal placental malperfusion.. · No association between SARS-CoV-2 and maternal or fetal inflammatory response.. · SARS-CoV-2 is associated with increased perivillous fibrin deposition in placenta..

Examining the impact of trimester of diagnosis on COVID-19 disease progression in pregnancy

BACKGROUND

COVID-19 infection is associated with increased morbidity in pregnancy and adverse maternal and neonatal outcomes. Little is currently known about how the timing of infection during pregnancy affects these outcomes.

OBJECTIVE

This study aimed to evaluate the effect of trimester of COVID-19 infection on disease progression and severity in pregnant patients.

STUDY DESIGN

This was a prospective cohort study of pregnant patients diagnosed with COVID-19 infection who delivered at a single urban hospital. Universal testing for SARS-CoV-2 was performed at hospital admission and for symptomatic patients in inpatient, emergency department, and outpatient settings. Disease severity was defined as asymptomatic, mild, moderate, severe, or critical on the basis of National Institutes of Health criteria. We evaluated disease progression from asymptomatic to symptomatic infection and from asymptomatic or mild infection to moderate, severe, or critical illness, and stratified by trimester of COVID-19 diagnosis. Primary outcomes included progression of COVID-19 disease severity and a composite obstetrical outcome, which included delivery at <37 weeks, preeclampsia with severe features, abruption, excess blood loss at delivery (>500 mL for vaginal or >1000 mL for cesarean delivery), and stillbirth.

RESULTS

From March 18, 2020 to September 30, 2021, 1326 pregnant patients were diagnosed with COVID-19 and delivered at our institution, including 103 (8%) first-, 355 (27%) second-, and 868 (65%) third-trimester patients. First-trimester patients were older and had more medical comorbidities; 86% of patients in all trimesters were Hispanic. Among patients admitted within 14 days of a positive test, 3 of 18 (17%) first-trimester, 20 of 47 (43%) second-trimester, and 34 of 574 (6%) third-trimester patients were admitted for the indication of COVID-19 illness. Across all trimesters, 1195 (90%) of 1326 COVID-19 infections were asymptomatic or mild, and 45 (10%) of 436 initially asymptomatic patients developed symptoms. Of patients with asymptomatic or mild symptoms at diagnosis, 4 (4%) of 93 first-, 18 (5%) of 337 second-, and 49 (6%) of 836 third-trimester patients developed moderate, severe, or critical illness (P=.80). There was no significant difference in composite obstetrical outcome with respect to trimester of COVID-19 diagnosis (24% first-trimester, 28% second-trimester, 28% third-trimester patients; P=.69).

CONCLUSION

Moderate, severe, or critical illness develops in almost 10% of pregnant patients. The frequency of COVID-19 disease progression in pregnancy does not differ by trimester of diagnosis.

The influence of COVID-19 pandemic on intrauterine fetal demise and possible vertical transmission of SARS-CoV-2

OBJECTIVE

The impact of COVID-19 on intrauterine fetal demise (IUFD) and vertical transmission of the SARS-CoV-2 from the mother to the fetus are crucial issues of the COVID-19 pandemic. In the current study, we aimed to detect the pandemic's influence on the IUFD and evaluate the vertical transmission of the SARS-CoV-2 through analysis of placental tissues collected from PCR positive women with IUFD above 20 weeks of gestation.

MATERIALS AND METHODS

The pregnant women above 20 weeks of gestation and had a fetus intrauterine demised during pandemic were included in the study. The pregnant women screened for COVID-19. Vertical transmission searched from placental tissues of COVID-19 positive women by RT-PCR tests for the presence of SARS-CoV-2 RNA. The number of IUFD before the pandemic and during the pandemic compared to assess the influence of the COVID-19 pandemic on the IUFD ratio.

RESULTS

Among 138 pregnant women with IUFD, 100 of them could screen for COVID-19 status. RT-PCR test results of 6 of the screened pregnant women were positive for SARS-CoV-2. Placental tissues of these six women were analyzed, and one test result was positive for SARS-CoV-2 RNA. The IUFD ratio was significantly increased during the pandemic.

CONCLUSION

It is clear that COVID-19 increases the IUFD ratio. Previous data for vertical transmission of SARS-CoV-2 during the second trimester is limited. We present the third case of literature that has positive placental results for SARS-CoV-2 RNA in the second trimester of pregnancy.

Multi-decade national cohort identifies adverse pregnancy and birth outcomes associated with acute respiratory illness hospitalisations during the influenza season

BACKGROUND

Despite the World Health Organization (WHO) recommendation that pregnant women be prioritised for seasonal influenza vaccination, coverage in the Western Pacific Region remains low. Our goal was to provide additional data for the Western Pacific Region about the value of maternal influenza vaccination to pregnant women and their families.

METHODS

We conducted a 16-year retrospective cohort to evaluate risks associated with influenza-associated maternal acute respiratory infection (ARI) in New Zealand. ARI hospitalisations during the May to September influenza season were identified using select ICD-10-AM primary and secondary discharge codes from chapter J00-J99 (diseases of the respiratory system). Cox proportional hazards models were used to calculate crude and adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).

RESULTS

We identified 822,391 pregnancies among New Zealand residents between 2003 and 2018; 5095 (0.6%) had ≥1 associated ARI hospitalisation during the influenza season; these pregnancies were at greater risk of preterm birth (aHR 1.50, 95% CI 1.39-1.61) and low birthweight (aHR 1.64, 95% CI 1.51-1.79) than pregnancies without such hospitalisations. We did not find an association between maternal ARI hospitalisation and fetal death (aHR 0.96, 95% CI 0.69-1.34) during the influenza season. Maternal influenza vaccination was associated with reduced risk of preterm birth (aHR 0.79, 95% CI 0.77-0.82), low birthweight (aHR 0.87, 95% CI 0.83-0.90) and fetal death (aHR 0.50%, 95% CI 0.44-0.57).

CONCLUSION

In this population-based cohort, being hospitalised for an ARI during the influenza season while pregnant was a risk factor for delivering a preterm or a low birthweight infant and vaccination reduced this risk.

Association between social vulnerability and COVID-19 vaccination hesitancy and vaccination in pregnant and postpartum individuals

OBJECTIVE

To evaluate the association of community-level social vulnerability with COVID-19 vaccine hesitancy and vaccination among pregnant and postpartum individuals.

METHODS

Prospective cohort study assessing COVID-19 vaccine hesitancy among pregnant and postpartum individuals. We performed a baseline survey on COVID-19 vaccine hesitancy from 03/22/21 to 04/02/21, and a follow-up survey on COVD-19 vaccination status 3- to 6-months later. The primary exposure was the Centers for Disease Control and Prevention SVI (Social Vulnerability Index), measured in quartiles. Higher SVI quartiles indicated greater community-level social vulnerability with the lowest quartile (quartile 1) as the referent group. The primary outcome was COVID-19 vaccine hesitancy on the baseline survey (uncertainty or refusal of the vaccine), and the secondary outcome was self-report of not being vaccinated (unvaccinated) for COVID-19 on the follow-up survey.

RESULTS

Of 456 assessed individuals, 46% reported COVID-19 vaccine hesitancy on the baseline survey; and of 290 individuals (290/456, 64%) who completed the follow-up survey, 48% (140/290) were unvaccinated. The frequency of baseline vaccine hesitancy ranged from 25% in quartile 1 (low SVI) to 68% in quartile 4 (high SVI), and being unvaccinated at follow-up ranged from 29% in quartile 1 to 77% in quartile 4. As social vulnerability increased, the risk of COVID-19 vaccine hesitancy at baseline increased (quartile 2 aRR (adjusted relative risk): 1.46; 95% CI:0.98 to 2.19; quartile 3 aRR: 1.86; 95% CI:1.28 to 2.71; and quartile 4 aRR: 2.24; 95% CI:1.56 to 3.21), as did the risk of being unvaccinated at follow-up (quartile 2 aRR: 1.00; 95% CI:0.66 to 1.51; quartile 3 aRR: 1.68; 95% CI:1.17 to 2.41; and quartile 4 aRR: 1.82; 95% CI:1.30 to 2.56).

CONCLUSIONS

Pregnant and postpartum individuals living in an area with higher community-level social vulnerability were more likely to report COVID-19 vaccine hesitancy and subsequently to be unvaccinated at follow-up.

At the crux of maternal immune activation: Viruses, microglia, microbes, and IL-17A

Inflammation during prenatal development can be detrimental to neurodevelopmental processes, increasing the risk of neuropsychiatric disorders. Prenatal exposure to maternal viral infection during pregnancy is a leading environmental risk factor for manifestation of these disorders. Preclinical animal models of maternal immune activation (MIA), established to investigate this link, have revealed common immune and microbial signaling pathways that link mother and fetus and set the tone for prenatal neurodevelopment. In particular, maternal intestinal T helper 17 cells, educated by endogenous microbes, appear to be key drivers of effector IL-17A signals capable of reaching the fetal brain and causing neuropathologies. Fetal microglial cells are particularly sensitive to maternally derived inflammatory and microbial signals, and they shift their functional phenotype in response to MIA. Resulting cortical malformations and miswired interneuron circuits cause aberrant offspring behaviors that recapitulate core symptoms of human neurodevelopmental disorders. Still, the popular use of "sterile" immunostimulants to initiate MIA has limited translation to the clinic, as these stimulants fail to capture biologically relevant innate and adaptive inflammatory sequelae induced by live pathogen infection. Thus, there is a need for more translatable MIA models, with a focus on relevant pathogens like seasonal influenza viruses.

Maternal and neonatal immune response to SARS-CoV-2, IgG transplacental transfer and cytokine profile

SARS-CoV-2 infected pregnant women are at increased risk of severe COVID-19 than non-pregnant women and have a higher risk of adverse pregnancy outcomes like intrauterine/fetal distress and preterm birth. However, little is known about the impact of SARS-CoV-2 infection on maternal and neonatal immunological profiles. In this study, we investigated the inflammatory and humoral responses to SARS-CoV-2 in maternal and cord blood paired samples. Thirty-six pregnant women were recruited at delivery at Hospital Sant Joan de Déu, Barcelona, Spain, between April-August 2020, before having COVID-19 available vaccines. Maternal and pregnancy variables, as well as perinatal outcomes, were recorded in questionnaires. Nasopharyngeal swabs and maternal and cord blood samples were collected for SARS-CoV-2 detection by rRT-PCR and serology, respectively. We measured IgM, IgG and IgA levels to 6 SARS-CoV-2 antigens (spike [S], S1, S2, receptor-binding domain [RBD], nucleocapsid [N] full-length and C-terminus), IgG to N from 4 human coronaviruses (OC43, HKU1, 229E and NL63), and the concentrations of 30 cytokines, chemokines and growth factors by Luminex. Mothers were classified as infected or non-infected based on the rRT-PCR and serology results. Sixty-four % of pregnant women were infected with SARS-CoV-2 (positive by rRT-PCR during the third trimester and/or serology just after delivery). None of the newborns tested positive for rRT-PCR. SARS-CoV-2 infected mothers had increased levels of virus-specific antibodies and several cytokines. Those with symptoms had higher cytokine levels. IFN-α was increased in cord blood from infected mothers, and in cord blood of symptomatic mothers, EGF, FGF, IL-17 and IL-15 were increased, whereas RANTES was decreased. Maternal IgG and cytokine levels showed positive correlations with their counterparts in cord blood. rRT-PCR positive mothers showed lower transfer of SARS-CoV-2-specific IgGs, with a stronger effect when infection was closer to delivery. SARS-CoV-2 infected mothers carrying a male fetus had higher antibody levels and higher EGF, IL-15 and IL-7 concentrations. Our results show that SARS-CoV-2 infection during the third trimester of pregnancy induces a robust antibody and cytokine response at delivery and causes a significant reduction of the SARS-CoV-2-specific IgGs transplacental transfer, with a stronger negative effect when the infection is closer to delivery.