Neonatal Pertussis, an Under-Recognized Health Burden and Rationale for Maternal Immunization: A Systematic Review of South and South-East Asian Countries

High circulation of pertussis in infants and close contacts in Antananarivo, the capital of Madagascar in Africa, and Cambodia in Asia

BACKGROUND

Reliable data on whooping cough, a highly contagious disease sometimes fatal for infants, are largely lacking in low- and middle-income countries.

METHODS

We conducted a hospital-based prospective study (PS) on infants, and a household contact-case investigation (CCI) for positive cases throughout Cambodia and in the city of Antananarivo, Madagascar, between 2017 and 2019. The PS, in which Bordetella diagnostics (qPCR) were performed, included infants aged ≤6 months presenting with ≥5 days of cough associated with one pertussis-like symptom. CCI was performed using qPCR and serology regardless of clinical signs.

RESULTS

In this study, 207 and 173 participants from Cambodia and Antananarivo were respectively enrolled. Respectively 26.1% (54/207) and 22.0% (38/173) of the infants were infected in the cohorts from Cambodia and Antananarivo. Cough longer than 10 days appeared as a risk factor in both countries, as well as coughing spells, apnea and normal pulmonary auscultation, having a coughing contact in Cambodia. In Antananarivo, being clinically well between coughing spells appeared as a risk factor. Five infants, all positive, died during the study. In Cambodia and Antananarivo respectively, 50.9% (118/232) and 67.8% (82/121) of the contact cases were positive. Respectively 94.4% (51/54) and 90.3% (28/31) of the households had at least one positive contact case.

CONCLUSION

The data show that pertussis circulates at high levels among infants and in their households both in Cambodia and in Antananarivo. Given the vulnerability of youngest infants, who are too young to receive fully primary vaccination, they need to be protected through boosters breaking transmission chains. Molecular diagnosis, as well as trained medical human resources to detect the disease early, are absolutely key to protect populations.

Evaluation of anti-Pertussis antibody levels in Iranian infants and children: Is it time to include booster acellular Pertussis Vaccines in the immunization schedule?

INTRODUCTION

The prevalence of anti-pertussis antibodies among infants and children in Iran has not been thoroughly investigated. Given that recommendations for booster vaccines are based on national disease epidemiology, we aimed to evaluate the seroprevalence of pertussis antibodies among infants and children in an Iranian referral hospital.

MATERIALS AND METHODS

A total of 1012 infants and children were included in the study. Serum samples were stored at -20 °C until analysis. Demographic characteristics of patients, including age, sex, trivalent diphtheria, tetanus, and whole-cell pertussis (DTwP) vaccination status, and time since DTwP vaccination were collected. Anti-pertussis IgG antibodies were measured using a commercial ELISA kit.

RESULTS

In this cross-sectional study, the median age of the participants was 35 months (IQR:9-72 months). In infants ≤2 months, only 15 % had positive anti-pertussis antibodies. This increased to 28 % in the 3 to 4 months group and 55 % in the 5 to 6 months group. The highest positivity rates (63 % and 66 %) were seen in the 7 to 18 months and 19 to 36 months age groups, respectively. Positivity declined to 45 % in the 37 to 72 months group, and 47 % in those over 72 months. A significant relationship was found between the time elapsed since vaccination and anti-pertussis IgG levels (p = 0.005).

CONCLUSION

Our study highlights a concerning prevalence of low anti-pertussis, especially among infants aged ≤2 months, where the majority displayed negative results. This situation underscores the vulnerability of newborns to pertussis due to insufficient immunity and emphasizes the urgent need for effective maternal vaccination strategies. Additionally, we observed a decline in anti-pertussis IgG levels after 36 months, raising concerns about waning immunity in older children. Continued research is crucial to evaluate the long-term efficacy of booster vaccines and to develop optimal vaccination strategies to protect infants and children from pertussis.

Evaluation of Pertussis Disease in Young Infants in India: A Hospital-Based Multicentric Observational Study

OBJECTIVES

To evaluate the incidence of laboratory-confirmed pertussis (LCP) among infants hospitalized with acute respiratory infections (ARIs) and meeting the Centers for Disease Control and Prevention (CDC)-recommended clinical case definition.

METHODS

An investigator-initiated active surveillance for clinically suspected cases (CSCs) of pertussis screened infants aged ≤6 mo hospitalized with ARIs during January 2020-April 2022 at seven centers across India. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect Bordetella pertussis in nasopharyngeal swabs. Infants were classified as having 'LCP' or 'probable pertussis' (PP).

RESULTS

Among 1102 screened infants, 400 participants met the CDC-2020 clinical case definition for pertussis. Of these, 34/400 (8.5%) had LCP and 46/400 (11.5%) had PP. The proportion of participants with LCP and PP was similar among infants aged 0-3 and 4-6 mo [LCP: 0-3 mo, 21/248 (~9%); 4-6 mo, 13/152 (~9%); PP: 0-3 mo, 30/248 (~12%); 4-6 mo, 16/152 (~11%)]. Cough illness lasted ≥2 wk in 3/34 (~9%) and 34/46 (~74%) participants with LCP and PP, respectively. Notably, 80% CSCs had neither LCP nor PP, and a respiratory pathogen apart from B. pertussis was detected in ~32%. Ventilation was required in 12 participants with LCP/PP.

CONCLUSIONS

In this first study from India based on revised CDC guidelines, the incidence of LCP was 8.5%; cough illness was not a predominant feature. Infants below the age appropriate for vaccination are prone to pertussis-related hospital admissions, ICU care, and ventilation. Maternal immunization may be evaluated for neonatal protection, in addition to other strategies, to decrease disease burden in this highly vulnerable group.

CLINICAL TRIAL REGISTRATION NUMBER

CTRI/2019/12/022449.

Effective and safe transfer of maternal antibodies persisting two months postpartum following maternal immunization with different doses of recombinant pertussis-containing vaccines

INTRODUCTION

Recombinant acellular pertussis (ap) vaccines containing genetically inactivated pertussis toxin (PTgen) and filamentous hemagglutinin (FHA) with or without tetanus (TT) and diphtheria (DT) vaccines (Td) were found safe and immunogenic in non-pregnant and pregnant women. We report here maternal antibody transfer and safety data in mothers and neonates.

METHODS

This is the follow up of a phase 2 trial in 2019 among 400 pregnant women who randomly received one dose of recombinant pertussis-only vaccine containing 1 µg PTgen and 1 µg FHA (ap1gen), or Td combined with ap1gen (Tdap1gen), or with 2 µg PTgen and 5 µg FHA (Tdap2gen), or with 5 µg PTgen and 5 µg FHA (TdaP5gen, Boostagen®, BioNet, Thailand) or chemically-inactivated acellular pertussis comparator (Tdap8chem, Boostrix™, GSK, Belgium), either in the second or third trimester of gestation. IgG against PT, FHA, TT and DT were assessed by ELISA, PT-neutralizing antibodies (PTNA) by Chinese Hamster Ovary cell assay and safety outcomes at delivery in mothers and at birth.

RESULTS

Anti-PT and anti-FHA geometric mean concentration (GMC) ratio between infants at birth and mothers at delivery was above 1 in all groups. PT GMC in infants at birth were ≥30 IU/mL in all groups with the highest titers in infants found in TdaP5gen group at birth (118.8 [95% CI 93.9-150.4]). At 2 months, PT GMC ratio to Tdap8chem (98.75% CI) was significantly higher for TdaP5gen (2.6 [1.7-4.0]) and comparable for other recombinant vaccines. No difference in PTNA titers at birth was observed between all groups nor between time of vaccination. Adverse events were comparable in all vaccine groups.

CONCLUSIONS

BioNet licensed (TdaP5gen and Tdap2gen) and candidate vaccines (Tdap1gen and ap1gen) when given to pregnant women in the second or third trimester of gestation are safe and have induced passive pertussis immunity to infants.

Detection and Severity Identification of Neonatal Seizure Using Deep Convolutional Neural Networks from Multichannel EEG Signal

Introduction

One of the most frequent neurological conditions in newborns is neonatal seizures, which may indicate severe neurological dysfunction. These seizures may have very subtle or very modest clinical indications because patterns like oscillatory (spike) trains begin with relatively low amplitude and gradually increase over time. This becomes very challenging and erroneous if clinical observation is the primary basis for identifying newborn seizures. In this study, a diagnosis system using deep convolutional neural networks is proposed to determine and classify the severity level of neonatal seizures using multichannel neonatal EEG data.

Methods

Datasets from publicly accessible online sources were used to compile clinical multichannel EEG datasets. Various preprocessing steps were taken, including the conversion of 2D time series data to equivalent waveform pictures. The proposed models have undergone training, and evaluations of their performance were conducted.

Results

The proposed CNN was used to perform binary classification with an accuracy of 92.6%, F1-score of 92.7%, specificity of 92.8%, and precision of 92.6%. To detect newborn seizures, this model is utilized. Using the proposed CNN model, multiclassification was performed with accuracy rates of 88.6%, specificity rates of 92.18%, F1-score rates of 85.61%, and precision rates of 88.9%. The results demonstrated that the suggested strategy can assist medical professionals in making accurate diagnoses close to healthcare institutions.

Conclusion

The developed system was capable of detecting neonatal seizures and has the potential to be used as a decision-making tool in resource-limited areas with a scarcity of expert neurologists.

Pertussis in India: Past, Present, and Future

While vaccines have markedly reduced the incidence of pertussis, a resurgence has occurred in many countries. Until recently, pertussis has not been recognized as an important public health challenge in India due to its successful infant immunization program. However, India still accounts for a large proportion of the world's cases, and increasing reports of pertussis in other countries and in neonates have regenerated interest in pertussis among Indian authorities. The Global Pertussis Initiative (GPI) Annual Meeting was held virtually in October 2020, in part, to gain a better understanding of the epidemiology and disease burden of pertussis and to explore opportunities to improve its prevention in India. There was a consensus that pertussis cases are being underestimated in India due to multiple factors, such as a reliance on passive surveillance and diagnostic challenges. India offers both whole-cell pertussis and acellular pertussis vaccines, but vaccine coverage is inconsistent across regions due to differences in vaccine availability, access to health care, and regional administrative challenges. This report summarizes the outcomes and considers the key clinical implications of this meeting. The GPI agreed that active surveillance of pertussis in India would be optimal and recommended several studies, including serosurveillance among women of reproductive age to assess the prevalence of recent pertussis infection and to enable policy changes that will enhance the rational use of acellular and whole-cell vaccines. It also recommended engagement with nongovernmental organizations in order to encourage pregnancy immunization in the public sector. To achieve effective control of pertussis in the future, the GPI recognizes there are opportunities to characterize the burden of pertussis in India appropriately and increase vaccination coverage in multiple age groups.

The perinatal health challenges of emerging and re-emerging infectious diseases: A narrative review

The world has seen numerous infectious disease outbreaks in the past decade. In many cases these outbreaks have had considerable perinatal health consequences including increased risk of preterm delivery (e.g., influenza, measles, and COVID-19), and the delivery of low birth weight or small for gestational age babies (e.g., influenza, COVID-19). Furthermore, severe perinatal outcomes including perinatal and infant death are a known consequence of multiple infectious diseases (e.g., Ebola virus disease, Zika virus disease, pertussis, and measles). In addition to vaccination during pregnancy (where possible), pregnant women, are provided some level of protection from the adverse effects of infection through community-level application of evidence-based transmission-control methods. This review demonstrates that it takes almost 2 years for the perinatal impacts of an infectious disease outbreak to be reported. However, many infectious disease outbreaks between 2010 and 2020 have no associated pregnancy data reported in the scientific literature, or pregnancy data is reported in the form of case-studies only. This lack of systematic data collection and reporting has a negative impact on our understanding of these diseases and the implications they may have for pregnant women and their unborn infants. Monitoring perinatal health is an essential aspect of national and global healthcare strategies as perinatal life has a critical impact on early life mortality as well as possible effects on later life health. The unpredictable nature of emerging infections and the potential for adverse perinatal outcomes necessitate that we thoroughly assess pregnancy and perinatal health implications of disease outbreaks and their public health interventions in tandem with outbreak response efforts. Disease surveillance programs should incorporate perinatal health monitoring and health systems around the world should endeavor to continuously collect perinatal health data in order to quickly update pregnancy care protocols as needed.

Pertussis in Asia: Recent country-specific data and recommendations

The Global Pertussis Initiative (GPI) Roundtable Meeting held in 2019, which preceded the COVID-19 pandemic, focused on the incidence, surveillance, and immunization practices for pertussis in the Asian region. Participants from China, India, Indonesia, Malaysia, Pakistan, Philippines, South Korea, Taiwan, and Thailand presented country-specific information on pertussis prevalence, diagnosis, surveillance, vaccine administration and schedules, maternal and neonatal disease rates, and policies and practice of vaccination during pregnancy. In recent years, many Asian countries have seen an increase in pertussis cases, although underreporting of the disease is a concern. Currently, most Asian countries have only passive surveillance for pertussis in place. There is a need for improved surveillance to determine the disease burden and justify vaccination policies and recommendations, such as essential vaccination, boosters, and vaccination during pregnancy. Better awareness of the disease in adolescents and adults is necessary, and infant and childhood vaccination schedules need to be improved in many countries. Differences between private versus public sector vaccination schedules and between whole-cell and acellular pertussis vaccines should continue to be examined. It can be anticipated that unmet needs in the prevention and management of pertussis will continue as the COVID-19 pandemic evolves and that key recommendations highlighted in this meeting report will be of ongoing importance.

Maternal immunization: trends in South and Southeast Asian countries

Maternal immunization has the potential to reduce neonatal deaths caused by vaccine-preventable infectious diseases. Elimination of maternal and neonatal tetanus from many countries illustrates the potential benefits of maternal immunization as a strategy to decrease neonatal mortality caused by vaccine-preventable infections. Many countries in South and Southeast Asia have high cases of neonatal deaths, which were historically attributed to vaccine-preventable infections. Still, these countries vary in recommendations regarding immunization of pregnant women. We reviewed the current recommendations for the use of tetanus toxoid, tetanus-diphtheria, or tetanus-diphtheria-acellular pertussis (Tdap) vaccines for immunization of pregnant women. In addition to protection against tetanus and diphtheria, administration of the Tdap vaccine to pregnant women could help protect neonates against pertussis until they can receive the first two vaccine doses of their primary course. Vaccination against seasonal influenza is also recommended in many countries worldwide for pregnant women as influenza can pose health risks for the mother-fetus unit and the infant. Despite the recognized benefit of influenza vaccination for pregnant women, only some South and Southeast Asian countries have implemented its recommendation. The success of maternal tetanus vaccination has kindled the interest in vaccines that can be safely administered during pregnancy. Future availability of vaccines against respiratory syncytial virus and group B streptococcus, for use in pregnant women, could help prevent neonatal infections, especially in regions where diseases are less controlled. Communicating the body of evidence that supports maternal immunization to obstetricians is key for achieving optimal vaccination coverage to ensure protection of neonates. The current review aims to create awareness about the existing and potential benefits of maternal immunization in South and Southeast Asia.

Vaccination in preterm and low birth weight infants in India

In India, the high neonatal and infant mortality rate is due in part to an increasing number of preterm and low birth weight (LBW) infants. Given the immaturity of immune system, these infants are at an increased risk of hospitalization and mortality from vaccine-preventable diseases (VPDs). In this narrative review, we screened the scientific literature for data on the risk of VPDs, vaccination delay and factors related to it in Indian preterm and LBW infants. Although routine childhood vaccinations are recommended regardless of gestational age or birth weight, vaccination is often delayed. It exposes these infants to a higher risk of infections, their associated complications, and death. After-birth complications, lack of awareness of recommendations, vaccine efficacy and effectiveness and concerns related to safety are some of the common barriers to vaccination. Awareness campaigns might help substantiate the need for (and value of) vaccination in preterm and LBW infants.

What is the context?

In India, the high neonatal mortality rate is due in part to an increasing number of pretern and low birth weight intants.

Affected infants have a poorly developed inmune system and are more susceptible to contracting vaccine-preventable diseases.

The Indian Academy of Pediatrics recommends vaccination according to the same schedule used for full term infants, following chronological (not gestational) age.

Delays in vaccinations increase the risk of preventable infections.

What is new?

Our review of the scientific literature shows that, in India:

infections have more serious conseuences in preterm and low birth weight infants

delays to vaccinate affected infants are common, mostly due to safety and effectiveness concerns from parents and healthcare pracitionrs.

What is the impact?

Improving mternal nutritional status and immunization, and perinatal care could help reduce the number of preterm and low birth weight infants.

Combining maternal immunization with vaccination of affected infants can confer safe and effective protection.

Awareness campaigns for parents and healthcare practitioners could address the issue of vaccination delay in pretern and low birth weight infants in India.

Etiologies of Hospitalized Acute Bronchiolitis in Children 2 Years of Age and Younger: A 3 Years' Study During a Pertussis Epidemic

Objective: In recent years, the incidence of Bordetella pertussis infection in infants and young children has been increasing. Multiple studies have suggested that B. pertussis may be one of the pathogens of bronchiolitis in infants and young children. However, the prevalence and clinic characteristic of B. pertussis in bronchiolitis is controversial. This prospective descriptive study evaluated the prevalence and clinical manifestations of infants and young children hospitalized for bronchiolitis with B. pertussis. Methods: Children hospitalized with bronchiolitis were eligible for a prospective study for 36 months from January 1, 2017, to December 31, 2019. Besides B. pertussis, 10 common respiratory viruses and Mycoplasma pneumoniae (MP) were confirmed by laboratory tests. Medical records of patients were reviewed for demographic, clinical characteristics, and laboratory examination. Results: A total of 1,092 patients with bronchiolitis were admitted. B. pertussis was detected in 78/1,092 (7.1%) patients. Of the 78 patients with B. pertussis bronchiolitis, coinfections occurred in 45 (57.7%) patients, most frequently with human rhinovirus (28/78, 35.9%), followed by MP (9/78, 11.4%), and human bocavirus (6/78, 7.7%). The peak incidence of B. pertussis infection was in May. A high leukocyte count could help distinguish B. pertussis-associated acute bronchiolitis from other acute bronchiolitis etiologies. After excluding coinfections, children with B. pertussis-only bronchiolitis exhibited a milder clinical presentation than those with RSV-only infection; also, children with MP-only and other pathogen infections revealed similar severity. The morbidity of B. pertussis was common (31/78, 39.7%) in infants with bronchiolitis under 3 months. Conclusion: In summary, B. pertussis is one of the pathogens in children with bronchiolitis, and coinfection of B. pertussis with other viruses is common in bronchiolitis. B. pertussis should be considered when patients hospitalized with bronchiolitis present a longer course and have an elevated leukocyte count. Patients with B. pertussis-associated bronchiolitis present a milder clinical presentation.

Lurking Infantile Pertussis: Experience from a Tertiary Care Center in Northern India

Objectives The aim is to study the clinical laboratory profile and outcome of infants with laboratory confirmed pertussis.

Methods In this retrospective study, records of 30 infants with laboratory confirmed pertussis, admitted to the pediatric department of a tertiary care hospital, were reviewed. Clinical features, laboratory parameters, and outcomes were noted.

Results Median (interquartile range age was 10 (7–24.5) weeks, with a male preponderance. Large majority (60%) of enrolled infants were less than 16 weeks of age and nine (30%) developed pertussis even before 8 weeks of age. Cough was universal (100%), followed by rapid breathing (73%), fever (70%), and apnea (10%). Bubble continuous positive airway pressure (CPAP), nasal prongs oxygen, and invasive ventilation were required in 15 (54%), 11 (39%), and 2 (7%) infants, respectively; 12 (40%) needed to be admitted to the pediatric intensive care unit. Anemia was observed in 28 (93%) and leukemoid reaction in 15 (50%). All except one were discharged successfully. None of the mothers had received tetanus, diphtheria, and pertussis or Tdap vaccination during pregnancy.

Conclusion Our study reports the continued occurrence of infantile pertussis in the community, suggesting reconsideration of our vaccination policy, including maternal immunization.

Use of a Neonatal-Mouse Model to Characterize Vaccines and Strategies for Overcoming the High Susceptibility and Severity of Pertussis in Early Life

Newborns and unvaccinated infants, compared to other age groups, are more susceptible to pertussis infection, manifesting severe symptoms leading to a higher mortality. The recent increase in pertussis cases demands more effective strategies to overcome this major health problem. In parallel with maternal-immunization, neonatal-immunization (NI) is a strategy needing revision. Here, using the intranasal-challenge-mouse-model we evaluated the protective capacity of NI in both naïve-mice and those with maternally acquired immunity. We tested our acellular-vaccine-candidate based on outer-membrane-vesicles derived from Bordetella pertussis (OMVP) that induces Th2-profile but also the recommended Th-profile for protection: Th1/Th17-profile and CD4 T-memory-cells that reside in the lungs. Commercial acellular-vaccine (aP) and whole cell-vaccine (wP) inducing mainly Th2-profile and Th1-profile, respectively, were also tested. Analyzing the induced immunity and protection capability of NI included in 1- or 2-dose schedules with the same or different types of vaccine, we detected that the aP-vaccine administered in either single- or 2-dose schedules protected against sublethal B. pertussis infection. Schedules consisting of doses of aP neonatally and of OMVP or wP vaccine during infancy greatly reduced bacterial lung colonization while inducing the highest levels of high-avidity anti-pertussis toxin (PTx) IgG. That OMVP or wP neonatal dose did not interfere with the protection of transferred maternal immunity was especially encouraging. Moreover, OMVP- or wP used as a neonatal dose enhanced the quality of the humoral immune response in immunized pups. Antibodies generated by OMVP-or wP-vaccinated mice born to aP-immunized mothers were of higher avidity than those from mice that harbored only maternal immunity; but when mothers and neonates were immunized with the same aP-vaccine, the humoral response in the neonates was partially suppressed through the blunting of the level of anti-PTx IgG induced by the neonatal aP dose. These results demonstrated that neonatal immunization is a possible strategy to be considered to improve the current pertussis epidemiology. For neonates without maternal-immunity, mixed-vaccination schedules that include the aP- and OMVP-vaccines appear to be the most appropriate to induce protection in the pups. For offspring from immune mothers, to avoid blunting-effect, NI should be carried out with vaccines other than those applied during pregnancy.