Characteristics and Outcomes of Hospitalized Pregnant Women With Influenza, 2010 to 2019 : A Repeated Cross-Sectional Study

Adverse events affecting recovery from seasonal influenza vaccination in the hypertensive population: A population-based pharmacovigilance analysis

Seasonal influenza vaccination is crucial for preventing influenza and its complications. Data from the United States Vaccine Adverse Event Reporting System (VAERS) indicate a higher proportion of adverse events (AEs) after influenza vaccination in hypertensive people. However, there is limited evidence on AEs in hypertensive people following seasonal influenza vaccination. We identified 4647 individuals aged 18 years or older with a history of hypertension who received seasonal influenza vaccination and 6380 seasonal influenza-vaccine-induced AEs between 1 January 2013 and 23 June 2023 from VAERS. We identified two groups for comparison: recovery and no recovery from seasonal influenza-vaccine-induced AEs. Propensity score matching (PSM) was performed to adjust for potential confounding factors, including demographic characteristics (age, sex, and region) and season of onset. Cox regression analysis was used to calculate the risk ratio of reported adverse events (AEs) that affected recovery after seasonal influenza vaccination. Most AEs were nonserious and occurred within 48 hours. The most common AEs were general disorders and administration site conditions (therapeutic and non-therapeutic responses, inflammation) and musculoskeletal and connective tissue disorders (musculoskeletal and connective tissue pain and discomfort, bursal disorders, joint-related signs, and symptoms). All three types of seasonal influenza vaccines were associated with injection site reactions (47.07% trivalent influenza vaccine [TIA], hazard ratio, HR 2.04, 95% confidence interval, CI 1.22-3.40; 20.00% quadrivalent influenza vaccine [QIA], HR 2.81, 95% CI, 1.81-4.37; 67.48% influenza vaccine, unknown manufacturer [FLUX], HR 2.83, 95% CI, 1.12-7.15) and were the AEs affecting the largest proportion of delayed recoveries in the hypertensive population. Potential AEs following seasonal influenza vaccination may affect the recovery of the hypertensive population. The majority of AEs reported were general disorders, predominantly injection site reactions, and nonserious.

Maternal oxygenation and fetal-neonatal mortality among patients with COVID-19 requiring advanced respiratory support in ICU: A multicenter prospective cohort study

OBJECTIVE

To explore the association of maternal characteristics, oxygenation, and mechanical ventilatory parameters with fetal and neonatal outcomes.

METHODS

The present study was a multicenter, binational (Argentina/Colombia), prospective, cohort study, conducted in 21 intensive care units (ICUs) and including pregnant or postpartum patients with COVID-19 pneumonia requiring advanced respiratory support and their fetuses/neonates. Advanced respiratory support was defined as high-flow nasal cannula (HFNC), non-invasive ventilation (NIV) or invasive mechanical ventilation (IMV).

RESULTS

A total of 91 patients were admitted to 21 ICUs: 63 (69%) antepartum and 28 (31%) postpartum. Among those admitted antepartum (63), delivery was induced in 43 (68.3%), being the reasons mostly maternal (28/43; 65.1%). Of 71 births, 64 (90%) were preterm. A total of 14 fetal/neonatal losses (14/91;15.4%) occurred. The main differences between patients whose fetuses/neonates survived versus those who did not survive were in APACHE II (12 [7-15] vs. 16.5 [14-20]; P = 0.003), SOFA24 (4 [3-5] vs. 6.5 [5-8]; P = 0.001), gestational age at delivery (32.9 ± 3 vs. 27.6 ± 6.2; P = 0.014), acute respiratory distress syndrome (54 [70.1%] vs. 14 [100%]; P = 0.011), septic shock (26 [33.8%] vs. 9 [64.3%]; P = 0.031), IMV (55 [71.4%] vs. 14 [100%]; P = 0.019) and plateau pressure before delivery (23 [21-26] vs. 28 [27-30]; P = 0.019). The incidence of fetal/neonatal mortality among 47 pregnant patients requiring IMV with SpO2 < 95% versus SpO2 >95% before intubation was 12/35 (34.28%) versus 1/12 (8.33%), respectively; P = 0.163. The incidence of fetal/neonatal mortality among those with SpO2 <95% versus SpO2 >95% before delivery was 5/18 (27.77%) versus 8/29 (25.58%), respectively; P = 0.999.

CONCLUSION

The vast majority of births were preterm. Among patients admitted antepartum, most deliveries were induced for maternal reasons. Fetal/neonatal losses were associated with gestational age at delivery, maternal severity of illness on admission and certain ventilatory parameters but not with maternal oxygenation, as is commonly the focus in these patients.

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.

Timing of Influenza Antiviral Therapy and Risk of Death in Adults Hospitalized With Influenza-Associated Pneumonia, Influenza Hospitalization Surveillance Network (FluSurv-NET), 2012-2019

BACKGROUND

Pneumonia is common in adults hospitalized with laboratory-confirmed influenza, but the association between timeliness of influenza antiviral treatment and severe clinical outcomes in patients with influenza-associated pneumonia is not well characterized.

METHODS

We included adults aged ≥18 years hospitalized with laboratory-confirmed influenza and a discharge diagnosis of pneumonia over 7 influenza seasons (2012-2019) sampled from a multistate population-based surveillance network. We evaluated 3 treatment groups based on timing of influenza antiviral initiation relative to admission date (day 0, day 1, days 2-5). Baseline characteristics and clinical outcomes were compared across groups using unweighted counts and weighted percentages accounting for the complex survey design. Logistic regression models were generated to evaluate the association between delayed treatment and 30-day all-cause mortality.

RESULTS

A total of 26 233 adults were sampled in the analysis. Median age was 71 years and most (92.2%) had ≥1 non-immunocompromising condition. Overall, 60.9% started antiviral treatment on day 0, 29.5% on day 1, and 9.7% on days 2-5 (median, 2 days). Baseline characteristics were similar across groups. Thirty-day mortality occurred in 7.5%, 8.5%, and 10.2% of patients who started treatment on day 0, day 1, and days 2-5, respectively. Compared to those treated on day 0, adjusted odds ratio for death was 1.14 (95% confidence interval [CI], 1.01-1.27) in those starting treatment on day 1 and 1.40 (95% CI, 1.17-1.66) in those starting on days 2-5.

CONCLUSIONS

Delayed initiation of antiviral treatment in patients hospitalized with influenza-associated pneumonia was associated with higher risk of death, highlighting the importance of timely initiation of antiviral treatment at admission.

The burden, pathogenesis, clinical outcomes, and treatment of common respiratory virus infections during pregnancy

Respiratory illnesses due to respiratory virus infections disproportionately impact pregnant individuals and their infants, leading to significant morbidity and mortality globally. Data describing the incidence and impact of these infections in pregnancy is sparse and more common for influenza and now severe acute respiratory syndrome coronavirus 2 with less data available on other respiratory virus infections in pregnancy. This lack of data is a result of limited prospective surveillance and issues surrounding the calculations of seroprevalence, as well as disproportionately low funding for reproductive health research. In this review article, we aimed to summarize available data on respiratory virus infections in pregnancy and identify gaps in the published literature.

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

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

Web-based intervention for improving influenza vaccination in pregnant women: a cost-effectiveness analysis

A website with vaccine information and interactive social media was reported to improve maternal influenza vaccine uptake. This study aimed to evaluate cost-effectiveness of a web-based intervention on influenza vaccine uptake among pregnant women from the perspective of US healthcare providers. A one-year decision-analytic model estimated outcomes in a hypothetical cohort of pregnant women with: (1) website with vaccine information and interactive social media (intervention group), and (2) usual care (usual care group). Primary measures included influenza infection, influenza-related hospitalization, mortality, direct medical cost, and quality-adjusted life-year (QALY) loss. In base-case analysis, intervention group reduced cost (by USD28), infection (by 28 per 1,000 pregnant women), hospitalization (by 1.226 per 1,000 pregnant women), mortality (by 0.0036 per 1,000 pregnant women), and saved 0.000305 QALYs versus usual care group. Relative improvement of vaccine uptake by the intervention and number of pregnant women in the healthcare system were two influential factors identified in deterministic sensitivity analysis. The intervention was cost-effective in 99.5% of 10,000 Monte Carlo simulations (at willingness-to-pay threshold 50,000 USD/QALY). A website with vaccine information and interactive social media to promote influenza vaccination for pregnant women appears to reduce direct medical costs and gain QALYs from the perspective of US healthcare providers.

Predictors of mental health among U.S. adults during COVID-19 early pandemic, mid- pandemic, and post-vaccine eras

BACKGROUND

A collective trauma like COVID-19 impacts individuals differently due to socio-contextual and individual characteristics. Younger adults, minorities, affiliates of certain political parties, and residents of some regions of the United States reported experiencing poorer mental health during the pandemic. Being diagnosed with COVID-19, or losing a friend/family to it, was related to more adverse mental health symptoms. While the negative impact of COVID-19 on health outcomes has been studied, mental health changes during this pandemic need further exploration.

METHODS

In a study of 8,612 U.S. households, using three surveys collected from a nationally representative panel between May 2020 and October 2021, using a repeated cross-sectional design, a linear mixed effect regression model was performed to investigate factors associated with the mental health status, based on the Mental Health Inventory-5, of individuals throughout different phases of the COVID-19 pandemic, and whether an improvement over time, especially after vaccines became available, was observed.

RESULTS

An overall improvement in mental health was observed after vaccines became available. Individuals with no COVID-related death in their household, those not wearing masks, those identifying as members of the Republican Party, race/ethnicities other than Asian, men, older adults, and residents of the South were less likely than others to report mental health challenges.

CONCLUSIONS

Our results highlight the need for widespread mental health interventions and health promotion to address challenges during the COVID-19 pandemic and beyond. Due to the worse mental health observed among Asians, younger adults, women, low-income families, those with a higher level of concern for COVID-19, people who lost someone to COVID-19, and/or individuals with histories of opioid use disorder and criminal legal involvement, over the period of this study, targeted attention needs to be given to the mental health of these groups.

Severity of influenza-associated hospitalisations by influenza virus type and subtype in the USA, 2010-19: a repeated cross-sectional study

BACKGROUND

Influenza burden varies across seasons, partly due to differences in circulating influenza virus types or subtypes. Using data from the US population-based surveillance system, Influenza Hospitalization Surveillance Network (FluSurv-NET), we aimed to assess the severity of influenza-associated outcomes in individuals hospitalised with laboratory-confirmed influenza virus infections during the 2010-11 to 2018-19 influenza seasons.

METHODS

To evaluate the association between influenza virus type or subtype causing the infection (influenza A H3N2, A H1N1pdm09, and B viruses) and in-hospital severity outcomes (intensive care unit [ICU] admission, use of mechanical ventilation or extracorporeal membrane oxygenation [ECMO], and death), we used FluSurv-NET to capture data for laboratory-confirmed influenza-associated hospitalisations from the 2010-11 to 2018-19 influenza seasons for individuals of all ages living in select counties in 13 US states. All individuals had to have an influenza virus test within 14 days before or during their hospital stay and an admission date between Oct 1 and April 30 of an influenza season. Exclusion criteria were individuals who did not have a complete chart review; cases from sites that contributed data for three or fewer seasons; hospital-onset cases; cases with unidentified influenza type; cases of multiple influenza virus type or subtype co-infection; or individuals younger than 6 months and ineligible for the influenza vaccine. Logistic regression models adjusted for influenza season, influenza vaccination status, age, and FluSurv-NET site compared odds of in-hospital severity by virus type or subtype. When missing, influenza A subtypes were imputed using chained equations of known subtypes by season.

FINDINGS

Data for 122 941 individuals hospitalised with influenza were captured in FluSurv-NET from the 2010-11 to 2018-19 seasons; after exclusions were applied, 107 941 individuals remained and underwent influenza A virus imputation when missing A subtype (43·4%). After imputation, data for 104 969 remained and were included in the final analytic sample. Averaging across imputed datasets, 57·7% (weighted percentage) had influenza A H3N2, 24·6% had influenza A H1N1pdm09, and 17·7% had influenza B virus infections; 16·7% required ICU admission, 6·5% received mechanical ventilation or ECMO, and 3·0% died (95% CIs had a range of less than 0·1% and are not displayed). Individuals with A H1N1pdm09 had higher odds of in-hospital severe outcomes than those with A H3N2: adjusted odds ratios (ORs) for A H1N1pdm09 versus A H3N2 were 1·42 (95% CI 1·32-1·52) for ICU admission; 1·79 (1·60-2·00) for mechanical ventilation or ECMO use; and 1·25 (1·07-1·46) for death. The adjusted ORs for individuals infected with influenza B versus influenza A H3N2 were 1·06 (95% CI 1·01-1·12) for ICU admission, 1·14 (1·05-1·24) for mechanical ventilation or ECMO use, and 1·18 (1·07-1·31) for death.

INTERPRETATION

Despite a higher burden of hospitalisations with influenza A H3N2, we found an increased likelihood of in-hospital severe outcomes in individuals hospitalised with influenza A H1N1pdm09 or influenza B virus. Thus, it is important for individuals to receive an annual influenza vaccine and for health-care providers to provide early antiviral treatment for patients with suspected influenza who are at increased risk of severe outcomes, not only when there is high influenza A H3N2 virus circulation but also when influenza A H1N1pdm09 and influenza B viruses are circulating.

FUNDING

The US Centers for Disease Control and Prevention.

Pregnancy-induced differential expression of SARS-CoV-2 and influenza a viral entry factors in the lower respiratory tract

Despite differences in the clinical presentation of coronavirus disease-19 and pandemic influenza in pregnancy, fundamental mechanistic insights are currently lacking because of the difficulty in recruiting critically ill pregnant subjects for research studies. Therefore, to better understand host-pathogen interaction during pregnancy, we performed a series of foundational experiments in pregnant rats at term gestation to assess the expression of host entry factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A virus (IAV) and genes associated with innate immune response in the lower respiratory tract. We report that pregnancy is characterized by a decrease in host factors mediating SARS-CoV-2 entry and an increase in host factors mediating IAV entry. Furthermore, using flow cytometric assessment of immune cell populations and immune provocation studies, we show an increased prevalence of plasmacytoid dendritic cells and a Type I interferon-biased environment in the lower respiratory tract of pregnancy, contrary to the expected immunological indolence. Our findings, therefore, suggest that the dissimilar clinical presentation of COVID-19 and pandemic influenza A in pregnancy could partly be due to differences in the extent of innate immune activation from altered viral tropism and indicate the need for comparative mechanistic investigations with live virus studies.

Local immune recognition of trophoblast in early human pregnancy: controversies and questions

The role of the maternal immune system in reproductive success in humans remains controversial. Here we focus on the events that occur in the maternal decidua during the first few weeks of human pregnancy, because this is the site at which maternal leukocytes initially interact with and can recognize fetal trophoblast cells, potentially involving allorecognition by both T cells and natural killer (NK) cells. NK cells are the dominant leukocyte population in first-trimester decidua, and genetic studies point to a role of allorecognition by uterine NK cells in establishing a boundary between the mother and the fetus. By contrast, definitive evidence that allorecognition by decidual T cells occurs during the first trimester is lacking. Thus, our view is that during the crucial period when the placenta is established, damaging T cell-mediated adaptive immune responses towards placental trophoblast are minimized, whereas NK cell allorecognition contributes to successful implantation and healthy pregnancy.

Acute Respiratory Distress Syndrome in Pregnancy: Updates in Principles and Practice

Acute respiratory failure occurs in 0.05% to 0.3% of pregnancies and is precipitated by pulmonary and nonpulmonary insults. Acute respiratory distress syndrome (ARDS) is the rapid onset of hypoxemic respiratory failure associated with bilateral pulmonary opacities on chest imaging attributed to noncardiogenic pulmonary edema. The pathophysiological features of ARDS include hypoxemia, diminished lung volumes, and decreased lung compliance. While there is a paucity of data concerning ARDS in the pregnant individual, management principles do not vary significantly between pregnant and nonpregnant patients. The following review will discuss the diagnosis and management of the pregnant patient with ARDS.

Prevalence and gender disparity of those who screen positive for depression in China by the classification of the employer and industry: a cross-sectional, population-based study

BACKGROUND

The important role of mental health in sustainable economic development is gradually being recognized. This study aimed to evaluate the prevalence and gender disparity of those who screen positive for depression in China by the employer and industrial classification.

METHODS

We used data from a nationally representative survey, the China Family Panel Studies. Depression was judged by the Centre for Epidemiologic Studies Depression Scale. Employer classifications were categorized according to the local characteristics of Mainland China. Industrial classifications were defined using level-1 of the China version of the International Standard Industrial Classification of All Economic Activities. Weighted logistic regressions were fitted to estimate the gender disparities, controlling for confounders.

RESULTS

Forty eight thousand six hundred twenty eight adults were included. 18.7% (95%CI 18.1-19.4) of sampled adults were screened positive for depression symptoms, with 16.6% (95%CI 15.8-17.5) in males vs 21.0% (95%CI 20.1-22.0) in females. By classification of the employer, the prevalence was lowest among those employed by Government/party organisations (11.8%, 95%CI 8.9-15.4), and highest in those self-employed (21.8%, 95%CI 20.8-22.9); the gender disparity was mainly found in those employed by Sole proprietorship (Adjusted odds ratio [AOR] = 1.95, 95%CI 1.19-3.19) and Private enterprise (AOR = 1.34, 95%CI 1.13-1.59), as well as those self-employed (AOR = 1.49, 95%CI 1.3-1.17). By industrial classification, the prevalence was lowest among those who worked in the industry of Real estate (7.2%, 95%CI 4.8-10.6), and highest among those who worked in the industry of Agriculture, forestry, animal husbandry and fishing (22.9%, 95%CI 15.5-32.4); the gender disparity was mainly found in those who worked in the industry of Agriculture, forestry, animal husbandry and fishing (AOR = 3.29, 95%CI 1.18-9.15), Manufacturing (AOR = 1.41, 95% CI 1.09-1.82), Wholesale and retail trade (AOR = 1.48, 95% CI 1.07-2.06), and Accommodation and food service (AOR = 1.91, 95% CI 1.15-3.18).

CONCLUSION

The prevalence of depression in China had a wide variation by classifications of the employer and industry. Gender disparities were identified among workers from Sole proprietorship, Private enterprise, and self-employed, or workers from the industry of Agriculture, forestry, animal husbandry and fishing, Manufacturing, Wholesale and retail trade, and Accommodation and food service.

Influenza Antiviral Use in Patients Hospitalized With Laboratory-Confirmed Influenza in the United States, FluSurv-NET, 2015-2019

From surveillance data of patients hospitalized with laboratory-confirmed influenza in the United States during the 2015-2016 through 2018-2019 seasons, initiation of antiviral treatment increased from 86% to 94%, with increases seen across all age groups. However, 62% started therapy ≥3 days after illness onset, driven by late presentation to care.

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.

COVID-19 Vaccination Rates and Factors Affecting Vaccine Hesitancy among Pregnant Women during the Pandemic Period in Turkey: A Single-Center Experience

The new coronavirus disease (COVID-19), which was detected in the Wuhan region of China in 2019 and spread rapidly all over the world, was declared a pandemic by the WHO in 2020. Since then, despite widespread recommendations to prevent the spread of the disease and provide treatment for sick people, 6,573,968 people died all over the world, 101,203 of which in Turkey. According to the international adult vaccination guidelines, pregnant women have been recommended to get vaccinated against the new coronavirus disease, as well as influenza and tetanus, during pregnancy. Before this study, not enough information was available about the vaccination awareness and vaccination hesitancy rates of pregnant women living in Turkey. For this reason, we believe that our study will contribute to filling this gap in the literature. The main objective of this study was to investigate the vaccination rates of pregnant women in a local hospital in Turkey and the reasons for vaccine hesitancy in this patient group. The minimum sample size of the study was found to be 241, with 80% power, 0.2 effect size, and 95% confidence interval, at p < 0.05 significance level. We included 247 consecutive pregnant women who applied to the Samsun Training and Research Hospital Gynecology and Obstetrics Outpatient Clinics between January 2022 and April 2022. The researchers prepared a questionnaire by taking into account the characteristics of the local community. A preliminary survey with these questions was also conducted before starting the main study. The mean age of the pregnant women participating in the study was 28.7 ± 5.3 years, and the mean gestational age was 28.2 ± 7.9 weeks. Among the participants, 26.3% were university graduates or had a higher degree, and 17% were actively working; in addition, 93 (37.7%) of the 247 pregnant women had received the COVID-19 vaccine, 203 (82.2%) had received at least one dose of the tetanus vaccine, and only 1 (0.4%) person had been administered the influenza vaccine during pregnancy. The most common reason for COVID-19 vaccine refusal and hesitancy was safety concerns, while the low rates of tetanus and influenza vaccination were due to a lack of knowledge. These results show that it is important to inform and educate the pregnant population on this subject to improve their vaccination behavior.

[Seasonal Influenza - Update on Epidemiology, Prevention and Therapy]

Infection control measures and travel restrictions implemented during the COVID-19 pandemic have limited the transmission of seasonal influenza viruses as well. It must be assumed that after these public health measures have largely been lifted, influenza activity will sharply increase in the coming influenza season. Anticipating the potentially high number of cases, the co-circulation of influenza viruses and SARS-CoV-2, efforts to increase vaccination rates against both infectious diseases must be given more attention.

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.

Outcomes in Pregnant Persons Immunized with a Cell-Based Quadrivalent Inactivated Influenza Vaccine: A Prospective Observational Cohort Study

Objective: To evaluate pregnancy and infant outcomes among persons immunized with a cell-based quadrivalent inactivated influenza vaccine (IIV4c) during routine pregnancy care. Design: Prospective observational cohort. Setting: US-based obstetrics/gynecology clinics. Population: Pregnant persons. This US-based, prospective observational cohort study evaluated the safety of quadrivalent inactivated influenza vaccine (IIV4c; Flucelvax® Quad) in pregnant persons immunized over 3 influenza seasons between 2017 and 2020. Pregnant persons were immunized with IIV4c as part of routine care, after which their health care provides HCPs with all observational data to a single coordinating center. Follow-up data were collected at the end of the second trimester and/or at the time of pregnancy outcome. A scientific advisory committee reviewed the data. Prevalence point estimates were reported with 95% confidence intervals (CIs). Pregnancy outcomes included: live birth, stillbirth, spontaneous abortion, elective termination, and maternal death. Infant outcomes included: preterm birth (<37 weeks gestational age), low birth weight (<2500 g), or major congenital malformations (MCMs). Of the 665 evaluable participants, 659 (99.1%) had a live birth. No stillbirths (0% [95% CI 0.0−0.6]), 4 spontaneous abortions (1.9% [0.5−4.8]), and 1 elective termination (0.5% [0.0−2.6]) were reported. Among 673 infants, 9.2% (upper 95% CI 11.5%) were born prematurely, 5.8% (upper 95% CI 7.6%) had low birth weight, and 1.9% (upper 95% CI 3.1%) were reported to have an MCM. No maternal deaths were reported. Of the 2 infants who died shortly after birth, one was adjudicated as not related to the vaccine; the other’s cause could not be determined due to maternal loss to follow-up. The prevalence of adverse pregnancy outcomes or preterm birth, low birth weight, or MCMs in newborns was similar in persons vaccinated with IIV4c compared to the rates observed in US surveillance systems. The safety profile of IIV4c in pregnant persons is consistent with previously studied influenza vaccines.

A Prospective Cohort Study on Pregnancy Outcomes of Persons Immunized with a Seasonal Quadrivalent Inactivated Influenza Vaccine during Pregnancy

This US-based, prospective observational cohort study evaluated the safety of a quadrivalent inactivated influenza vaccine (IIV4; Afluria Quadrivalent) in pregnant persons immunized over four influenza seasons between 2017 and 2021. Pregnancy outcomes included live birth, stillbirth, spontaneous abortion, and elective termination. Infant events of interest were major congenital malformations (MCMs), preterm birth (<37 weeks gestational age), and low birth weight (LBW). Data were descriptive; prevalence point estimates were reported with 95% confidence intervals (CI). A total of 483 pregnant persons were given IIV4 and evaluated; 477 (98.8%) reported a live birth, and there were 2 stillbirths, 4 spontaneous abortions, and no elective terminations or maternal deaths. The prevalence rates of infant events were as follows: preterm birth, 7.2% (upper 95% CI, 9.6%); LBW, 5.4% (upper 95% CI, 7.4%); and MCMs, 0.8% (upper 95% CI, 1.9%). Point estimates and upper 95% CIs of the observed prevalence rates were lower than or similar to background prevalence in the general US population. Our findings suggest no evidence of a safety concern with vaccinating this group at high risk of influenza complications and are consistent with published data from databases and surveillance systems that monitor the safety of influenza vaccines in pregnant persons.

Influenza

Annual seasonal influenza epidemics of variable severity caused by influenza A and B virus infections result in substantial disease burden worldwide. Seasonal influenza virus circulation declined markedly in 2020-21 after SARS-CoV-2 emerged but increased in 2021-22. Most people with influenza have abrupt onset of respiratory symptoms and myalgia with or without fever and recover within 1 week, but some can experience severe or fatal complications. Prevention is primarily by annual influenza vaccination, with efforts underway to develop new vaccines with improved effectiveness. Sporadic zoonotic infections with novel influenza A viruses of avian or swine origin continue to pose pandemic threats. In this Seminar, we discuss updates of key influenza issues for clinicians, in particular epidemiology, virology, and pathogenesis, diagnostic testing including multiplex assays that detect influenza viruses and SARS-CoV-2, complications, antiviral treatment, influenza vaccines, infection prevention, and non-pharmaceutical interventions, and highlight gaps in clinical management and priorities for clinical research.

Progress towards the Development of a Universal Influenza Vaccine

Influenza viruses are responsible for millions of cases globally and significantly threaten public health. Since pandemic and zoonotic influenza viruses have emerged in the last 20 years and some of the viruses have resulted in high mortality in humans, a universal influenza vaccine is needed to provide comprehensive protection against a wide range of influenza viruses. Current seasonal influenza vaccines provide strain-specific protection and are less effective against mismatched strains. The rapid antigenic drift and shift in influenza viruses resulted in time-consuming surveillance and uncertainty in the vaccine protection efficacy. Most recent universal influenza vaccine studies target the conserved antigen domains of the viral surface glycoproteins and internal proteins to provide broader protection. Following the development of advanced vaccine technologies, several innovative strategies and vaccine platforms are being explored to generate robust cross-protective immunity. This review provides the latest progress in the development of universal influenza vaccines.