Maternal Vaccination Research Articles

Maternal Immunizations: Past, Present, and Future.

Maternal vaccines during pregnancy offer crucial protection against infections for both the pregnant person and their newborn. Vaccines against influenza, pertussis, coronavirus disease 2019, and respiratory syncytial virus are routinely recommended by the Centers for Disease Control and Prevention to safeguard pregnant women and their infants from potentially severe complications. Administering these vaccines during pregnancy helps transfer protective antibodies from the mother to the baby, enhancing immunity during the vulnerable early months of life. Extensive research supports the safety and efficacy of maternal vaccines, with numerous studies demonstrating their protective benefits for both pregnant people and newborns.

Awareness and Attitudes Among Parents of Females Aged 9-26 in Saudi Arabia Regarding Human Papillomavirus Vaccination.

Background Most cases of cervical cancer are caused by the human papillomavirus (HPV) infection, which can be prevented by vaccination. The HPV vaccine received approval in Saudi Arabia in 2010. Objectives This study aimed to examine the awareness and attitudes toward the HPV vaccine among parents of females aged 9-26 in Saudi Arabia and explore factors contributing to hesitancy or acceptance. Methods Conducted from November 2022 to June 2023 in Saudi Arabia, this cross-sectional study surveyed parents of females aged 9-26 using a self-administered questionnaire. Data collected included parental demographics, maternal vaccination status, awareness of the HPV vaccine, and attitudes toward it. Results Out of 551 participants, 445 (82.4%) were mothers. Most participants (331; 69.1%) had attained a university education, and approximately half (315; 57.2%) were employed. A total of 339 (61.5%) were aware of the HPV vaccine, 256 (46.5%) knew of its connection to cervical cancer, and 296 (53.7%) understood its preventive role. Among them, 230 participants demonstrated a good level of awareness, while 321 had a poor level. The majority (377; 68.4%) intended to vaccinate their daughters. Reasons for hesitancy among those unwilling included lack of awareness (234; 42.5%), insufficient information (206; 37.4%), fear of vaccines and needles (203; 36.8%), and conflicting medical opinions (165; 29.9%). Conclusion The current level of awareness regarding HPV vaccines within the general population is deemed satisfactory, with the majority expressing intent to vaccinate their daughters. Ongoing efforts are warranted to enhance awareness further, particularly by leveraging social media platforms and the expertise of trusted physicians and healthcare authorities. These endeavors are crucial for mitigating the preventable impact of HPV infection. Additionally, it is imperative to sustain immunization programs for HPV vaccines, ensuring streamlined vaccine administration.

EE217 Budget Impact of RSVpreF Maternal Vaccine Among Pregnant Women for Prevention of Respiratory Syncytial Virus Among Privately Insured Infants in Dubai, UAE

EE217 Budget Impact of RSVpreF Maternal Vaccine Among Pregnant Women for Prevention of Respiratory Syncytial Virus Among Privately Insured Infants in Dubai, UAE

Vaccines for Streptococcus agalactiae: current status and future perspectives.

A maternal vaccine to protect newborns against invasive Streptococcus agalactiae infection is a developing medical need. The vaccine should be offered during the third trimester of pregnancy and induce strong immune responses and placental transfer of protective antibodies. Polysaccharide vaccines against S. agalactiae conjugated to protein carriers are in advanced stages of development. Additionally, protein-based vaccines are also in development, showing great promise as they can provide protection regardless of serotype. Furthermore, safety concerns regarding a new vaccine are the main barriers identified. Here, we present vaccines in development and identified safety, cost, and efficacy concerns, especially in high-need, low-income countries.

Efficacy and safety of vaccines to prevent respiratory syncytial virus infection in infants and older adults: A systematic review and meta-analysis

ObjectivesTo determine the efficacy and safety of respiratory syncytial virus (RSV) vaccines in infants and older adults. MethodsWe performed a systematic review and meta-analysis of randomized control trials that evaluated the efficacy of maternal RSV immunization against infections in infants, as well as the efficacy of RSV vaccines in older adults. The primary outcome was the vaccine efficacy against RSV-related lower respiratory tract disease (LRTD). Grading of Recommendations Assessment, Development and Evaluation criteria was used to evaluate the level of evidence. ResultsTen trials were included in the review. For maternal vaccination, the RSV vaccine showed favourable efficacy against RSV-related LRTD (vaccine efficacy 57.3%, 95% confidence interval [CI] 31.3-73.5; low certainty) and RSV-related severe LRTD (vaccine efficacy 81.9%, 95% CI 56.8-92.4; moderate certainty) in infants within 90 days after birth. For older adults, Meta-analysis showed that RSV vaccines could also reduce the risk of RSV-related LRTD (vaccine efficacy 78.3%, 95% CI 65.6-86.3; moderate certainty) and RSV-related severe LRTD (vaccine efficacy 86.5%, 95% CI 68.3-94.3; moderate certainty). There was no significant difference in serious adverse events between RSV vaccines and placebo. ConclusionRSV vaccines have the potential to offer protection against RSV disease in both infants and older adults, without apparent safety concerns.

COVID-19 vaccine acceptance and associated factors among pregnant and lactating women attending maternity care clinics in refugee camps in Jordan.

Despite the advantages of vaccination in preventing maternal and fetal problems, there were many concerns in the medical community regarding vaccine safety for pregnant women, and this has put obstetricians in a challenging situation when it comes to advising their pregnant patients on whether to obtain the vaccine. This study was performed to define the level of acceptance of COVID-19 vaccination and assess the impact of COVID-19 attitudes and knowledge on vaccine acceptance between pregnant and lactating Syrian women who are seeking prenatal care services at the clinics in Azraq refugee camp in Jordan. A quantitative, cross-sectional study utilizing a non-probability convenience sample. A validated and reliable self-administered questionnaire consisting of four sections was used. A total of 412 pregnant/lactating women was recruited The acceptance rate of the COVID-19 vaccine among participants was 86.5%. There was a significant positive moderate association between respondents' attitudes and knowledge around the COVID-19 vaccine and their acceptance of the vaccine (r = .468, p < .001, r = .357, p < .001), respectively. To effectively mitigate the COVID-19 pandemic and achieve collective protection, decision-makers must intensify the efforts in promoting the importance of maternal vaccination, especially in vulnerable communities that suffer the most from pandemic outcomes.

A latent class analysis of factors influencing preferences for infant respiratory syncytial virus (RSV) preventives among pregnant people in the United States

ABSTRACT A maternal vaccine and long-acting monoclonal antibody (mAb) were recently approved to protect infants against respiratory syncytial virus (RSV). We identified subgroups of pregnant people with different preferences for RSV preventives and respondent characteristics associated with subgroup membership. An online survey, including a discrete choice experiment (DCE), was conducted among US pregnant people. RSV preventive attributes included effectiveness, duration of protection during RSV season, injection recipient/timing, preventive type (vaccine or mAb), and type of visit required to receive injection. In DCE choice tasks, pregnant people selected between two hypothetical preventive profiles with varying attribute-levels and a no-preventive option. Logistic regression, including latent class analysis (LCA), was used to analyze the data. Of 992 pregnant people (mean age: 30.0 years), 60.3% were expecting their second/later birth. LCA identified three preference subgroups: ‘Effectiveness’ (preventive choice mostly driven by increases in effectiveness; 51.4% class membership probability), ‘Season’ (preventive choice mostly driven by improvement in duration of protection during the RSV season; 39.2% class membership probability), and ‘No Preventive’ (frequently chose no-preventive option; 9.4% class membership probability). ‘Effectiveness’ and ‘Season’ preferred maternal vaccine over mAb; mAb was preferred by ‘No Preventive.’ Perceiving RSV as serious for infants, higher health literacy, and lower household income were associated with ‘Effectiveness.’ Perceiving RSV as serious for pregnant people was associated with ‘Season.’ Perceiving RSV to not be serious for pregnant people and not being employed were associated with ‘No Preventive.’ Subgroups of pregnant people vary in preferences for RSV preventives. Most pregnant people preferred a maternal vaccine, although some may be more willing to accept alternative preventive options.

COVID-19 vaccine and non-syndromic orofacial clefts in five arab countries. A case-control study.

Risk factors for non-syndromic orofacial cleft (NSOFCs) include genetic profile and environmental exposure to medication and illnesses during pregnancy. We assessed the association between the COVID-19 vaccination and the incidence of NSOFC across five Middle Eastern countries. This multi-country, hospital-based, case-control study included infants with NSOFCs whose first 3 intrauterine months coincided with the time when pregnant women were allowed to receive COVID-19 vaccination in the countries participating in the study. Newborns with NSOFCs were examined for cleft type and their parents were interviewed for maternal exposures and COVID-19 vaccination. Controls were newborns matched to cases in gender and setting. The study recruited 977 (348 children with NSOFCs and 629 controls). Maternal use of nicotine (Adjusted Odds Ratio (AOR): 2.437; P = 0.044) and family history of NSOFC (AOR: 11.059; P < 0.001) increased significantly the AOR of having a child with NSOFC. On the other hand, COVID-19 vaccine administration to pregnant mothers have significantly decreased the AOR of having a child with NSOFC (AOR: 0.337; P = 0.006). This study suggests that COVID-19 vaccination is not related to NSOFC and might protect against having a child affected with such a congenital anomaly. The finding of this study is important for healthcare providers for considering COVID-19 vaccination for pregnant woman. Clear communication and education about the potential risks and benefits would be crucial for informed decision-making. The study's results would directly impact pregnant individuals, as they would need accurate information to make informed decisions about their health and the health of their infants.

Cost-Effectiveness Analysis of Maternal Respiratory Syncytial Virus Vaccine in Protecting Infants from RSV Infection in Japan.

Respiratory syncytial virus (RSV) is one of the major causes of respiratory tract infections among children. Until recently, the monoclonal antibody palivizumab was the only RSV prophylaxis available in Japan. In 2024, the bivalent RSV prefusion F protein-based (RSVpreF) vaccine was approved for the prevention of RSV infection in infants by active immunization of pregnant women. In this study, we assessed the cost-effectiveness of a combined strategy of RSVpreF vaccine and palivizumab in Japanese setting. Using a Markov model, we evaluated prevented cases and deaths of medically attended RSV infections from birth to age 11months for each of the three healthcare settings: inpatient (hospitalization), emergency department visits, and outpatient visits. Incremental cost-effectiveness ratios (ICERs) were calculated from economic outcomes (intervention costs, medication costs, and productivity losses) and quality-adjusted life years (QALYs). Further, we calculated the maximum price of RSVpreF vaccine within which the program would be cost-effective. In comparison with the current prophylaxis (palivizumab alone), a combined prophylaxis of year-round RSVpreF vaccination of pregnant women and palivizumab prescription for premature infants born in < 32weeks gestational age (wGA) and all infants with high risk prevented 14,382 medically attended cases of RSV (hospitalization, 7490 cases; emergency department, 2239 cases; outpatient, 4653 cases) and 7 deaths, respectively. From a healthcare payer perspective, when the price of RSVpreF vaccine was equal to or less than ¥23,948 (US$182), a combination prophylaxis was cost-effective under the ICER threshold of ¥5million per QALY. The other combination prophylaxis of year-round RSVpreF vaccination and palivizumab prescription of premature born in < 32wGA regardless of risk in infants was a dominant strategy (more effective and less costly). A combined prophylaxis of year-round RSVpreF vaccine and palivizumab could be a cost-effective strategy to protect neonates throughout the infant stage (< 1years old) in Japan.

HIV-related immune activation attenuates polyfunctional IgG and memory B-cell responses to Tdap immunization during pregnancy

Maternal pertussis vaccination with Tdap vaccine is recommended to protect newborns from severe postnatal infection. HIV-exposed uninfected (HEU) infants have a higher incidence of pertussis infection and may particularly benefit from maternal immunization. The impact of HIV infection on the quality of IgG and memory B cell (MBC) responses to Tdap vaccination in pregnant women (PW) living with HIV (PWH) is unknown. In this observational study, humoral immune responses to Tdap vaccination, including IgG levels, Fc-dependent effector functions, and MBC frequencies, were measured before and after vaccination in 40 PWH and 42 HIV-uninfected PW. Placental transfer of IgG and avidity were assessed in cord blood (CB). Soluble and cellular immune activation markers were quantified at baseline. One month after vaccination, PWH had lower frequencies of MBC compared with HIV-uninfected PW. At delivery, PWH had attenuated pertussis-specific IgG levels and Fc-dependent effector functions. Reduced levels of maternal vaccine polyfunctional IgG and IgG avidity were transferred to HEU as compared to HIV-unexposed newborns. After adjustment with ethnicity, maternal antibody levels and gestational age at vaccination, HIV infection was independently associated with decreased levels of PT specific-IgG in CB. Both maternal and neonatal pertussis-specific IgG responses as well as PT-specific IgG avidity were inversely correlated with maternal sCD14 levels before vaccination among PWH. Maternal HIV infection is associated with attenuated humoral immune responses to Tdap vaccination that correlate with sCD14. Suboptimal transfer of maternal immunity may further increase the risk of severe pertussis infection in HEU infants. This work was supported by IRIS Fund managed by the Foundation Roi Baudouin [2017J1820690206902], Association Vésale pour la Recherche Médicale and the Medical Council of CHU Saint-Pierre and has been funded in part with Federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, US Department of Health and Human Services, under Award No. U19AI145825. N.D. is a clinical researcher and A.M. is Research Director at the Fonds de la Recherche Scientifique (F.R.S.-FNRS), Belgium. M.E.A. was partially supported by NIHNIAID1U19AI14825. This article is published with the support of the Fondation Universitaire of Belgium.

Opportunities and challenges to the development and deployment of vaccines for pregnant women in Germany

Maternal immunisation is a powerful tool to protect both pregnant women and their children. A new maternal RSV vaccine holds promise to protect newborns from RSV-associated illness in the first few months of life, but no official recommendation has been made in Germany. Since RSV causes a significant burden of paediatric hospital admissions, we consider it a pertinent opportunity to review barriers to maternal vaccination in Germany, which might also apply to other settings. Access to vaccination for pregnant women in Germany is shaped by an interplay of legal, regulatory, institutional, and sociocultural factors, with a less permissive clinical research environment, delays in recommendation and roll-out, and lower acceptance by healthcare professionals and the population. Actionable recommendations to improve availability and uptake include coordination with other national regulatory bodies to reduce delays, awareness and literacy campaigns for health professionals and the general public, and capacity building for vaccine clinical research.

Persistence and Efficacy of Maternal COVID-19 Vaccine-Induced Antibodies in Human Milk: A Comprehensive Meta-Analysis

Abstract Background: The ongoing global health challenge posed by the COVID-19 pandemic has necessitated a thorough examination of vaccine efficacy, particularly the transfer of vaccine-induced immunity to infants via human milk. This meta-analysis aims to explore the persistence and efficacy of COVID-19 vaccine-induced antibodies in human milk, offering insights into passive immunity transfer to breastfeeding infants. Methods: We conducted a systematic review and meta-analysis of peer-reviewed studies published from January 2021 to December 2023, extracted from databases such as PubMed, Scopus, and Web of Science. Our focus was on studies measuring SARS-CoV-2-specific antibodies (IgA and IgG) in human milk following maternal COVID-19 vaccination. Results: Fifteen studies involving 1,200 lactating mothers who received mRNA COVID-19 vaccines were included. The analysis highlighted a consistent presence of SARS-CoV-2-specific IgA and IgG antibodies in human milk, persisting for up to six months post-vaccination. Conclusion: The results highlight the noteworthy transmission of COVID-19 antibodies via human milk, suggesting an extended duration of possible protection for neonates against SARS-CoV-2 infection. This argues in favor of immunizing nursing mothers as a preemptive public health strategy to provide their children passive immunity.

Maternal and neonatal IgG against Klebsiella pneumoniae are associated with broad protection from neonatal sepsis: a case-control study of hospitalized neonates in Botswana.

Sepsis is the leading postnatal cause of neonatal mortality worldwide. Globally Klebsiella pneumoniae is the leading cause of sepsis in hospitalized neonates. This study reports development and evaluation of ELISA for anti-Klebsiella IgG using dried blood spot samples and evaluates the association of anti-Klebsiella IgG (anti-Kleb IgG) antibodies in maternal and neonatal samples and the risk of neonatal sepsis. Neonates and their mothers were enrolled at 0-96 hours of life in the neonatal unit of a tertiary referral hospital in Gaborone, Botswana and followed until death or discharge to assess for episodes of blood culture-confirmed neonatal sepsis. Neonates with sepsis had significantly lower levels of Kleb-IgG compared to neonates who did not develop sepsis (Mann-Whitney U, p=0.012). Similarly, samples from mothers of neonates who developed sepsis tended to have less Kleb-IgG compared to mothers of controls (p=0.06). The inverse correlation between Kleb-IgG levels and all-cause bacteremia suggests that maternal Kleb-IgG is broadly protective through cross-reactivity with common bacterial epitopes. These data support the continued use of immunoglobulin assays using DBS samples to explore the role of passive immunity on neonatal sepsis risk and reaffirm the critical need for research supporting the development of maternal vaccines for neonatal sepsis.

Using Surface Immunogenic Protein as a Carrier Protein to Elicit Protective Antibody to Multiple Serotypes for Candidate Group B Streptococcal Glycan Conjugate Vaccines.

Group B Streptococcus (GBS) is a life-threatening opportunistic pathogen, particularly in pregnant women, infants, and the elderly. Currently, maternal vaccination is considered the most viable long-term option for preventing GBS mother-to-infant infection, and two polysaccharide conjugate vaccines utilizing CRM197 as a carrier protein have undergone clinical phase II trials. Surface immunogenic protein (Sip), present in all identified serotypes of GBS strains so far, is a protective surface protein of GBS. In this study, the type Ia capsular polysaccharide (CPS) of GBS was utilized as a model to develop candidate antigens for a polysaccharide conjugate vaccine by coupling it with the Sip of GBS and the traditional carrier protein CRM197. Serum analysis from immunized New Zealand rabbits and CD1 mice revealed that there was no significant difference in antibody titers between the Ia-Sip group and Ia-CRM197 group; however, both were significantly higher than those observed in the Ia polysaccharide group. Opsonophagocytosis and passive immune protection results using rabbit serum indicated no significant difference between the Ia-Sip and Ia-CRM197 groups, both outperforming the Ia polysaccharide group. Furthermore, serum from the Ia-Sip group had a cross-protective effect on multiple types of GBS strains. The challenge test results in CD1 mice demonstrated that the Ia-Sip group provided complete protection against lethal doses of bacteria and also showed cross-protection against type III strain. Our study demonstrates for the first time that Ia-Sip is immunogenic and provides serotype-independent protection in glycan conjugate vaccines, which also indicates Sip may serve as an excellent carrier protein for GBS glycan conjugate vaccines and provide cross-protection against multiple GBS strains.

Modelling respiratory syncytial virus age-specific risk of hospitalisation in term and preterm infants

BackgroundRespiratory syncytial virus (RSV) is the most common cause of acute lower respiratory infections in children worldwide. The highest incidence of severe disease is in the first 6 months of life, with infants born preterm at greatest risk for severe RSV infections. The licensure of new RSV therapeutics (a long-acting monoclonal antibody and a maternal vaccine) in Europe, USA, UK and most recently in Australia, has driven the need for strategic decision making on the implementation of RSV immunisation programs. Data driven approaches, considering the local RSV epidemiology, are critical to advise on the optimal use of these therapeutics for effective RSV control.MethodsWe developed a dynamic compartmental model of RSV transmission fitted to individually-linked population-based laboratory, perinatal and hospitalisation data for 2000–2012 from metropolitan Western Australia (WA), stratified by age and prior exposure. We account for the differential risk of RSV-hospitalisation in full-term and preterm infants (defined as < 37 weeks gestation). We formulated a function relating age, RSV exposure history, and preterm status to the risk of RSV-hospitalisation given infection.ResultsThe age-to-risk function shows that risk of hospitalisation, given RSV infection, declines quickly in the first 12 months of life for all infants and is 2.6 times higher in preterm compared with term infants. The hospitalisation risk, given infection, declines to < 10% of the risk at birth by age 7 months for term infants and by 9 months for preterm infants.ConclusionsThe dynamic model, using the age-to-risk function, characterises RSV epidemiology for metropolitan WA and can now be extended to predict the impact of prevention measures. The stratification of the model by preterm status will enable the comparative assessment of potential strategies in the extended model that target this RSV risk group relative to all-population approaches. Furthermore, the age-to-risk function developed in this work has wider relevance to the epidemiological characterisation of RSV.

GBS vaccines in the UK: a round table discussion.

Group B streptococcus (GBS) remains a leading cause of infant sepsis, meningitis and death despite intrapartum antibiotic prophylaxis. A vaccine is urgently required, and two candidates are in advanced clinical trials. For successful GBS vaccine implementation, especially if a vaccine is licensed based on an immunological threshold, there must be cross-sector engagement, effective advocacy, robust plans for phase IV studies and equitable access. A round-table discussion, held at St George's University of London, reviewed the current position of GBS vaccines in the UK context, focusing on phase IV plans, convening a diverse group of stakeholders from across the UK, with a role in GBS vaccine licensure, advocacy, implementation or effectiveness evaluation.Presentations outlined the latest UK epidemiology, noting the rising infant invasive GBS (iGBS) infection rates from 1996 to 2021 for both early and late onset disease, with the highest disease rates in Black infants (1.1/1000 livebirths vs white infants (0.81/1000 livebirths). Potential coverage of the candidate vaccines was high (>95%). Regulatory input suggested that EU regulators would consider waiving the need for a pre-licensure efficacy study if a putative correlate of protection could be adequately justified. Phase IV study methodologies for a GBS vaccine were considered, largely based on previous UK maternal vaccine assessments, such as a nationwide cohort study design using a vaccine register and a maternal services dataset. Other strategies were also discussed such as a cluster or stepped-wedge randomised trial to evaluate implementation outcomes. Opportunities for advocacy, education and engagement with additional key partners were discussed and identified. With an approved GBS vaccine a near possibility, planning of phase IV studies and identification of critical barriers to implementation are urgently needed. Cross-sector engagement is essential and will facilitate a successful pathway.

Healthcare Providers' and Pregnant People's Preferences for a Preventive to Protect Infants from Serious Illness Due to Respiratory Syncytial Virus.

We assessed the impact of respiratory syncytial virus (RSV) preventive characteristics on the intentions of pregnant people and healthcare providers (HCPs) to protect infants with a maternal vaccine or monoclonal antibodies (mAbs). Pregnant people and HCPs who treated pregnant people and/or infants were recruited via convenience sample from a general research panel to complete a cross-sectional, web-based survey, including a discrete choice experiment (DCE) wherein respondents chose between hypothetical RSV preventive profiles varying on five attributes (effectiveness, preventive type [maternal vaccine vs. mAb], injection recipient/timing, type of medical visit required to receive the injection, and duration of protection during RSV season) and a no-preventive option. A best-worst scaling (BWS) exercise was included to explore the impact of additional attributes on preventive preferences. Data were collected between October and November 2022. Attribute-level preference weights and relative importance (RI) were estimated. Overall, 992 pregnant people and 310 HCPs participated. A preventive (vs. none) was chosen 89.2% (pregnant people) and 96.0% (HCPs) of the time (DCE). Effectiveness was most important to preventive choice for pregnant people (RI = 48.0%) and HCPs (RI = 41.7%); all else equal, pregnant people (RI = 5.5%) and HCPs (RI = 7.2%) preferred the maternal vaccine over mAbs, although preventive type had limited influence on choice. Longer protection, protection starting at birth or the beginning of RSV season, and use for both pre-term and full-term babies were ranked highest in importance (BWS). Pregnant people and HCPs strongly preferred a preventive to protect infants against RSV (vs. none), underscoring the need to incorporate RSV preventives into routine care.

Exploring the consent process among pregnant and breastfeeding women taking part in a maternal vaccine clinical trial in Kampala, Uganda: a qualitative study

BackgroundThe involvement of pregnant women in vaccine clinical trials presents unique challenges for the informed consent process. We explored the expectations and experiences of the pregnant women, spouses/partners, health workers and stakeholders of the consent process during a Group B Streptococcus maternal vaccine trial.MethodsWe interviewed 56 participants including pregnant women taking part in the trial, women not in the trial, health workers handling the trial procedures, spouses, and community stakeholders. We conducted 13 in-depth interviews and focus group discussions with 23 women in the trial, in-depth interviews with 5 spouses, and 5 women not in the trial, key informant interviews with 5 health workers and 5 other stakeholders were undertaken.ResultsDecision-making by a pregnant woman to join a trial was done in consultation with spouse, parents, siblings, or trusted health workers. Written study information was appreciated by all but they suggested the use of audio and visual presentation to enhance understanding. Women stressed the need to ensure that their male partners received study information before their pregnant partners joined a clinical trial. Confidentiality in research was emphasised differently by individual participants; while some emphasised it for self, others were keen to protect their family members from being exposed, for allowing them to be involved in research. However, others wanted their community participation to be acknowledged.ConclusionWe found that pregnant women make decisions to join a clinical trial after consulting with close family. Our findings suggest the need for an information strategy which informs not only the pregnant woman, but also her family about the research she is invited to engage in.

Effects of the timing of maternal SARS-CoV-2 infection and vaccination status on placental transfer of antibodies to neonates: A cross-sectional study

ObjectivesTo assess the effects of timing of maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and vaccination status on placental transfer of antibodies to neonates. MethodsIn this cross-sectional study, chemiluminescence was employed to measure SARS-CoV-2 IgG antibody titers in paired maternal-infant samples from women infected during pregnancy who were vaccinated or unvaccinated. Generalized linear regression assessed factors affecting antibody transfer in infected pregnant women and neonatal titers. ResultsThe group with ≥90 days between infection and delivery showed a higher antibody transfer rate than the <90 days group (β= 0.33, 95%CI: 0.01-0.65). Neonatal IgG titers correlated significantly with maternal titers and with maternal infections more than 90 days before delivery. Among infected pregnant women, those who had received 2 or 3 doses of vaccine before pregnancy had higher neonatal antibody titers than those who were not vaccinated (β = 57.70, 95%CI: 31.33-84.07). ConclusionNeonates born to pregnant women who were vaccinated before infection showed higher antibody titers than neonates of pregnant women who were not vaccinated before infection. The transfer rate is higher in pregnant women with ≥90 days from infection to delivery than in those with <90 days. These findings highlight the importance of timely maternal vaccination to optimize maternal and infant immunity.

Maternal immunization and vitamin A sufficiency impact sow primary adaptive immunity and passive protection to nursing piglets against porcine epidemic diarrhea virus infection.

Porcine epidemic diarrhea virus (PEDV) causes a highly contagious enteric disease with major economic losses to swine production worldwide. Due to the immaturity of the neonatal piglet immune system and given the high virulence of PEDV, improving passive lactogenic immunity is the best approach to protect suckling piglets against the lethal infection. We tested whether oral vitamin A (VA) supplementation and PEDV exposure of gestating and lactating VA-deficient (VAD) sows would enhance their primary immune responses and boost passive lactogenic protection against the PEDV challenge of their piglets. We demonstrated that PEDV inoculation of pregnant VAD sows in the third trimester provided higher levels of lactogenic protection of piglets as demonstrated by >87% survival rates of their litters compared with <10% in mock litters and that VA supplementation to VAD sows further improved the piglets' survival rates to >98%. We observed significantly elevated PEDV IgA and IgG antibody (Ab) titers and Ab-secreting cells (ASCs) in VA-sufficient (VAS)+PEDV and VAD+VA+PEDV sows, with the latter maintaining higher Ab titers in blood prior to parturition and in blood and milk throughout lactation. The litters of VAD+VA+PEDV sows also had the highest serum PEDV-neutralizing Ab titers at piglet post-challenge days (PCD) 0 and 7, coinciding with higher PEDV IgA ASCs and Ab titers in the blood and milk of their sows, suggesting an immunomodulatory role of VA in sows. Thus, sows that delivered sufficient lactogenic immunity to their piglets provided the highest passive protection against the PEDV challenge. Maternal immunization during pregnancy (± VA) and VA sufficiency enhanced the sow primary immune responses, expression of gut-mammary gland trafficking molecules, and passive protection of their offspring. Our findings are relevant to understanding the role of VA in the Ab responses to oral attenuated vaccines that are critical for successful maternal vaccination programs against enteric infections in infants and young animals.