Seroprevalence of Bordetella pertussis antibodies in mothers and their newborn infants

Global prevalence of infections in newborns with respiratory complications: systematic review and meta-analysis

Background and Objectives

Newborns as a vulnerable population are exposed to congenital and acquired infections during and after birth. There are several reports of the isolation and reporting of infectious agents (IAs) in early life of newborns with respiratory manifestations, and the present comprehensive study provides a snapshot of the current global situation of the prevalence of IAs in newborns with respiratory symptoms.

Materials and Methods

A systematic search was conducted in main databases, including PubMed, Scopus, Web of science, and Google scholar. The pooled prevalence of infectious agents (IAs) in newborns was estimated using comprehensive meta-analysis software based on random effects model.

Results

Out of 44 inclusive studies (50 datasets) for IAs in newborns, the pooled prevalence was estimated to be 12.2% (95% CI: 6.40-22.0%) and the highest and lowest prevalence of IAs was related to the Brazil (78.2%, 95% CI: 31.0-96.6%), and UK (0.01%, 95% CI 0.01-0.01%) respectively.

Conclusion

The high prevalence of IAs in newborns emphasizes considers the necessary measures to prevent respiratory infections.

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 Lao PDR: Seroprevalence and disease

OBJECTIVES

Pertussis is a debilitating vaccine-preventable infection. The aim of this study was to determine susceptibility and exposure to pertussis in Lao PDR in different age groups and subpopulations.

METHODS

A total 3072 serum samples were obtained from different cohorts: children with documented vaccination, pre-schoolers, schoolchildren, blood donors, healthcare workers (HCWs), and pregnant women and paired cord blood. Samples were tested for anti-pertussis toxin IgG antibodies. A history of Bordetella pertussis exposure was defined according to antibody titres. Four hundred and seventy-five throat swabs and nasopharyngeal aspirates were analysed by PCR for the presence of B. pertussis in symptomatic children at the Children's Hospital in Vientiane.

RESULTS

Overall pertussis seroprevalence was 57.5%. The prevalence of titres indicating acute infection or recent vaccination or infection/vaccination within the last 12 months ranged from 7.4% (100/1356) in adults to 21.4% (25/117) in pre-schoolers (age 1-5 years). B. pertussis was detected in 1.05% (5/475) of children with respiratory symptoms in Vientiane Capital.

CONCLUSIONS

It is suggested that routine childhood vaccination, in particular outreach, as well as vaccination of HCWs should be strengthened. A childhood booster and vaccination of pregnant mothers should be considered. There is also a need to improve reporting and to introduce pertussis testing in at least one central facility.

Seroprevalence of Bordetella pertussis antibodies and anti-pertussis antibody response after a single dose of reduced-antigen combined diphtheria, tetanus, and acellular pertussis vaccine (Tdap) in pregnant Thai women

BACKGROUND

Maternal immunization with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) has recently been implemented to prevent infant pertussis. Tdap is still not routinely recommended in Thailand, and there are limited data to support or challenge this strategy.

OBJECTIVES

The primary aim was to determine the seroprevalence of anti-pertussis toxin antibodies (anti-PT IgG) among pregnant Thai women. The secondary aims were to evaluate antibodies response after Tdap vaccination between seronegative and seropositive mothers and to compare the different antibody titers at delivery among seropositive mothers who received Tdap to those who received tetanus-diphtheria vaccine (Td).

METHODS

This randomized clinical trial was conducted during April 2018 to April 2019 at Siriraj Hospital, Bangkok, Thailand. A total of 129 pregnant women were included. Paired blood samples for anti-PT IgG levels were obtained during the first antenatal visit and at delivery. A baseline cut-off value of <5 IU/ml indicated seronegativity. There were 29 exclusions from the original 129 enrollment. All seronegative participants (n = 69) received Tdap, while the seropositive group were randomized 1:1 to receive either Tdap (n = 18) or Td (n = 13) during 27-36 weeks' gestation. The antibody levels from both sera were compared between groups.

RESULTS

The seroprevalence of maternal anti-PT IgG was 33.3% (43/129). There was no significant difference in the increment of antibody levels after Tdap vaccination between the seronegative and seropositive groups (30.2 vs. 42 IU/ml; p = 0.183). Among seropositive groups, all Tdap recipients had increased antibody titers at delivery, while all Td recipients showed waning of immunity throughout gestation. (42 IU/ml vs. -7.4 IU/ml; p < 0.001).

CONCLUSION

Most pregnant Thai women have seronegative against pertussis. Most seropositive mothers had initial low antibody titers and their immunity significantly decreased before delivery. Our findings highlight the need for universal pertussis immunization in pregnancy regardless of individual baseline immunity.

Safety and effectiveness of acellular pertussis vaccination during pregnancy: a systematic review

Background

Infants < 3 months of age are at highest risk for developing severe complications after pertussis. The majority of pregnant women has low concentrations of pertussis-specific antibodies and thus newborns are insufficiently protected by maternally transferred antibodies. Acellular pertussis vaccination during pregnancy was recently implemented in various countries. Here, we assessed the evidence for safety and effectiveness of pertussis vaccination during pregnancy.

Methods

We searched Medline, Embase, and ClinicalTrials.gov from January 1st 2010 to January 10th 2019. We assessed risk of bias (ROB) using the Cochrane ROB tool and ROBINS-I. We evaluated the quality of evidence using the GRADE approach.

Results

We identified 1273 articles and included 22 studies (14 for safety; 8 for effectiveness), comprising 1.4 million pregnant women in safety studies and 855,546 mother-infant-pairs in effectiveness studies. No significant differences between vaccinated and unvaccinated women and their infants were observed for safety outcomes with the exception of fever and chorioamnionitis. Compared to no vaccination, three studies showed a significantly increased relative risk for the presence of the ICD-9 code for chorioamnionitis in electronic patient data after pertussis vaccination. However, no study reported an increased risk for clinical sequelae of chorioamnionitis after vaccination during pregnancy, such as preterm birth or neonatal intensive care unit admission. Vaccine effectiveness against pertussis in infants of immunized mothers ranged from 69 to 91% for pertussis prevention, from 91 to 94% for prevention of hospitalization and was 95% for prevention of death due to pertussis. Risk of bias was serious to critical for safety outcomes and moderate to serious for effectiveness outcomes. GRADE evidence quality was moderate to very low, depending on outcome.

Conclusion

Although an increased risk for a diagnosis of fever and chorioamnionitis was detected in pregnant women after pertussis vaccination, there was no association with a higher frequency of clinically relevant sequelae. Vaccine effectiveness for prevention of infant pertussis, hospitalization and death is high. Pertussis vaccination during pregnancy has an overall positive benefit-risk ratio. In view of the overall quality of available evidence ongoing surveillance of chorioamnionitis and its potential sequelae is recommended when pertussis vaccination in pregnancy is implemented.

Trial registration

PROSPERO CRD42018087814, CRD42018090357.

Serosurveillance for vaccine-preventable diseases: A look inside the pertussis experience

INTRODUCTION

Serological surveillance (serosurveillance) provides the most direct measure of herd immunity of vaccine-preventable diseases. Little is known about the opportunities and challenges of serosurveillance experiences, particularly pertussis.

OBJECTIVE

To describe the process of serosurveillance for vaccine-preventable diseases with an emphasis on the experience of pertussis in the metropolitan area of Antioquia (Valle de Aburrá) in 2015 and 2016 and analyze the contributions and challenges for its sustainability.

MATERIALS AND METHODS

We described the planning and conduction of serosurveillance of pertussis antibodies of mothers and in the umbilical cord at the time of delivery in eight hospitals based on random sampling and their capacity to advance the serosurveillance periodically. We compared the contributions and the challenges of this experience with other probabilistic and non-probabilistic programs.

RESULTS

We achieved the participation of hospitals and mothers respecting the delivery care process. We established a serum bank following ethical and technical guidelines. This program based on the random selection of hospitals and mothers has enabled the estimation of antibodies prevalence in mothers and in the umbilical cord, which has been possible given the high coverage of hospital care during childbirth at a lower cost and fewer risks than a population-based survey in conflictive areas. The main challenges for the sustainability of this program are the creation of stable jobs and access to funding and legal and methodological long-term frameworks.

CONCLUSIONS

Hospital serosurveillance as described is an option to monitor the impact of vaccination on the population. Our experience could be reproduced in other regions under similar conditions if the above-mentioned challenges are solved.

Association Between Third-Trimester Tdap Immunization and Neonatal Pertussis Antibody Concentration

IMPORTANCE

Immunization with tetanus, diphtheria, and acellular pertussis (Tdap) vaccine is recommended in the United States during weeks 27 through 36 of pregnancy to prevent life-threatening infant pertussis. The optimal gestation for immunization to maximize concentrations of neonatal pertussis toxin antibodies is unknown.

OBJECTIVE

To determine pertussis toxin antibody concentrations in cord blood from neonates born to women immunized and unimmunized with Tdap vaccine in pregnancy and optimal gestational age for immunization to maximize concentrations of neonatal antibodies.

DESIGN, SETTING, AND PARTICIPANTS

Prospective, observational, cohort study of term neonates in Houston, Texas (December 2013-March 2014).

EXPOSURES

Tdap immunization during weeks 27 through 36 of pregnancy or no Tdap immunization.

MAIN OUTCOMES AND MEASURES

Primary outcome was geometric mean concentrations (GMCs) of pertussis toxin antibodies in cord blood of Tdap-exposed and Tdap-unexposed neonates and proportions of Tdap-exposed and Tdap-unexposed neonates with pertussis toxin antibody concentrations of 15 IU/mL or higher, 30 IU/mL or higher, and 40 IU/mL or higher, cutoffs representing quantifiable antibodies or levels that may be protective until the infant immunization series begins. Secondary outcome was the optimal gestation for immunization to achieve maximum pertussis toxin antibodies.

RESULTS

Six hundred twenty-six pregnancies (mean maternal age, 29.7 years; 41% white, 27% Hispanic, 26% black, 5% Asian, 1% other; mean gestation, 39.4 weeks) were included. Three hundred twelve women received Tdap vaccine at a mean gestation of 31.2 weeks (range, 27.3-36.4); 314 were unimmunized. GMC of neonatal cord pertussis toxin antibodies from the Tdap-exposed group was 47.3 IU/mL (95% CI, 42.1-53.2) compared with 12.9 IU/mL (95% CI, 11.7-14.3) in the Tdap-unexposed group, for a GMC ratio of 3.6 (95% CI, 3.1-4.2; P < .001). More Tdap-exposed than Tdap-unexposed neonates had pertussis toxin antibody concentrations of 15 IU/mL or higher (86% vs 37%; difference, 49% [95% CI, 42%-55%]), 30 IU/mL or higher (72% vs 17%; difference, 55% [95% CI, 49%-61%]), and 40 IU/mL or higher (59% vs 12%; difference, 47% [95% CI, 41%-54%]); P < .001 for each analysis. GMCs of pertussis toxin antibodies were highest when Tdap vaccine was administered during weeks 27 through 30 and declined thereafter, reaching a peak at week 30 (57.3 IU/mL [95% CI, 44.0-74.6]).

CONCLUSIONS AND RELEVANCE

Immunization with Tdap vaccine during the third trimester of pregnancy, compared with no immunization, was associated with higher neonatal concentrations of pertussis toxin antibodies. Immunization early in the third trimester was associated with the highest concentrations.

Third-Trimester Maternal Vaccination Against Pertussis and Pertussis Antibody Concentrations

OBJECTIVE

To compare pertussis antibody concentrations in maternal venous serum (at the time of delivery) and umbilical cord arterial serum among women vaccinated with the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine from either 27-30 6/7 weeks of gestation or from 31-35 6/7 weeks of gestation.

METHODS

We conducted a prospective cohort study of pregnant women divided into two groups based on when Tdap was administered: 27-30 6/7 weeks of gestation and 31-35 6/7 weeks of gestation. Paired maternal and umbilical cord samples were obtained at the time of delivery to determine immunoglobulin G (IgG) concentrations to pertussis toxin and pertactin.

RESULTS

Eighty-eight pregnant women were enrolled. Cord serum pertussis toxin IgG concentrations were approximately twice maternal serum pertussis toxin IgG concentrations (91.6 vs 48.6 enzyme-linked immunoassay [ELISA] units/mL, P<.01) and were significantly correlated (Pearson correlation coefficient=0.85, P<.01). There was no significant difference in maternal serum pertussis toxin IgG concentrations (48.6 vs 48.6 ELISA units/mL, P=.99), cord serum pertussis toxin IgG concentrations (92.1 vs 90.7 ELISA units/mL, P=.95), and cord serum pertactin IgG concentrations (798 vs 730 international units/mL, P=.73) between the two groups. Furthermore, there was no correlation between time from vaccination to delivery and these three parameters. Cord serum pertussis toxin IgG concentrations were greater than 10 ELISA units/mL (ie, in the protective range) in 87% and 97% of those vaccinated from 27-30 6/7 weeks of gestation and from 31-35 6/7 weeks of gestation, respectively (P=.13).

CONCLUSION

Maternal vaccination against pertussis between 27 and 36 weeks of gestation was associated with a high percentage of newborns with antibody concentrations conferring protection and did not vary by gestational age at vaccination.

Review of vaccination in pregnancy to prevent pertussis in early infancy

Maternal pertussis vaccination has been introduced in several countries to protect infants from birth until routine infant vaccination takes place. This review assesses existing evidence on the effectiveness and safety of immunization in pregnancy. The search was finalized in April 2017 and was based on searches using several databases. The selection criteria included any experimental or observational study reporting on the immunogenicity, effectiveness or safety of vaccination with a pertussis-containing vaccine in pregnant women and their infants. Following de-duplication and exclusions, we identified 8395 studies, which were reduced to 46 for inclusion. The overall risk of bias was low, with the exception of some early studies and pharmacovigilance safety data. The evidence demonstrates efficient transplacental transfer of maternal antibodies in infants whose mothers were vaccinated with Tdap or Tdap/IPV in pregnancy, with good evidence that this protects against disease in young infants. Safety studies covering more than 150 000 women vaccinated mostly in the late second or third trimesters are generally consistent and provide reassurance of no significant increased risk of recognized maternal conditions or of adverse events (including congenital anomalies) in infants born to vaccinated women. The clinical significance of reduced seroconversion to pertussis following routine immunization is not yet clear, but no increased risk of pertussis in infants whose mothers were vaccinated in pregnancy was found following primary immunizations in North American and English studies. Most post-booster studies suggest that any blunting effect is short-lived and that longer-term protection in infants from active immunization is not compromised.

A General Lack of IgG Against Pertussis Toxin in Chinese Pregnant Women and Newborns

BACKGROUND

To investigate the level of pertussis-related antibodies in pregnant women and newborns.

METHODS

A total of 286 serum samples from healthy pregnant women and 221 cord samples from newborns were collected in 2016 in Beijing. A routine blood sample from pregnant women was obtained at 35 weeks of gestational age, and cord samples were collected in 20 minutes after delivery. The values from cord samples were used as the infant values. Anti-pertussis toxin (PT) IgG concentration was measured by ELISA (Euroimmun, Lübeck, Germany) using purified PT as a coating antigen. Newborns with anti-PT IgG ≤40 IU/mL in cord samples were considered to be unprotected against pertussis. Anti-PT IgG ≥100 IU/mL was considered to be indicative of a recent pertussis infection in pregnant women.

RESULTS

The anti-PT IgG concentration below the lower limit of detection (<5 IU/mL) occurred in 74.1% (212/286) of pregnant women and 66.5% (147/221) of newborns. Even with detectable anti-PT antibodies, the majority of pregnant women (79.7%, 59/74) and newborns (73.0%, 54/74) had antibody level of 5 to <20 IU/mL, and 13.5% (10/74) of pregnant and 14.9% (11/74) of newborns had antibody level of 20 to <40 IU/mL. The 75% percentiles for anti-PT IgG of pregnant women and newborns were 5.08 and 6.98 IU/mL, respectively. The prevalence of unprotected newborns as defined by anti-PT IgG ≤40 IU/mL was 95.9% (202/211). The prevalence of recent pertussis infection in pregnant women as defined by anti-PT IgG ≥100 was 0.7% (2/286).

CONCLUSIONS

The pregnant women and newborns were generally lack of protective antibody and are vulnerable to pertussis in Beijing, China. Although acellular pertussis vaccine is administrated in infancy in China, a booster vaccination to pregnant women should be considered for protecting young infants who are too young to start pertussis vaccination.

Seroprevalence of Maternal and Cord Antibodies Specific for Diphtheria, Tetanus, Pertussis, Measles, Mumps and Rubella in Shunyi, Beijing

Maternal antibodies contribute to the protection of young infants from infectious diseases during the early life. However, vaccinations for women of child-bearing age are not routine in China. Therefore, we investigated the level of protective immunity against vaccine preventable diseases in pregnant women and newborns in China. A total of 194 paired maternal and cord blood samples were collected in Beijing from 2016 to 2017. Antibodies specific for the antigens covered by diphtheria-tetanus-pertussis (DTP) and measles-mumps-rubella (MMR) vaccine were determined by ELISA (Euroimmun, Lübeck, Germany). The cut off value of ≥0.1 IU/ml (anti-diphtheria), >0.1 IU/ml (anti-tetanus), >40 IU/ml (anti-pertussis toxin), ≥200 IU/l (anti-measles), ≥45 RU/ml (anti-mumps) and ≥10 IU/ml (anti-rubella) were used to assess the percentage of newborns with protective IgG concentrations, respectively. The results revealed that 61.3%, 73.2%, 97.4%, 30.4%, 65.5% and 17.0% of newborns had no protection against diphtheria, tetanus, pertussis, measles, mumps and rubella. Only 1.0% and 23.7% of newborns had protection against all three components of DTP or MMR, respectively. The finding suggested that most of newborns were susceptible to diphtheria, tetanus, pertussis and mumps, almost one-third of this population had no immune protection against measles, and about one-sixth of them were under threat of rubella infection. These data supported the immunization program for DTP and MMR vaccine in women at child-bearing age.

Antibodies to Bordetella pertussis antigens in maternal and cord blood pairs: a Thai cohort study

Background

Pertussis is a vaccine-preventable disease, yet an increasing incidence of pertussis occurs in many countries. Thailand has a long-standing pertussis vaccination policy, therefore most expectant mothers today had received vaccines as children. The resurgence of pertussis among Thai infants in recent years led us to examine the pre-existing antibodies to Bordetella pertussis antigens in a cohort of 90 pregnant women.

Methods

We evaluated the IgG to the Pertussis toxin (PT), filamentous hemagglutinin (FHA) and pertactin (PRN) in maternal and cord blood sera using commercial enzyme-linked immunosorbent assays (ELISA).

Results

When values of >10 IU/ml were accepted as potential protective concentrations, we found that the percentages of unprotected infants were 73.3%, 43.3% and 75.5% for anti-PT, anti-FHA and anti-PRN IgG, respectively.

Discussion

These results may explain the susceptibility for pertussis among newborn infants in Thailand and support the requirement for a pertussis booster vaccine during pregnancy, which may contribute to the passive seroprotection among newborns during the first months of life.

Immunization During Pregnancy: Impact on the Infant

Maternal immunization has undergone a paradigm shift in recent years, as women and healthcare providers accept and recognize the benefits of this strategy not only for the pregnant woman but also for the developing fetus and young infant. This article reviews the evidence for active immunization during pregnancy, with an emphasis on perinatal and infant outcomes. Current recommendations for immunization during pregnancy are presented, with particular focus on the routinely recommended vaccines during pregnancy: influenza and Tdap (tetanus, diphtheria, and pertussis). We discuss future research directions, maternal vaccines in development, and considerations for optimizing and advancing this underutilized strategy.

Pertussis vaccination in pregnancy

Pertussis has had a resurgence with the highest incidence and complication rates in young infants, and deaths occurring mainly at < age 3 months. Infants are infected by older individuals whose immunity has waned. Strategies such as targeted immunization of infant caregivers have had limited success. Pertussis vaccination in pregnancy may protect infants through passive and active transfer of maternal antibodies that protect the infant until the primary immunization series. Studies show vaccinating pregnant women with acellular pertussis vaccine is safe for mother and infant, immunogenic with efficient transfer of antibodies to infants, and effective in preventing pertussis in young infants. Vaccine uptake in pregnant women is sub-optimal, but provider recommendation is the most important factor in improving vaccination rates. Studies are ongoing to determine the best timing of vaccination to protect infants, and into other strategies. Vaccinating pregnant women offers hope to prevent pertussis-related morbidity and mortality in infants worldwide.

Immunization of pregnant women: Future of early infant protection

Children in early infancy do not mount effective antibody responses to many vaccines against commons infectious pathogens, which results in a window of increased susceptibility or severity infections. In addition, vaccine-preventable infections are among the leading causes of morbidity in pregnant women. Immunization during pregnancy can generate maternal immune protection as well as elicit the production and transfer of antibodies cross the placenta and via breastfeeding to provide early infant protection. Several successful vaccines are now recommended to all pregnant women worldwide. However, significant gaps exist in our understanding of the efficacy and safety of other vaccines and in women with conditions associated with increased susceptible to high-risk pregnancies. Public acceptance of maternal immunization remained to be improved. Broader success of maternal immunization will rely on the integration of advances in basic science in vaccine design and evaluation and carefully planned clinical trials that are inclusive to pregnant women.

Pertussis resurgence in a highly vaccinated population, Mazandaran, North of Iran 2008-2011: an epidemiological analysis

OBJECTIVE

To describe the epidemiological characteristics of pertussis cases reported to Mazandaran Center for Diseases Control and Prevention (P-CDC) during the years 2008-2011 in Mazandaran, North of Iran.

METHODS

The patients included were those who fulfilled the WHO definition for pertussis or those clinically diagnosed by physicians. The demographic features of cases, their vaccination status, the incidence rate per 100,000 population, the relative proportion of cases for each age group, and their relation to vaccination status of the patients were all determined.

RESULTS

During the study period, a total of 518 cases of pertussis were reported; of which 43 were confirmed. The highest incidence rate and the largest proportion were 135.5 cases/100,000 and 37.7 %, respectively, observed in infants <12 mo of age. Almost 35.7 % of the cases were under vaccinated, however 54.4 % of them were fully vaccinated.

CONCLUSIONS

Pertussis infection has re-emerged in Mazandaran. It has caused a significant health problem in the susceptible young infants, and also among completely vaccinated children. Implementing strategies to protect these vulnerable infants and studies to evaluate the immunogenicity and efficacy of pertussis vaccine in Iran is recommended. It was difficult to confirm pertussis in the majority of cases, therefore, providing and improving laboratory diagnostic methods seems to be an urgent requirement.

Prevalence of antibody to Bordetella pertussis in neonates and prevalence of recent pertussis infection in pregnant women in Catalonia (Spain) in 2003 and 2013

BACKGROUND

Infections because of Bordetella pertussis still occur in infants and adults in European countries, despite vaccination coverage against pertussis being high.

METHODS

IgG antibody titers to pertussis toxin (anti-PT) were assessed using an enzyme-linked immunosorbent assay test (Serion ELISA classic) in 353 cord blood samples from neonates of a representative sample of pregnant women obtained in Catalonia (Spain) in 2013. Neonates with anti-PT titers ≤ 40 international units (IU)/mL were considered to be unprotected against pertussis. IgG-PT titers >100 IU/mL in umbilical cord samples were considered to be indicative of a current or recent pertussis infection (12 months) in pregnant women. The age-standardized prevalence of recent pertussis infection obtained in this study was compared with the prevalence obtained in 2003.

RESULTS

The mean anti-PT titer in neonates was 10.8 IU/mL and 89.8% of neonates were unprotected against pertussis. The prevalence of unprotected neonates as defined by cord blood anti-PT ≤ 40 IU/mL was 90%. The prevalence of recent pertussis infection in pregnant women as defined by cord blood anti-PT >100 IU/mL was 2%. The diphtheria-tetanus-pertussis vaccination coverage during childhood in pregnant women was 75%. The age-standardized prevalence of recent pertussis infection in pregnant women observed in this study (2.2%) was slightly higher than the prevalence obtained in 2003 (1.5%), with an odds ratio = 1.45 (95% confidence intervals: 0.5-3.9), although differences were not statistically significant.

CONCLUSIONS

Most neonates are unprotected against pertussis and pertussis infections are frequent in pregnant women in Catalonia. Infants and pregnant women should be the priority population groups for pertussis prevention programs in Catalonia.

Safety and immunogenicity of tetanus diphtheria and acellular pertussis (Tdap) immunization during pregnancy in mothers and infants: a randomized clinical trial

IMPORTANCE

Maternal immunization with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine could prevent infant pertussis.

OBJECTIVE

To evaluate the safety and immunogenicity of Tdap immunization during pregnancy and its effect on infant responses to diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccine.

DESIGN, SETTING, AND PARTICIPANTS

Phase 1-2, randomized, double-blind, placebo-controlled, clinical trial conducted from 2008 to 2012. Forty-eight pregnant women aged 18 to 45 years received Tdap (n = 33) or placebo (n = 15) at 30 to 32 weeks' gestation, with crossover immunization postpartum.

INTERVENTIONS

Tdap vaccination at 30 to 32 weeks' gestation or postpartum.

MAIN OUTCOMES AND MEASURES

Primary outcomes were maternal and infant adverse events, pertussis illness, and infant growth and development until age 13 months. Secondary outcomes were antibody concentrations in pregnant women before and 4 weeks after Tdap immunization or placebo, at delivery and 2 months' postpartum, and in infants at birth, at 2 months, and after the third and fourth doses of DTaP.

RESULTS

No Tdap-associated serious adverse events occurred in women or infants. Injection site reactions after Tdap immunization were reported in 26 (78.8% [95% CI, 61.1%-91.0%]) and 12 (80% [95% CI, 51.9%-95.7%]) pregnant and postpartum women, respectively (P > .99). Systemic symptoms were reported in 12 (36.4% [ 95% CI, 20.4%-54.9%]) and 11 (73.3% [95% CI, 44.9%-92.2%]) pregnant and postpartum women, respectively (P = .03). Growth and development were similar in both infant groups. No cases of pertussis occurred. Significantly higher concentrations of pertussis antibodies were measured at delivery in women who received Tdap during pregnancy vs postpartum (eg, pertussis toxin antibodies: 51.0 EU/mL [95% CI, 37.1-70.1] and 9.1 EU/mL [95% CI, 4.6-17.8], respectively; P < .001) and in their infants at birth (68.8 EU/mL [95% CI, 52.1-90.8] and 14.0 EU/mL [95% CI, 7.3-26.9], respectively; P < .001) and at age 2 months (20.6 EU/mL [95% CI, 14.4-29.6] and 5.3 EU/mL [95% CI, 3.0-9.4], respectively; P < .001). Antibody responses in infants born to women receiving Tdap during pregnancy were not different following the fourth dose of DTaP.

CONCLUSIONS AND RELEVANCE

This preliminary assessment did not find an increased risk of adverse events among women who received Tdap vaccine during pregnancy or their infants. For secondary outcomes, maternal immunization with Tdap resulted in high concentrations of pertussis antibodies in infants during the first 2 months of life and did not substantially alter infant responses to DTaP. Further research is needed to provide definitive evidence of the safety and efficacy of Tdap immunization during pregnancy.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00707148.

Decline of IgG pertussis toxin measured in umbilical cord blood, and neonatal and early infant serum

Maternal pertussis-specific antibodies are passively acquired by infants during pregnancy. An IgG pertussis toxin (IgG-PT) concentration of >20 U/ml is considered to protect neonates against pertussis. To evaluate the IgG concentration at birth and during the first two months of life, we examined the IgG-PT concentration in the umbilical cord blood and three times during the neonatal and early infant period. IgG-PT was measured by validated IgG-specific enzyme-linked immunosorbent assays (ELISA) in umbilical cord blood and in Guthrie card blood samples of umbilical cord blood in 2,790 children, born between 1 August 2006 and 1 December 2008. These measurements were comparable. All children with concentrations of IgG-PT >30 U/ml were included. IgG-PT was also measured in Guthrie card blood samples, when the neonates or early infants were 5 days, 1 month and 2 months old. The mean concentrations of IgG-PT were calculated. The mean concentration of IgG-PT in umbilical cord blood was 60.1 U/ml (LN 4.1; 0.6 SD; n = 103). At the age of 5 days, 1 month and 2 months, the mean concentration of IgG-PT was 40.6 U/ml (LN 3.7; 0.5 SD; n = 103), 20.7 U/ml (LN 3.0; 0.7 SD; n = 62) and 16.7 U/ml (LN 2.8; 0.9 SD; n = 61), respectively. Four percent of the neonates had a concentration of IgG-PT >30 U/ml in umbilical cord blood, which declined to levels around the concentration needed for protection against pertussis (>20 U/ml) in the first two months of life. Hence, it is of great importance to further investigate the safety of maternal immunisation during pregnancy to prevent life-threatening pertussis in newborns.

Tetanus, diphtheria, acellular pertussis vaccine during pregnancy: pregnancy and infant health outcomes

OBJECTIVE

To assess pregnancy and birth outcomes in infants born to women who did or did not receive tetanus, diphtheria, acellular pertussis (Tdap) vaccine during pregnancy.

STUDY DESIGN

Retrospective cohort. Pregnant women 12-45 years of age who received Tdap at Intermountain Healthcare facilities and their infants were identified and compared with mother-infant pairs without documented Tdap from May 2005 through August 2009. Primary measures included pregnancy outcomes and infant health outcomes at birth through 12 months.

RESULTS

From 162,448 pregnancies we identified 138 women (0.08%) with documented Tdap administration during pregnancy (cases); 552 pregnant women without documented Tdap were randomly selected as controls. Of 138 immunized women, 63% received Tdap in the first trimester and 37% after. Tdap was given most commonly as wound prophylaxis. The incidence of spontaneous or elective abortion was no greater in Tdap cases than in controls. There were no significant differences in preterm delivery, gestational age, or birth weight between groups. One or more congenital anomaly was identified in 3.7% (95% CI 1.2%-8.5%) of case infants and 4.4% (95% CI 2.7%-6.5%) of control infants (P = .749). In infants born to women receiving Tdap during pregnancy, 3.6% (0.8%-10.2%) had International Classification of Diseases, Ninth Revision, Clinical Modification diagnoses consistent with complex chronic conditions within 12 months compared with 10.4% (95% CI 7.2%-14.4%) of infants of controls (P = .054).

CONCLUSIONS

Documented Tdap administration during pregnancy was uncommon and occurred most often in the first trimester as prophylaxis following trauma. No increase in adverse outcomes was identified in infants born to women receiving Tdap compared with infants of controls.

Seroprevalance of pertussis antibodies in maternal and cord blood of preterm and term infants

BACKGROUND

The resurgence of pertussis has resulted in an increased morbidity and mortality, especially among young infants. The aim of our study was to determine the antibody concentrations against pertussis antigens in cord and maternal blood in both preterm and term infant-mother pairs and to evaluate the efficacy of transplacental antibody transfer.

METHODS

Antibodies to pertussis toxin (PT) and filamentous hemagglutinin (FHA) in maternal and cord blood samples were measured by in-house enzyme linked immunosorbent assay (ELISA) in 100 preterm infant-mother and 100 term infant-mother pairs. Geometric mean concentrations (GMCs) of pertussis antibodies and cord:maternal GMC ratios were calculated.

RESULTS

Cord GMCs for anti-PT and anti-FHA in the preterm group were 13.15 and 14.55 ELISA U/ml (EU/ml), respectively. Cord GMCs for anti-PT and anti-FHA in the term group were 19.46 and 19.18 EU/ml, respectively. Cord anti-PT GMC was significanlty lower in the preterm group (p=0.037). There were no differences between the groups with regard to maternal anti-PT and anti-FHA GMC. Placental transfer ratios for anti-PT and anti-FHA in preterms were 68% and 72%, respectively. The same ratios in terms were 107% and 120%, respectively and were significantly higher than those of preterms (p<0.001). Placental transfer ratios were even lower in preterms <32 weeks when compared to preterms ≥32 weeks and terms. There was a strong correlation between maternal and cord anti-pertussis antibody levels both in preterm and term infants.

CONCLUSIONS

Anti-pertussis antibody levels were generally low in infant-mother pairs and would not be adequate to confer protection until the onset of primary immunization series. Transplacental anti-pertussis antibody transfers and antibody levels were lower in the cord blood of preterm infants, especially in those <32 weeks. These findings support the rationale for maternal immunization, which in combination with cocooning, could be a better option for preterm infants.

Seroprevalence and placental transmission of maternal antibodies specific for Neisseria meningitidis Serogroups A, C, Y and W135 and influence of maternal antibodies on the immune response to a primary course of MenACWY-CRM vaccine in the United Kingdom

BACKGROUND

Maternal antibodies give neonates some protection against bacterial infection. We measured antibodies against Neisseria meningitidis serogroups A, C, Y and W135 in mothers and their 2-month-old infants at study enrollment. We also assessed the impact of maternal antibody present at 2 months of age on the immune response to a primary course of quadrivalent meningococcal conjugate vaccine (MenACWY-CRM197) given at 2 and 4 months of age.

METHODS

This was a single-center, open-label, randomized study undertaken in Oxford, United Kingdom. Two hundred sixteen healthy infants were enrolled in the study and vaccinated with MenACWY-CRM197 at 2 and 4 months of age. Blood was obtained from all mothers, in a subset of infants at 2 months and all infants at 5 months. Antibody and memory B-cell responses at 5 months were correlated with maternal antibodies.

RESULTS

Mothers had low IgG antibodies against serogroups C, W135 and Y polysaccharides, but high serogroup A antibody, whereas 61-78% had protective human complement serum bactericidal activity (hSBA) (≥1:4) for serogroups C, W135 and Y but only 31% for serogroup A. Only 9%, 32%, 45% and 19% of 2-month-old infants had hSBA ≥1:4 for serogroups A, C, W135 and Y, respectively. Maternal antibody had little association on responses to MenACWY-CRM197, except a moderate negative association between MenC-specific bactericidal antibody at 2 and 5 months (r = -0.5, P = 0.006, n = 28) and between carrier-specific IgG antibody at 2 months and MenC-specific hSBA/IgG antibody at 5 months (r = -0.4, P = 0.02 and 0.04, n = 32 and 23). Nonetheless, 90% of infants achieved protective MenC-hSBA titers after vaccination at 2 and 4 months of age.

CONCLUSIONS

The levels of serogroup-specific meningococcal antibodies were low in mothers and 2-month-old infants. Immunizing mothers before or during pregnancy with meningococcal conjugate vaccines might increase antibody levels in early infancy and provide protection against infection due to N. meningitidis.

Importance of timing of maternal combined tetanus, diphtheria, and acellular pertussis (Tdap) immunization and protection of young infants

BACKGROUND

Pertussis booster vaccine (Tdap) recommendations assume that pertussis-specific antibodies in women immunized preconception, during, or after previous pregnancies persist at sufficient levels to protect newborn infants.

METHODS

Pertussis-specific immunoglobulin G (IgG) was measured by IgG-specific enzyme-linked immunosorbent assay (ELISA) in maternal-umbilical cord serum pairs where mothers received Tdap during the prior 2 years. Geometric mean concentrations (GMCs) of pertussis antibodies and cord-maternal GMC ratios were calculated.

RESULTS

One hundred five mothers (mean age, 25.3 years [range, 15.3-38.4 years]; mean gestation, 39 weeks [range, 37-43 weeks]) immunized with Tdap vaccine a mean of 13.7 months (range, 2.3-23.9 months) previously were included; 72 (69%) had received Tdap postpartum, 31 at a routine healthcare visit and 2 as contacts of another newborn. There was no difference in GMCs for pertussis-specific IgG in maternal delivery or infant cord sera for women immunized before (n = 86) or during (n = 19) early pregnancy. Placental transport of antibodies was 121%-186% from mothers immunized before and during pregnancy, respectively. Estimated GMC of IgG to pertussis toxin was <5 ELISA units (EU)/mL at infant age 2 months (start of infant immunization series). More infants of mothers immunized during pregnancy had pertussis toxin levels estimated to be higher than the lower limit of quantitation of the assay (4 EU/mL) through age 2 months (52% vs 38%; P = .34).

CONCLUSIONS

Infants of mothers immunized preconception or in early pregnancy have insufficient pertussis-specific antibodies to protect against infection. Maternal immunization during the third trimester, immunization of other infant contacts, and reimmunization during subsequent pregnancies may be necessary.

Vaccination during pregnancy

Pregnant women and their newborns are susceptible to infectious diseases. Healthcare providers must have the knowledge to provide advice and to support the use of immunizations for women who wish to ensure a healthy pregnancy. Several vaccines are now available for adolescents and women of childbearing age. Vaccination during pregnancy has the potential to provide protection to both mother and infant. Influenza and tetanus/diphtheria vaccines are routinely recommended for pregnant women. Other vaccines are available for women at risk for infection due to exposure, underlying medical conditions or travel. Live vaccines are contraindicated during pregnancy. Vaccines are underutilized in pregnancy due to safety, practical and liability barriers. To address physicians and patients' concerns, research is ongoing to further support vaccination during pregnancy as an efficient, safe and effective strategy with significant potential to improve the health of women and their infants worldwide.

Seroepidemiology of Bordetella pertussis infections in the twin cities of Pakistan

BACKGROUND

Bordetella pertussis is the cause of whooping cough occurring mainly in children. The prevalence of this disease has been reduced largely due to worldwide mass vaccination with DTP vaccine. However, the immunity produced by the vaccination wanes by the passage of time. Still this disease kills around 2-4 million children annually. Adults may be a source of infection for infants and children. Furthermore, Bordetella pertussis has also been found to be associated with cases of persistent cough in adults in many countries.

AIM

The aim of this study was to study the exposure of the adult population to the Bordetella pertussis by detecting IgG antibodies.

MATERIALS AND METHODS

We performed Seroepidemiology of Bordetella pertussis infections in multiethnic twin cities of Pakistan (Rawalpindi and Islamabad) using a commercially available ELISA kit to have a picture of epidemiology of Bordetella pertussis in Pakistan. We targeted adults of age between 18-45 years (mean age 29.64 years).

RESULTS

The results of our study show a high percentage of seropositivity to Bordetella pertussis (89 percent), which indicates higher exposure to this organism and risk of infection to infants, children, adolescents and adults.

CONCLUSION

A high percentage of seropositive individuals are alarming to health care professionals as well as policy makers. Bordetella pertussis infections may be associated with their atypical manifestation in Pakistan. Adult vaccination with DTP is recommended to reduce the risk of infection in infants and children through adult reservoirs.

Maternally derived antibodies against Bordetella pertussis antigens pertussis toxin and filamentous hemagglutinin in preterm and full term newborns

We measured IgG-anti-pertussis toxin and -IgG-anti-filamentous hemagglutinin antibody values in 43 full term and 34 preterm infants and 79 mothers. Antibody values were generally low and mean values were higher in full term than preterm infants. Transfer ratios increased with gestational age of the newborns. Based on these findings, maternal and neonatal immunization strategies should be considered to protect young infants from pertussis.

Prevalence of pertussis antibodies in umbilical cord blood samples in Catalonia, Spain

The objective of the study was to determine the prevalence of detectable antipertussis antibodies (anti-PT) and recent pertussis infection in a representative sample (n=508) of pregnant women in Catalonia (Spain). Antipertussis (PT) antibodies were determined in cord blood samples using an in-house enzyme-linked immunosorbent assay test. The prevalence of detectable anti-PT levels was 72.8% and the prevalence of recent pertussis infection in mothers (cord blood anti-PT level of > or = 195 EU/mL was 1.8%. The (P<0.05) and the prevalence of recent pertussis infection decreased with maternal age (P< 0.01). Results obtained in this study show that it might be necessary to develop a pertussis vaccination program using acellular pertussis vaccines aimed at pregnant women to reduce the risk of pertussis infection during pregnancy and in neonates.

Infectious diseases in pregnancy: issues of screening, prevention, and treatment

Infectious disease recommendations that play a part in care during birth, or among hospitalized antepartum women, are updated with new information as evidence becomes available. At the time of hospitalization during pregnancy, attention to testing and treatment can prevent the transmission of infections to the newborn, can improve the management of the mother's health, and is an increasingly important aspect of patient safety initiatives. Obstetric and perinatal nurses who are aware of current recommendations play a critical role in disease prevention. This article discusses issues that are relevant for maternal child healthcare practitioners. Examples are used to illustrate concerns of particular importance during pregnancy, such as antibiotic-resistant infections, vaccine-preventable illness, and testing for infectious diseases.

Pertussis hospitalizations among infants in the United States, 1993 to 2004

OBJECTIVE

We sought to describe the rates of pertussis hospitalization among infants by using databases that do not rely on passive reporting and compare with results obtained from the passive national surveillance system.

METHODS

The incidence of infant pertussis hospitalization in 1993 to 2004 was determined by using 2 national hospitalization discharge databases (Nationwide Inpatient Sample and Kids' Inpatient Database) and the National Notifiable Disease Surveillance System/Supplemental Pertussis Surveillance System. Rates were determined for separate age groups among infants < 1 year of age. Pertussis complications and procedures were examined by using the Kids' Inpatient Database.

RESULTS

In 1993 to 2004, the pertussis hospitalization rates for infants < or = 2 months of age were generally stable, by the discharge databases. The incidence of infant pertussis hospitalization obtained from the Nationwide Inpatient Sample and Kids' Inpatient Database was approximately 2 times greater than that obtained from the passive reporting system. Infants 1 to 2 months of age had the highest incidence (239 hospitalizations per 100,000 live births in the 2003 Kids' Inpatient Database). An annual average of 2678 hospitalizations occurred in 2000 and 2003; 86% occurred in infants < or = 3 months of age. Among those with ages provided, 95% of infants who required mechanical ventilation and all of those who died were < or = 3 months of age.

CONCLUSIONS

Pertussis hospitalization incidence rates among the youngest infants were generally stable in 1993 to 2004 and were highest for infants 1 to 2 months of age. The impact of the new adolescent and adult tetanus-diphtheria-acellular pertussis vaccines on infant pertussis should be monitored through such discharge databases. Additional vaccination strategies should be evaluated to protect infants as early in life as possible.

Humoral immunity 5 years after booster immunization with an adolescent and adult formulation combined tetanus, diphtheria, and 5-component acellular pertussis vaccine

Persistence of antibodies following a single dose of Tdap vaccine (tetanus, diphtheria, and five-component acellular pertussis vaccine for use in individuals past childhood) was evaluated in a follow-up of adolescents (N=324) and adults (N=644) who had received Tdap in earlier clinical trials. Outcome measures were seroprotection (tetanus and diphtheria) or seropositivity (pertussis) and geometric mean titers. Humoral immune responses to all antigens were robust 1 month after initial immunization; antibodies exceeded pre-immunization levels 1, 3, and 5 years later. These data will contribute to selecting the optimal interval for booster doses of Tdap.

Prospects for prevention of childhood infections by maternal immunization

PURPOSE OF REVIEW

To review the literature on using maternal immunization as a strategy to prevent infections in young infants aged below 6 months

RECENT FINDINGS

Maternal immunization continues to reduce the incidence of neonatal tetanus worldwide. Despite increased influenza-related morbidity and mortality in pregnant women and in infants aged less than 6 months, compliance with US recommendations for immunization against influenza in pregnancy is poor. Polysaccharide vaccines against Haemophilus influenzae type b, Streptococcus pneumoniae and Neisseria meningitidis are safe and immunogenic in pregnancy. Protein conjugate vaccines against these infections would be likely to induce higher maternal antibody levels and improve placental transport, thereby further reducing the maternal and infant disease burden. Further studies of acellular pertussis vaccines for use in adolescents and adults should evaluate if maternal immunization could prevent life-threatening pertussis in young infants. Maternal immunization against group B streptococcus is projected to be superior to screening and/or chemoprophylaxis strategies in decreasing infant disease.

SUMMARY

Maternal immunization, with the passage of protective antibody to infants, is a potential strategy to prevent infection in infants who have not completed their primary immunization series from both specific infections of infancy and vaccine-preventable illnesses. Further evaluation of this strategy is supported by medical literature, but liability and educational barriers exist.

Maternal immunity provides protection against pertussis in newborn piglets

Pertussis continues to be a significant cause of morbidity and mortality in infants and young children worldwide. Methods to control the disease are based on vaccination with either whole-cell or acellular vaccines or treatment with antibiotics. However, despite worldwide vaccination infants are still at the highest risk for the disease. Here we used our newly developed newborn-piglet model to investigate whether transfer of maternal immunity can protect newborn piglets against infection with Bordetella pertussis. Pregnant sows were vaccinated with heat-inactivated B. pertussis or treated with saline (controls). Newborn piglets were allowed to suckle colostrum and milk for 4 to 5 days before they were challenged with 5 x 10(9) CFU of bacteria intrapulmonarily. Elevated levels of B. pertussis-specific secretory immunoglobulin A (S-IgA) and IgG antibodies were found in the colostrum and serum of vaccinated sows but not in those of control sows. Subsequently, significant levels of specific IgG and S-IgA were detected in the serum and bronchoalveolar lavage fluid of piglets born to vaccinated sows. Following infection with 5 x 10(9) CFU of B. pertussis, clinical symptoms, pathological alterations, and bacterial shedding were significantly reduced in piglets that had received passively transferred immunity. Thus, our results demonstrate that maternal immunization might represent an alternative approach to provide protection against pertussis in young infants.