Pertussis immunisation during pregnancy: Antibody levels and the impact of booster vaccine

Pertussis (whooping cough) is a highly infectious disease caused by Bordetella pertussis. Mothers lacking adequate immunity and contracting the disease represent the biggest risk of transmission to new-borns, for which the disease is often a threat. The aim of the study was to estimate the frequency of pertussis susceptibility among pregnant women, in order to point out the need for a vaccine recall during pregnancy, and to evaluate the antibody response in already vaccinated women. A cross-sectional observational study was conducted in the blood test centre of “St. Anna” Obstetrics and Gynaecology Hospital in Turin (Piedmont, Italy). Eligibility criteria included pregnant women coming to the centre for any blood test, aged 18 or above and with gestational age between 33 and 37 weeks at the moment of the blood draw. The data collection was carried out from May 2019 to January 2020 and the concentration of anti-Pertussis Toxin (anti-PT) IgG was measured through the Enzyme-Linked Immunosorbent Assay (ELISA) technique. Two-hundred women (median age 35) were enrolled: 132 (66%) had received at least one dose of pertussis vaccine, 82 of which during pregnancy. Recently vaccinated women had significantly higher antibody titres (even 12–15 times as high) compared to those vaccinated more than 5 years before or never vaccinated at all (p < 0.0001). Moreover, 95.1% of recently vaccinated women had anti-PT IgG levels above 10 IU/ml, and 85.4% above 20 IU/ml, while the same proportions were as low as 37% and 21% (respectively) in the group of women not vaccinated in pregnancy. This study confirmed that the vaccination is greatly effective in ensuring high antibody titres in the first months after the booster vaccine, with considerable differences in anti-PT IgG compared to women vaccinated earlier or never vaccinated at all, and therefore vaccinating pregnant women against pertussis still represents a valuable strategy.     

Association between the timing of maternal vaccination and newborns’ anti-pertussis toxin antibody levels

BackgroundPertussis remains an important global public health concern, despite the presence of extensive immunization programs. Incidence and severity of pertussis are typically higher in neonates and young infants. As a strategy to protect these young infants, maternal vaccination with Tdap (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis) has been recommended in Brazil. The objective of this study was to evaluate the effects of Tdap vaccination during pregnancy on the anti-pertussis toxin (PT) IgG response in mothers and their infants at birth.Material and methodsMaternal and cord blood samples were collected from vaccinated (n = 243) and unvaccinated (n = 75) pregnant women, at the time of delivery, from July 2015 to August 2016 in São Paulo, Brazil. Anti-PT IgG antibodies were quantified by Enzyme-Linked Immunosorbent Assay (ELISA) and geometric mean concentrations (GMC) were calculated. Relationship between timing of vaccination and antibody concentrations were evaluated.ResultsMaternal and cord blood GMCs among the vaccinated group were 5.4 and 5.6 fold higher [66.5 International Units (IU)/mL and 89.8 IU/mL] compared to the unvaccinated group (12.4 IU/mL and 16.1 IU/mL), respectively (p < 0.001). Higher anti-PT IgG GMCs were observed when vaccination occurred ≥60 days before delivery compared to <60 days, suggesting that vaccination early in the third trimester may be more effective than later in pregnancy.ConclusionTdap maternal vaccination results in significantly higher anti-PT IgG in newborn infants and supports the current recommendation of the Brazilian Immunization Program.     

Combined tetanus-diphtheria and pertussis vaccine during pregnancy: transfer of maternal pertussis antibodies to the newborn

Background and objectivesPertussis is currently an emerging public health concern in some countries with high vaccination coverage. It is expected that maternal pertussis immunization could provide newborn protection. We compared pertussis toxin antibody (anti-PT) levels in women during pregnancy (pre- and post-vaccination) with respect to levels in the newborn at delivery in women vaccinated during pregnancy. We also estimated anti-PT titers at primary infant vaccination.MethodsObservational study of pregnant women vaccinated with Tdap (≥20 weeks gestation) and their newborns between May 2012 and August 2013. Anti-PT levels were determined by ELISA in maternal (pre- and post-vaccination) and newborn blood.ResultsPre-vaccination, post-vaccination maternal and newborn samples were available in 132 subjects. Mean maternal age was 34.2 (SD 4.3) years. Median weeks of gestation at vaccination were 27.2 (Q1–Q3 21.7–30.8). Anti-PT (≥10 IU/ml) levels were found in 37.1% of maternal pre-vaccination samples (geometric mean titer (GMT) 7.9 IU/ml (95% CI 6.8–9.2)), 90.2% of post-vaccination samples (GMT 31.1 IU/ml (95% CI 26.6–36.3)) and 94.7% of newborns (GMT 37.8 IU/ml (95% CI 32.3–44.1)). The Lin concordance index between post-vaccination maternal and newborn samples was 0.8 (95% CI 0.8–0.9). Transplacental transfer ratio was 146.6%. At two months of age, 66% of newborns had estimated anti-PT levels ≥10 IU/ml.ConclusionsThere was a high correlation between anti-PT levels in mothers and newborns, with higher levels in newborns, which should be sufficient to provide protection against pertussis during the first months of life. Vaccination of pregnant women seems to be an immunogenic strategy to protect newborns until primary infant immunization.     

Elucidating the difference in the kinetics of antibody titres of infants in Belgium and Vietnam

Serological results obtained in a single laboratory from twin-studies on maternal immunisation, in Vietnam and Belgium offer the opportunity to compare antibody kinetics in infants before and after infant vaccination in the presence of vaccine-induced maternal antibodies. Nonlinear mixed-effects models (NLMMs) making use of a hypothesised dynamic evolution that captures the change in antibody titres over time, were employed to model anti-PT and anti-Prn antibody dynamics. Our proposed modelling approach provided useful insight into understanding the differences in the infants’ antibody kinetics in both countries since NLMMs offer the possibility of pooling all data in one analysis and incorporate relevant covariates of interest.In both controlled cohort studies, pregnant women were vaccinated with a tetanus, diphtheria, acellular pertussis (Tdap) vaccine (Boostrix®, Belgium; Adacel®, Vietnam), and children were followed before and after primary vaccination, and before and after booster vaccination (Infanrix hexa®). From our models, both anti-PRN and anti-PT antibody titres at birth of Vietnamese infants were significantly lower than those of Belgian infants born to vaccinated women groups. Even though the antibody titres in the cord at birth of Belgian infants were also higher than those of Vietnamese infants born to the control women groups, the difference was not significant. The significant difference between infants born to vaccinated women in the two countries was likely due to the use of different vaccine brands in pregnant women and the different vaccination histories of women in these two countries.Our analyses also suggested that the blunting effect was present during the primary immunisation but went away afterward for anti-PT data. In contrast, for anti-PRN antibodies, the blunting effect persisted after the primary vaccination and possibly went away after the booster dose. Countries should be aware of the regional situation in view of recommending maternal immunization.     

Maternal pertussis and influenza immunization coverage and attitude of health care workers towards these recommendations in Flanders,Belgium

In Belgium, pertussis vaccination is recommended for all pregnant women in every pregnancy. Adults in close contact with young infants are equally advised to receive a pertussis containing booster dose. Maternal influenza vaccination is likewise recommended in Belgium in the second or third trimester of pregnancy, within the influenza season.A quantitative multicenter survey study has been performed between October 2014 and May 2015 in both postpartum women (N = 823, response rate = 89.2%) and health care workers (HCWs) (N = 261) to assess the coverage of both vaccines during pregnancy along with the coverage of the pertussis cocoon strategy, and to evaluate the knowledge and recommending attitude of HCWs towards the maternal vaccination strategies and the cocoon strategy among surveyed women and HCWs.Overall coverage of pertussis vaccination during pregnancy was 64.0%. Most women were vaccinated by their general practitioner (GP) (82.4%), and most often in the third trimester (74.0%) of pregnancy. Overall coverage of influenza vaccination during pregnancy was 45.0%. Again the GP administered most vaccines (67.6%); vaccines were equally administered in the second or third trimester of pregnancy. Educational level had a significant influence on both the pertussis and influenza vaccination coverage during pregnancy while working situation and parity had only an influence on the maternal pertussis vaccination coverage and country of birth only on the maternal influenza vaccination coverage.Overall, 78.4% of gynecologists and GPs recommends both maternal pertussis and influenza vaccination and 67.0% recommends both maternal vaccination strategies and the cocoon strategy. Within the group of the midwives, only 23.7% recommends both maternal pertussis and influenza vaccination and 10.5% recommends both maternal vaccination strategies and the cocoon strategy.High coverage is reached among pregnant women for pertussis and influenza vaccination. Several underserved populations of pregnant women regarding maternal immunization, are identified.     

Humoral and cell mediated immune responses to a pertussis containing vaccine in pregnant and nonpregnant women

Vaccination of pregnant women is recommended for some infectious diseases in order to protect both women and offspring through high titres of maternal IgG antibodies. Less is known on the triggering of cellular immune responses by vaccines administered during pregnancy. In an ongoing study on maternal pertussis vaccination (2012–2014) 18 pregnant women were vaccinated with a tetanus-diphtheria-acellular pertussis (Tdap) containing vaccine (Boostrix®) during the third pregnancy trimester. Sixteen age-matched nonpregnant women received the same vaccine in the same time period. A blood sample was taken at the moment of, but before vaccination and one month and one year after vaccination. Anti-Pertussis Toxin (PT), filamentous hemagglutinin (FHA), pertactin (Prn), tetanus toxin (TT) and diphtheria toxin (DT) antibodies were measured by ELISA. Cellular immune responses were analyzed using a diluted whole blood assay, measuring proliferation, and cytokine release in response to vaccine antigens PT, FHA, TT, and to pokeweed mitogen (PWM) as polyclonal stimulus.Antibody levels to all five vaccine components increased significantly and to the same extent after vaccination in pregnant and nonpregnant women. One year after vaccination, antibody titres had decreased particularly to PT, but they were still significantly higher to all antigens than before vaccination. In contrast, proliferative and IFN-γ responses were increased to TT, PT, and FHA in nonpregnant women one month after vaccination, whereas in pregnant women only TT specific T cell responses were increased and to a lesser extent than in the control group. One year after vaccination, cellular responses equaled the baseline levels detected prior to vaccination in both groups. In conclusion, a Tdap vaccination can increase vaccine specific IgG antibodies to the same extent in pregnant and in nonpregnant women, whereas the stimulation of vaccine specific Th1 type cellular immune responses with this acellular vaccine is transient and impaired during pregnancy.     

Influenza and pertussis vaccination coverage in pregnant women

BackgroundPregnant women have an increased risk for complications and hospitalizations when infected with the influenza virus in the second or third trimester. Additionally, infants under six months of age are most vulnerable when contracting pertussis. Immunization against influenza and pertussis during pregnancy provides protection for mother and neonate against influenza and for neonates against pertussis pending protection through infant immunization. In Belgium, a gradual increase in pertussis cases over the past decade was observed. This study was undertaken to document vaccination coverage for influenza and pertussis and factors related to vaccination status in pregnant women.MethodsTwo hundred and fifty pregnant women completed a questionnaire during their third trimester. Vaccination data were collected and reasons for non-vaccination were noted as well as socio-demographic data which are known to influence vaccination coverage.ResultsA documented vaccination coverage of 42.8% for influenza and 39.2% for pertussis was observed. Taking into account doses which were not documented, but administered according to the expectant mother, coverage for influenza would increase to 62% and for pertussis to 46%. The most important reasons for non-vaccination were the absence of a recommendation by medical staff (9.6%) and delay in vaccination (8.4%). The GP was the most important vaccinator. Pregnant women with a lower education and those with a foreign origin were more vulnerable for non-vaccination.ConclusionIncomplete documentation is the most important barrier in determining the vaccination status of pregnant women. Immunization during pregnancy needs further integration through vaccination campaigns aimed at both health care providers and pregnant women.     

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

BackgroundMaternal 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.ObjectivesThe 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).MethodsThis 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.ResultsThe 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).ConclusionMost 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.     

Immunogenicity of a liquid hexavalent DTaP-IPV-HB-PRP∼T vaccine after primary and booster vaccination of term and preterm infants born to women vaccinated with Tdap during pregnancy

BackgroundVaccination during pregnancy with tetanus, diphtheria, acellular pertussis (aP) (Tdap) antigens is important for early protection of newborn infants against pertussis, particularly for preterm infants. This study evaluated the effect of Tdap vaccination during pregnancy on the immunogenicity of a diphtheria (D), tetanus (T), aP, inactivated poliovirus (IPV), hepatitis B (HB), and Haemophilus influenzae type b (PRP ～ T) vaccine in term and preterm populations.MethodsA prospective, observational study (NCT02511327) recruited women and their infants based on delivery (term or preterm) and vaccination status (vaccinated with a Tdap vaccine [Boostrix?, GlaxoSmithKline] during pregnancy or not vaccinated in the last 5 years). All infants received licensed DTaP-IPV-HB-PRP ～ T (Hexyon?, Sanofi) (8, 12, 16 week primary series and booster at 13 months of age [preterm infants] or 15 months of age [term infants]). Immunogenicity was evaluated using validated assays. Data were pooled into term (N = 127) and preterm infants (N = 105), and infants of women who received a Tdap vaccine during pregnancy (N = 199) or not (N = 33).ResultsBefore primary vaccination, antibody levels were higher for term than preterm infants for anti-D, anti-polio 1, 2, 3, anti-PT, anti-FHA, and anti-PRP, and similar for anti-HBs and anti-T. At this time, infants of Tdap-vaccinated women had higher anti-D, anti-T, anti-PT, anti-FHA, and anti-PRP antibody levels than infants of Tdap-unvaccinated women; anti-HBs and anti-polio antibody levels were similar in both groups. Post-primary, pre-booster, and post-booster, there were only small differences in seroprotection rates (anti-D, anti-T, anti-polio 1, 2, 3, anti-HBs, anti-PRP) and seroconversion rates (anti-PT, anti-FHA), except for anti-HBs ≥ 10 mIU/mL and anti-PRP ≥ 0.15 µg/mL post-primary vaccination (higher for term [98.31 % and 90.91 %, respectively] versus preterm infants [89.80 % and 79.41 %, respectively]).ConclusionsThese data support the use of DTaP-IPV-HB-PRP ～ T vaccine for primary and booster vaccination in term and preterm born infants and in infants born to Tdap-vaccinated or Tdap-unvaccinated women.     

孕晚期GBS感染不良妊娠结局影响因素及IL-8水平

目的探讨孕晚期B族链球菌(GBS)感染血清降钙素原(PCT)、白细胞介素-8(IL-8)水平与妊娠结局的关系。方法选取2018年6月-2019年12月在杭州师范大学附属医院进行孕晚期(35~37周)GBS感染筛查的726例孕妇为研究对象,收集孕妇临床资料进行分析,统计GBS感染情况,比较GBS感染与未感染及不同GBS感染分级孕妇血清PCT、IL-8水平差异,单因素及多因素Logistic回归分析GBS感染孕妇不良妊娠结局的危险因素。结果 726例孕晚期女性中,GBS感染者占11.85%;GBS感染者年龄≥35岁、妊娠期糖尿病所占比例显著高于未感染者(P<0.05);孕晚期GBS感染者血清PCT、IL-8水平均高于未感染者(P<0.05),并随着GBS感染程度加重血清PCT、IL-8水平逐渐升高(P<0.05);孕晚期GBS感染者不良妊娠结局发生率显著高于未感染者(P<0.05),多因素Logistic回归分析结果显示,年龄≥35岁、血清PCT、IL-8水平升高是孕晚期GBS感染者不良妊娠结局发生的独立危险因素(P<0.05)。结论孕晚期GBS感染者血清PCT、IL-8水平显著升高,其也是不良妊娠结局发生的独立危险因素,血清PCT、IL-8进行联合检测对孕晚期GBS感染者不良妊娠结局具有较好的预测价值,可为临床早期诊疗提供参考依据。     

Anti-pertussis antibody kinetics following DTaP-IPV booster vaccination in Norwegian children 7–8 years of age

At the age of 7–8 years a booster of diphtheria, tetanus, acellular pertussis and polio vaccine is recommended for children in Norway. In this cross-sectional study we have analysed the antibody levels against pertussis vaccine antigens in sera from 498 children aged 6–12 years. The purposes of this study were to investigate the duration of the booster response against the pertussis vaccine antigens pertussis toxin (PT) and filamentous haemagglutinin (FHA); to determine the presence of high levels of pertussis antibodies in absence of recent vaccination; and to analyse how booster immunisation may interfere with the serological pertussis diagnostics. Prior to the booster the IgG antibody levels against PT revealed a geometric mean of 7.3 IU/ml. After the booster the geometric mean peak anti-PT IgG response reached to 45.6 IU/ml, followed by a steady decline in antibody levels over the next few years. The IgG anti-FHA levels followed the anti-PT IgG profiles. Three years after the booster the geometric mean IgG levels were only slightly above pre-booster levels. Prior to the booster 44% of the sera contained ≤5 IU/ml of anti-PT IgG compared to18% 3 years after and 30% 4 years after the booster. When recently vaccinated children were excluded, 6.2% of the children had anti-PT IgG levels above 50 IU/ml which may indicate pertussis infection within the last 2 years. This study indicates that the currently used acellular pertussis vaccines induce moderate immune responses to the pertussis antigens and that the antibodies wane within few years after the booster. This lack of sustained immune response may partly be responsible for the increased number of pertussis cases observed in this age group during the last years.     

The decline in immunity and circulation of pertussis among Chinese population during the COVID-19 pandemic: A cross-sectional sero-epidemiological study

BackgroundIn recent years, the resurgence of pertussis has posed a public health challenge in many countries. This study aimed to evaluate the immunity levels against pertussis among populations of different ages in China.MethodsWe conducted a cross-sectional serological survey in Zhejiang Province, China in 2020. Serum IgG antibodies against pertussis toxin (anti-PT), filamentous hemagglutinin (anti-FHA), and pertactin (anti-PRN) were quantitatively measured. The geometric mean concentration (GMC) of three antibodies was calculated. An anti-PT level < 5 IU/mL was considered undetectable, ≥20 IU/mL as seropositive and ≥80 IU/mL as an indicator of recent infection. Mathematical models were fitted for anti-PT concentrations over time in children after four doses of the pertussis vaccination.ResultsA total of 4459 participants aged 0–59 years were included in the analyses. The overall positivity rate of anti-PT was 29.80% with the highest (81.44%) rate in the 1–2 years old and the lowest (4.72%) in 10–14 years old. The GMCs of anti-PT, anti-FHA and anti-PRN for the whole participants were 9.67 (95%CI: 9.25–10.10),18.93 (18.24–19.67), and 8.99 (8.61–9.38) IU/mL, respectively. Over 50% of subjects aged ≥ 7 years had undetectable anti-PT IgG antibodies (<5IU/mL). The proportions of the populations with anti-PT IgG ≥ 80 IU/mL were approximately 0.9%, 0.3% and 1.1% among the 10–14, 15–29, and 40–59 years old groups, respectively. The power regression equation of the attenuation model after last dose of pertussis vaccine was y = 41.088x^-1.238 (R² = 0.935, p < 0.001). The fitted anti-PT concentrations was only 5.60 IU/mL at 5 years following the last vaccination dose.ConclusionThe prevalence of pertussis decreased during the study period in the COVID-19 pandemic; however, there was still a certain proportion of adolescents and adults with evidence of recent infection. The decline in antibody levels after pertussis vaccination was observed, and booster doses are in urgent need in China.     

Pertussis vaccination during pregnancy in Belgium: Results of a prospective controlled cohort study

Vaccination during pregnancy has been recommended in some countries as a means to protect young infants from severe infection. Nevertheless, many aspects are still unknown and possible blunting of the infant's immune responses by maternal antibodies, is one of the concerns with maternal vaccination. We report the first prospective controlled cohort study in women and infants on the effects of using Boostrix^®, a combined tetanus, diphtheria and acellular pertussis vaccine, during pregnancy. The primary aim was to measure the influence of this booster dose on the titer and duration of the presence of maternal antibodies in the infants and assess possible interference with infant immune responses.In a controlled cohort study, 57 pregnant women were vaccinated with Tdap vaccine (Tetanus Diphtheria acellular Pertussis, Boostrix, GSK Biologicals), at a mean gestational age of 28.6 weeks. A control group of pregnant women (N = 42) received no vaccine. Antibody geometric mean concentrations (GMCs) against tetanus (TT), diphtheria (DT), pertussis toxin (PT), filamentous haemagglutinin (FHA) and pertactin (Prn) were measured with commercial ELISA tests in samples taken preceding maternal vaccination and one month afterwards, at delivery and from the cord blood, and in infants before and 1 month after the primary series of 3 pertussis containing hexavalent vaccines.Infants born to vaccinated women had significantly higher GMC at birth and during the first 2 months of life for all vaccine antigens compared to the offspring of unvaccinated women, thereby closing the susceptibility gap for pertussis in infants. However, blunting was noticed for infant diphtheria and pertussis toxin vaccine responses (p < 0.001) in the infants from vaccinated women after the primary vaccination schedule (weeks 8,12 and 16).Since pertussis vaccination has been recommended during pregnancy already, the results of this study support that recommendation and provide additional scientific evidence to document possible interference by maternal antibodies.     

Influenza vaccination coverage among pregnant women --- United States, 2010-11 influenza season

Women are at increased risk for morbidity and mortality from influenza during pregnancy. Vaccinating pregnant women for influenza can protect both the women and their infants, especially infants aged <6 months who are not old enough to receive influenza vaccination. Since 2004, the Advisory Committee on Immunization Practices and the American College of Obstetricians and Gynecologists have recommended inactivated influenza vaccine for all women who are pregnant during influenza season, regardless of trimester. Before 2009, estimated influenza vaccination coverage among pregnant women had been consistently low (approximately 15%). However, vaccination levels increased substantially in response to the 2009 influenza A (H1N1) pandemic to nearly 50%. To estimate influenza vaccination coverage among pregnant women for the 2010-11 season, CDC analyzed data from an Internet panel survey conducted in April 2011 among women who were pregnant any time during October 2010-January 2011. Among 1,457 survey respondents, 49% reported that they had received influenza vaccination: 12% were vaccinated before pregnancy, 32% during pregnancy, and 5% after pregnancy. Women offered influenza vaccination by a health-care provider (62%) were more likely to be vaccinated (71%) than other women (14%) and were more likely to have positive attitudes about vaccine effectiveness and safety. These results indicate that the higher vaccination level achieved the previous season (2009-10) was sustained and emphasize the critical role of health-care providers in promoting influenza vaccination. Continued efforts are needed to encourage health-care providers to strongly recommend and offer influenza vaccination to pregnant patients to protect both the mothers and their infants.     

Pertussis vaccination during pregnancy in Vietnam: Results of a randomized controlled trial Pertussis vaccination during pregnancy

A pertussis vaccination during pregnancy has recently been adopted in several countries to indirectly protect young infants. This study assessed the effect of adding a pertussis component to the tetanus vaccination, in the pregnancy immunization program in Vietnam.A randomized controlled trial was performed. Pregnant women received either a Tdap (tetanus, diphtheria acellular pertussis) vaccine or a tetanus only vaccine between 19 and 35 weeks’ gestational age. Immunoglobulin G (IgG) against tetanus (TT), diphtheria (DT), pertussis toxin (PT), filamentous hemaglutinin (FHA) and pertactin (Prn) were measured using commercial ELISA tests, at baseline, 1 month after maternal vaccination, at delivery, and in infants from cord blood and before and after the primary series (EPI: month 2-3-4) of a pertussis containing vaccine.Significantly higher geometric mean concentrations (GMC) were observed for all 3 measured pertussis antigens in the offspring of the Tdap group, up to 2 months of age. One month after completion of the primary infant vaccination schedule, anti-Prn GMC, but not anti-PT and anti-FHA GMCs, was significantly (p = 0.006) higher in the control group.Maternal antibodies induced by vaccination during pregnancy close the susceptibility gap for pertussis in young infants. Limited interference with the infant vaccine responses was observed. Whether this interference effect disappears with the administration of a fourth vaccine dose is further studied.     

Pregnant women's intention to take up a post-partum pertussis vaccine,and their willingness to take up the vaccine while pregnant: A cross sectional survey

Introduction

Post-partum vaccination of new mothers is currently recommended in Australia to reduce pertussis infection in infants. Internationally, vaccination recommendations now include pregnant women in some countries. Understanding the awareness of pertussis vaccination recommendations among pregnant women, and their willingness to have the vaccine while pregnant is important for informing vaccine program implementation.

Objective

To determine awareness and intentions toward current recommendations for post-partum pertussis vaccination among Australian pregnant women, and their willingness to accept pertussis vaccine during pregnancy, should it be recommended in Australia in the future.

Design

Quantitative self-administered survey, using a non-random stratified sampling plan based on representative proportions by age, parity and region of residence.

Participants and setting

Pregnant women receiving antenatal care through three large, demographically diverse referral hospitals in metropolitan, urban and rural New South Wales, Australia.

Results

The response rate was 815/939 (87%). Most women (80%) reported willingness to have the pertussis vaccine during pregnancy, should it be recommended. Thirty four per cent of women intended to receive a pertussis vaccine post-partum, 17% had received it previously, while 45% had never heard of pertussis vaccine, had not thought about it, or were undecided about having it. Compared with those who had not received a recommendation to have the vaccine post-partum, women who had received a recommendation were 7 times more likely (95% CI 4–14) to report intention to have the vaccine.

Conclusions

Health care provider recommendation is paramount to raising awareness of pertussis vaccination recommendations among pregnant women. Women's willingness to have the vaccine while pregnant is encouraging, and indicates the potential for high pertussis vaccine coverage among pregnant women, should it be recommended in Australia.     

Determination of circulating antibodies directed to pertussis toxin and of agglutinogens in children vaccinated with either the whole cell or component pertussis vaccine in France, Japan and Senegal.

The antibody response to pertussis toxin (PT) and agglutinogens of children vaccinated in Japan, France and Senegal with either whole cell or component pertussis vaccine was determined at various times after immunization. Agglutinin titres were almost similar in sera of Japanese children vaccinated with either whole cell or component pertussis vaccine whereas anti-PT antibody levels were found to be higher after vaccination with whole cell vaccine than with component vaccine. The geometric mean (GM) agglutinin titres in sera of Japanese children amounted to 45.0 and 45.7, respectively, and neutralization GM titres to 71.6 and 22.6, respectively, following vaccination with the whole cell and component pertussis vaccines. Sera of French children receiving three doses of whole cell vaccine exhibited a GM agglutinin titre of 17.8, whereas only 16% of sera contained neutralizing antibodies against PT. Following the booster dose the GM agglutinin titre rose to 213.5 and 68% of the sera contained neutralizing antibodies to PT (GM titre 48.0). Sera of Senegalese children receiving three doses of whole cell vaccine exhibited a GM agglutinin titre of 18.7, whereas anti-PT neutralizing antibodies were hardly detected. Agglutinins and anti-PT antibody in sera of French and Senegalese children turned out to be lower than were found 25 years ago in sera of children immunized with the French whole cell pertussis vaccine.     

Pertussis vaccination during pregnancy: Antibody persistence in infants

Maternal pertussis vaccination is associated with higher levels of pertussis antibodies at birth. We assessed the persistence of pertussis antibodies until primary vaccination in infants whose mothers received Tdap (tetanus, diphtheria, acellular pertussis) vaccine during pregnancy. Infants were born at the Hospital Clinic of Barcelona (Spain) in November 2014. Anti-PT IgG was determined by ELISA at delivery, between the first and second month of life, and estimated at 2 months of age. The study included 37 infants whose mothers received Tdap between 21 and 38 weeks of gestation. Infants presented a decline in GMC of anti-PT IgG between peripartum and follow-up levels, 52.7 (95% CI 34.7–80.2) versus 7.5 (95% CI 4.2–13.3) at 2 months of age (p < 0.001). The median half-life of maternal antibodies was 47 days. More than half (51.4%) the infants presented detectable anti-PT IgG before the start of primary infant vaccination.     

Seroprevalence of IgG antibodies to pertussis toxin in children and adolescents in Estonia

Background and aims

Despite high immunisation coverage and frequent booster doses, the national notification rates of pertussis in Estonia have been increasing. The peak of 97/100,000 was reached in 2010 which is the highest incidence rate since 1962 (210/100,000).We aimed to measure the prevalence of pertussis toxin (PT) IgG type antibodies in subjects of <18 years and to estimate the pertussis infection activity in a recently non-immunised cohort.

Methods

In a cross-sectional serosurvey, all consecutive leftover sera were collected in the Tartu University Hospital during April–August 2012. Anti-PT IgG concentration was measured by commercial ELISA and analysed in yearly cohorts. The antibody concentrations ≥62.5 IU/mL was considered suggestive to pertussis in the last year among 9- to 14-year-olds.

Results

The GMC of the anti-PT-IgG was 7.4 IU/mL (95% CI 6.9–8.0). In the total of 1053 serum samples, the highest proportion of sera with high antibody titres ≥125 IU/mL and ≥62.5 IU/mL were at the ages when pertussis vaccine boosters were given: 7 years 10.9% (95% CI 4.1–22.3) and 2 years 36.9% (95% CI 25.3–49.8), respectively. Approximately half of all sera had undetectable anti-PT IgG levels. The estimated incidence of Bordetella pertussis infection among 9- to 14-year-olds in the year before serum sampling was 6.3% (95% CI 3.3–10.8), which is at least 60 times higher than the officially reported incidence of pertussis disease in respective years.

Conclusions

The serologic method is not suitable for diagnosing pertussis in instances when the last pertussis immunisation was less than one year ago. The relatively high proportion of subjects with undetectable anti-PT IgG levels and the relatively low rate of officially reported pertussis cases suggest that low antibody levels do not necessarily indicate the absence of protection. The estimated incidence rate of pertussis is much higher than officially reported figures, which suggests that asymptomatic/mild B. pertussis infection remains unrecognised and unreported.     

Effect of maternal immunization against pertussis in Medellin and the metropolitan area,Colombia, 2016–2017

BackgroundIn 2013, pertussis immunization (Tdap) for pregnant women was implemented in Colombia to protect newborns in response to increased pertussis incidence.ObjectiveTo assess the effect of Tdap maternal immunization on the concentration of mother/umbilical cord antibodies and the occurrence of pertussis in infants during their first six months of life.MethodsA cohort study in eight randomly selected hospitals in Medellin and metropolitan area of Antioquia, Colombia was conducted in 2015–2016. IgG PT antibody levels in paired maternal and umbilical cord sera were measured from 805 mothers immunized recruited during labor and 200 mothers recruited during the prenatal care before immunization and followed until delivery. Antibodies were analyzed by commercial ELISA kits. 896 infants were followed to detect acute respiratory infections and paroxysms of coughing, inspiratory whoop, apnea, cyanosis or post-tussive vomiting. For laboratory confirmation, B. pertussis- specific real time PCR was performed.ResultsWe observed a high prevalence of titers >100 IU/mL (mother: 18.40% [95% CI 16–21%]; umbilical cord: 23.1% [95% CI 19.2–27.4%]), positive correlation of umbilical cord and maternal antibodies, higher antibody concentration in vaccinated than in non-vaccinated mothers and significant difference in antibody levels before and after vaccination (Wilcoxon test p = 0.000). The trans placental transport ratio was higher if the mother was vaccinated between 26 and 30 weeks of pregnancy and maximum eight weeks before delivery. Two cases of pertussis were confirmed in infants (incidence of 1.99 per 1000).ConclusionThe expected effect of Tdap maternal vaccination against pertussis was observed.