Birth outcomes following immunization of pregnant women with pandemic H1N1 influenza vaccine 2009-2010

Immune checkpoints are suppressed during pregnancy following influenza A virus infection

Influenza A virus (IAV) infection is a major health risk during pregnancy. Although vaccination and antiviral agents are widely used and reduce IAV-induced symptoms, they are not sufficient to control IAV infections in pregnancy, especially during pandemics. Respiratory viruses like IAV exploit immune alterations that occur during pregnancy, including the upregulation of immune checkpoint proteins (ICPs) like programmed death ligand-1 (PDL1), programmed cell death receptor 1 (PD1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA4). We hypothesize that blocking expression of PDL1 on innate immune cells will improve maternal immunity following IAV infection. We used murine models of IAV infection during pregnancy with and without treatment with the immune checkpoint inhibitor (ICI), a-PDL1. Pregnant and nonpregnant mice were infected with mouse-adapted IAV (A/PR/8) and assessed at 3 days post infection (3 dpi). Lung cells were analyzed using flow cytometry. Lung mRNA expression of inflammatory and antiviral markers and histology was measured. Protein concentrations of inflammatory and antiviral markers, as well as viral titers were measured from lung bronchiolar lavage fluid (BALF). Lung function was also assessed. Following IAV infection, immune cells from pregnant mice had significant increases in the ICPs, PDL1, PD1, and CTLA4. a-PDL1 treatment effectively suppressed these ICPs and increased the activation marker, CD86. a-PDL1 treatment also reduced lung inflammatory cell infiltration and viral titers, increased antiviral responses, and improved lung function. Overall, IAV infection in pregnancy activates key inhibitory ICPs, leading to worsened disease outcomes. a-PDL1 treatment during IAV infection in pregnancy is an effective method to reduce ICP expression and improve overall immune cell responses.NEW & NOTEWORTHY Influenza infection worsens disease outcomes during pregnancy; however, treatment with anti-PDL1 can restore immune function during pregnancy.

Safety of the Seasonal Influenza Vaccine in 2 Successive Pregnancies

Importance

Although influenza vaccination has been found to be safe in pregnancy, few studies have assessed repeated influenza vaccination over successive pregnancies, including 2 vaccinations in a year, in terms of adverse perinatal outcomes.

Objective

To examine the association of seasonal influenza vaccination across successive pregnancies with adverse perinatal outcomes and whether the association varies by interpregnancy interval (IPI) and vaccine type (quadrivalent or trivalent).

Design, Setting, and Participants

This retrospective cohort study included individuals with at least 2 successive singleton live-birth pregnancies between January 1, 2004, and December 31, 2018. Data were collected from the Vaccine Safety Datalink, a collaboration between the Centers for Disease Control and Prevention and integrated health care organizations. Data analysis was performed between January 8, 2021, and July 17, 2024.

Exposures

Influenza vaccination was identified using vaccine administration codes. The vaccinated cohort consisted of people who received influenza vaccines during the influenza season (August 1 through April 30) in 2 successive pregnancies. The comparator cohort consisted of people identified as unvaccinated during both pregnancies.

Main Outcomes and Measures

Main outcomes were risk of preeclampsia or eclampsia, placental abruption, fever, preterm birth, preterm premature rupture of membranes, chorioamnionitis, and small for gestational age among individuals with and without vaccination in both pregnancies. Adjusted relative risks (RRs) from Poisson regression were used to assess the magnitude of associations. The associations with adverse outcomes by IPI and vaccine type were evaluated.

Results

Of 82 055 people with 2 singleton pregnancies between 2004 and 2018, 44 879 (54.7%) had influenza vaccination in successive pregnancies. Mean (SD) age at the start of the second pregnancy was 32.2 (4.6) years for vaccinated individuals and 31.2 (5.0) years for unvaccinated individuals. Compared with individuals not vaccinated in both pregnancies, vaccination in successive pregnancies was not associated with increased risk of preeclampsia or eclampsia (adjusted RR, 1.10; 95% CI, 0.99-1.21), placental abruption (adjusted RR, 1.01; 95% CI, 0.84-1.21), fever (adjusted RR, 0.87; 95% CI, 0.47-1.59), preterm birth (adjusted RR, 0.83; 95% CI, 0.78-0.89), preterm premature rupture of membranes (RR, 1.00; 95% CI, 0.94-1.06), chorioamnionitis (adjusted RR, 1.03; 95% CI, 0.90-1.18), or small for gestational age birth (adjusted RR, 0.99; 95% CI, 0.93-1.05). IPI and vaccine type did not modify the observed associations.

Conclusions and Relevance

In this large cohort study of successive pregnancies, influenza vaccination was not associated with increased risk of adverse perinatal outcomes, irrespective of IPI and vaccine type. Findings support recommendations to vaccinate pregnant people or those who might be pregnant during the influenza season.

Defining and reporting adverse events of special interest in comparative maternal vaccine studies: a systematic review

Introduction

The GAIA (Global Alignment on Immunisation Safety Assessment in Pregnancy) consortium was established in 2014 with the aim of creating a standardised, globally coordinated approach to monitoring the safety of vaccines administered in pregnancy. The consortium developed twenty-six standardised definitions for classifying obstetric and infant adverse events. This systematic review sought to evaluate the current state of adverse event reporting in maternal vaccine trials following the publication of the case definitions by GAIA, and the extent to which these case definitions have been adopted in maternal vaccine safety research.

Methods

A comprehensive search of published literature was undertaken to identify maternal vaccine research studies. PubMed, EMBASE, Web of Science, and Cochrane were searched using a combination of MeSH terms and keyword searches to identify observational or interventional studies that examined vaccine safety in pregnant women with a comparator group. A two-reviewer screening process was undertaken, and a narrative synthesis of the results presented.

Results

14,737 titles were identified from database searches, 435 titles were selected as potentially relevant, 256 were excluded, the remaining 116 papers were included. Influenza vaccine was the most studied (25.0%), followed by TDaP (20.7%) and SARS-CoV-2 (12.9%).Ninety-one studies (78.4%) were conducted in high-income settings. Forty-eight (41.4%) utilised electronic health-records. The majority focused on reporting adverse events of special interest (AESI) in pregnancy (65.0%) alone or in addition to reactogenicity (27.6%). The most frequently reported AESI were preterm birth, small for gestational age and hypertensive disorders. Fewer than 10 studies reported use of GAIA definitions. Gestational age assessment was poorly described; of 39 studies reporting stillbirths 30.8% provided no description of the gestational age threshold.

Conclusions

Low-income settings remain under-represented in comparative maternal vaccine safety research. There has been poor uptake of GAIA case definitions. A lack of harmonisation and standardisation persists limiting comparability of the generated safety data.

Pregnancy outcomes before and during COVID-19 pandemic in Tamale Metropolis, Ghana: A retrospective cohort study

BACKGROUND

The COVID-19 pandemic affected expectant mothers seeking maternal health services in most developing countries. Access and utilization of maternal health services including antenatal care (ANC) attendance and skilled delivery declined drastically resulting in adverse pregnancy outcomes. This study assessed pregnancy outcomes before and during COVID-19 pandemic in Tamale Metropolis, Ghana.

METHODS/DESIGN

A retrospective cohort study design was employed. A random sampling technique was used to select 450 women who delivered before or during the COVID-19 pandemic in Tamale Metropolis, Ghana. The respondents were interviewed using structured questionnaire at their homes. In this study, the data collected were socio-demographics characteristics, ANC attendance, before or during pandemic delivery, place of delivery and birth outcomes. Chi-square test and bivariate logistic regression analyses were performed under significant level of 0.05 to determine factors associated with the outcome variables.

RESULT

Of the 450 respondents, 51.8% were between 26 and 30 years of age. More than half (52.2%) of the respondents had no formal education and 93.3% were married. The majority (60.4%) of the respondents described their residence as urban setting. About 31.6% of the women delivered before the pandemic. The COVID-19 pandemic influenced place of delivery. The proportion of women who attended at least one ANC visit (84.5% before vs 70.5% during), and delivered at a hospital (76.8% before vs 72.4% during) were higher before the pandemic. More women were likely to deliver at home during COVID-19 (OR: 2.38, 95%CI: 1.52-3.74, p<0.001). Similarly, there was statistically significance difference between before and during COVID-19 delivery on at least one ANC attendance (OR: 2.72, 95%CI: 1.58-1.67, p<0.001). Women who delivered during COVID-19 were about twice more likely to develop complications (OR: 1.72, 95%CI: 1.03-2.87, p = 0.04).

CONCLUSION

ANC attendance and health facility delivery decreased while pregnancy complications increased during COVID-19. During disease outbreaks, outreach engagement strategies should be devised to increase access and utilization of maternal health services for marginalized and underserved populations. The capacity of health workers should be strengthened through skills training to manage adverse birth outcomes.

Anti-NMDA Receptor Encephalitis, Vaccination and Virus

Anti-N-methyl-d-aspartate (Anti-NMDA) receptor encephalitis is an acute autoimmune disorder. The symptoms range from psychiatric symptoms, movement disorders, cognitive impairment, and autonomic dysfunction. Previous studies revealed that vaccination might induce this disease. A few cases were reported to be related to H1N1 vaccine, tetanus/diphtheria/pertussis and polio vaccine, and Japanese encephalitis vaccine. Although vaccination is a useful strategy to prevent infectious diseases, in a low risk, it may trigger serious neurological symptoms. In addition to anti-NMDA receptor encephalitis, other neurological diseases were reported to be associated with a number of vaccines. In this paper, the anti-NMDA receptor encephalitis cases related to a number of vaccines and other neurological symptoms that might be induced by these vaccines were reviewed. In addition, anti-NMDA receptor encephalitis cases that were induced by virus infection were also reviewed.

The Importance of Vaccinating Children and Pregnant Women against Influenza Virus Infection

Influenza virus infection is responsible for significant morbidity and mortality in the pediatric and pregnant women populations, with deaths frequently caused by severe influenza-associated lower respiratory tract infection and acute respiratory distress syndrome (ARDS). An appropriate immune response requires controlling the viral infection through activation of antiviral defenses, which involves cells of the lung and immune system. High levels of viral infection or high levels of inflammation in the lower airways can contribute to ARDS. Pregnant women and young children, especially those born prematurely, may develop serious complications if infected with influenza virus. Vaccination against influenza will lead to lower infection rates and fewer complications, even if the vaccine is poorly matched to circulating viral strains, with maternal vaccination offering infants protection via antibody transmission through the placenta and breast milk. Despite the health benefits of the influenza vaccine, vaccination rates around the world remain well below targets. Trust in the use of vaccines among the public must be restored in order to increase vaccination rates and decrease the public health burden of influenza.