Recommendations are needed for adolescent and adult pertussis immunisation: rationale and strategies for consideration

The seroepidemiology of immunoglobulin G antibodies against pertussis toxin and filamentous hemagglutinin in the east of China during the COVID-19 pandemic

This study employed sero-epidemiological methods to estimate the incidence of pertussis within a healthy population located in eastern China. The aim was to gain deeper insights into the epidemiological characteristics and burden of pertussis within the country. Blood samples were collected from healthy individuals in Jiangsu Province between June 2019 and December 2022. The levels of IgG antibodies against pertussis toxin (anti-PT) and filamentous hemagglutinin (anti-FHA) in the serum were quantitatively measured using enzyme-linked immunosorbent assay (ELISA). Additionally, pertussis case data reported in Jiangsu Province were collected from the China Information System for Disease Control and Prevention and compared with the results of this study. In 2022, the reported incidence of pertussis stood at 1.0 per 100,000 individuals, marking the highest rate observed in the past two decades. Among 1,909 patients examined, the geometric mean concentration (GMC) of anti-PT IgG antibody was 20.2 (18.5-21.9) IU/ml, while that of anti-FHA IgG antibody was 27.0 (25.4-28.7) IU/ml. The IgG-PT and IgG-FHA seropositivity rate (>20.0 IU/ml) was highest in the 1 ~ 2 y old group and decreased rapidly to the lowest in the 3 ~ 4 y old group and then increased gradually with age. The estimated rate of pertussis infection based on seroprevalence was approximately 25,625-fold higher than the reported notification rate in the ≥15 year age group. Our findings highlight decreased immunity post-vaccination, stressing the importance of additional booster shots for adolescents and adults to maintain immunity and reduce severe illness. Additionally, they offer vital guidance for policymakers to enhance immunization strategies.

Seroepidemiology of pertussis in the east of China: Estimates of incidence of infection in adolescents and adults pre- and post-COVID-19

Introduction

The dramatic decrease in the number of reported cases of pertussis during COVID-19 pandemic has been underestimated. The objective was to compare the estimated incidence rate of pertussis in populations pre- and post-COVID-19 pandemic by analyzing the anti-pertussis toxin (anti-PT) IgG and anti-filamentous hemagglutininant (anti-FHA) IgG antibodies in healthy Chinese population from 2018 to 2021.

Methods

All serum samples (N = 1,000) were collected from healthy population (aged ≥ 15 years) who attended an annual monitoring project of antibody levels in Jiangsu province in 2018-2021 were measured by ELISA.

Results

The positive rates of anti-PT IgG and anti-FHA IgG antibodies were 11.4% (114/1,000) and 20.2% (202/1,000) (≥40 IU/ml), the GMC were 17.25 (95% CI: 15.49-19.03) IU/mL and 24.94 (95% CI: 22.73-27.16) IU/mL in the study population, respectively. The percentage of participants with anti-PT IgG antibodies higher than 40 IU/mL was 5.20% (11/212) in 2018, 5.5% (19/348) in 2019, 21.2% (46/217) in 2020 and 17.0% (38/223) in 2021, respectively. The non-detectable rate (<5 IU/mL) of anti-PT IgG antibodies was 16.9, 17.7, 28.1, and 37.3% in 2018, 2019, 2020, and 2021, respectively. We assumed that the infection occurred within 58.6 days, and based on the overall proportion (2.9%) of individuals with anti-PT IgG antibody ≥100 IU/ml, the incidence rate (/100) was estimated by the formula to be 18.08 (95% CI: 12.40-26.11). In addition, the estimated incidence of Post-COVID-19 was higher than that of Pre-COVID-19 (36.33/100 vs. 12.84/100), and the difference was statistically significant (p < 0.05).

Conclusions

Our results suggest a high rate of under-reporting of pertussis in Jiangsu Province both pre- and post-COVID-19 pandemic, and there are a large number of adults of childbearing age who are susceptible to pertussis. It seems imperative that vaccination of adolescents and adults should be considered for inclusion in vaccination programs.

Seroepidemiology of pertussis in China: A population-based, cross-sectional study

BACKGROUND

Despite high pertussis vaccination coverage and significant decrease of pertussis since the adoption of the Expanded Programme on Immunization (1978), increased pertussis incidence has been reported in China from 2013 to 2017. This study aimed at evaluating the immune response to pertussis among vaccinated children and beyond in China.

METHODS

The study recruited 2 144 healthy subjects. Serum IgG antibodies against pertussis toxin (anti-PT IgG) were measured by ELISA. Anti-PT IgG concentration (GMC), seropositivity rate (GMC ≥ 40 IU/ml), and recent infection rate (GMC > 100 IU/ml) were calculated. Participants ≤ 2 years-old were further stratified by vaccination schedule intervals and participants ≤ 6 years-old by vaccine used (Domestic DTaP or DTaP-IPV//PRP ~ T (Pentaxim, SP)).

RESULTS

Among 0-6-year-olds, the anti-PT IgG GMC was 5.99 IU/ml (95%CI 5.39-6.67). The GMC increased in accordance with the primary vaccination series (4-6 months) and the toddler booster (18-23 months), and continuously declined thereafter to its nadir at 6 years-old [3.72 IU/ml (95%CI 2.91-4.77)]. GMCs were markedly higher in those vaccinated with DTaP-IPV/PRP ~ T compared to DTaP. In individuals > 6 years-old, the GMC was 5.67 IU/ml (95%CI 5.36-6.00), the seropositivity rate was 6.7% (95%CI 5.5-7.9) and the recent infection rate was 1.2% (95%CI 0.7-1.7). The seropositivity rates increased from 6 years-old and peaked at 9 years-old (10.3% [95%CI 0.7-19.8]).

CONCLUSIONS

Vaccination against pertussis increases anti-PT IgG, but wanes over time. The sero-estimated infection rates increase from school age and peak at about 9 years-old. These results support the addition of a booster of pertussis vaccine at preschool age.

A phase-I, open label clinical trial to assess the safety of Tdap vaccine manufactured by Serum Institute of India Pvt. Ltd. in adults

BACKGROUND

This first in human study was designed as an open label clinical trial to assess the safety and tolerability of Serum Institute of India Pvt. Ltd. (SIIPL) Tdap vaccine in healthy adult volunteers, aged 18-45 years.

METHODS

A total of 24 healthy adults were administered a 0.5 ml single dose of SIIPL Tdap vaccine intramuscularly, and were followed for one month for safety outcomes viz., immediate, solicited, unsolicited and serious adverse events.

RESULTS

23 subjects completed the study in compliance with the study protocol. None of the participants experienced any immediate adverse events or any local or systemic solicited adverse events.

CONCLUSION

Tdap vaccine manufactured by Serum Institute of India Pvt. Ltd. is safe and well tolerable in adults. It was concluded that further clinical development of this vaccine should continue to assess its safety and immunogenicity, in the target population. Clinical Trial Registration - CTRI/2017/03/008003.

Evaluation of immunisation strategies for pertussis vaccines in Jinan, China - an interrupted time-series study

Studies in countries with high immunisation coverage suggest that the re-emergence of pertussis may be caused by a decreased duration of protection resulting from the replacement of whole-cell pertussis vaccine (WPV) with the acellular pertussis vaccine (APV). In China, WPV was introduced in 1978. The pertussis vaccination schedule advanced from an all-WPV schedule (1978-2007), to a mixed WPV/APV schedule (2008-2009), then to an all-APV schedule (2010-2016). Increases in the incidence of pertussis have been reported in recent years in Jinan and other cities in China. However, there have been few Chinese-population-based studies focused on the impact of schedule changes. We obtained annual pertussis incidences from 1956 to 2016 from the Jinan Notifiable Conditions Database. We used interrupted time series and segmented regression analyses to assess changes in pertussis incidence at the beginning of each year, and average annual changes during the intervention. Pertussis incidence decreased by 1.11 cases per 100 000 population (P = 0.743) immediately following WPV introduction in 1978 and declined significantly by 1.21 cases per 100 000 population per year (P < 0.0001) between 1978 and 2001. Immediately after APV replaced the fourth dose of WPV in 2008, the second and third doses in 2009, then replaced all four doses in 2010, pertussis incidence declined by 1.98, 1.98 and 1.08 cases per 100 000 population, respectively. However, the results were not statistically significant. There were significant increasing trends in pertussis incidence after APV replacements: 1.63, 1.77 and 1.78 cases/year in 2008-2016, 2009-2016 and 2010-2016, respectively. Our study shows that the impact of an all-WPV schedule may be less than the impacts of the sequential WPV/APV schedules. The short-term impact of APV was better than that of WPV; however, the duration of APV-induced protection was not ideal. The impact and duration of protective immunity resulting from APVs produced in China need further evaluation. Further research on the effectiveness of pertussis vaccination programme in Jinan, China is also necessary.

Immunization against pertussis in adolescents and adults

Pertussis is a highly contagious infectious disease caused by Bordetella pertussis that can be extremely serious, particularly in young infants. For many years the efforts of health authorities throughout the world to prevent pertussis had the main goals of reducing the morbidity of infants and children under 5 years of age, maintaining protection for several years during the school-age period and developing a significant herd immunity to directly and indirectly reduce the risk of the spread of the disease among young infants and the risk of transmission of the infection from preschool children to infants. However, the increased risk of B. pertussis infection among adolescents and adults due to the waning immunity to this bacterium induced by vaccines and natural infection seems to be the main reason for the resurgence of pertussis. We discuss the reasons for the administration of pertussis vaccines to individuals for whom they were previously not recommended, the expected results of the administration of additional pertussis vaccine doses and the differences in the administration of pertussis vaccines in different countries. An analysis of the literature revealed several reports indicating the need for the modification of immunization schedules against pertussis, with booster doses among adolescents and the need for the vaccination of pregnant women. However, to monitor the true epidemiology of pertussis, effective programmes to collect pertussis cases, adequate reporting systems and vaccination coverage monitoring should be urgently implemented.

Tendencia de la mortalidad y morbilidad por tos ferina en Colombia 2002-2012

<p class="Default"><strong>Introducción.</strong> La tos ferina es un problema de salud pública que afecta principalmente a niños menores de un año en quienes los desenlaces son altamente letales; es una enfermedad reemergente, prevenible con inmunización.</p><p><strong>Objetivo.</strong> Analizar la tendencia de la mortalidad y morbilidad por tos ferina en Colombia entre los años 2002-2012.</p><p><strong>Materiales y métodos.</strong> Estudio descriptivo cuantitativo de las muertes por tos ferina entre 2002-2012 con fuente de información secundaria según certificados de defunción del Departamento Administrativo Nacional de Estadística, y casos reportados al Sistema Nacional de Vigilancia en Salud Pública 2005-2012. Se calcularon medidas de frecuencia, tasas de morbilidad y mortalidad y sobremortalidad femenina.</p><p><strong>Resultados.</strong> El 51,2% de las muertes ocurrieron en mujeres; el año con más defunciones fue 2012; el 67,3% pertenecían al área urbana y el 43,5% estaban afiliados al régimen subsidiado de salud. El riesgo de enfermar fue de 1,88 por mil nacidos vivos con mayor riesgo en Vaupés y Vichada. El riesgo de morir fue de 0,02 por mil nacidos vivos; la tendencia de la letalidad mostró disminución.</p><p><strong>Conclusión.</strong> La mortalidad y morbilidad por tos ferina ha mostrado reemergencia; al ser esta una enfermedad prevenible por medio de la vacunación se recomienda mayor control y mejora en las coberturas de vacunación tanto en niños como en adultos que son un importante reservorio de la enfermedad; para un efectivo control de la tos ferina se recomienda un trabajo continuo orientado a su identificación oportuna; también es preciso adelantar acciones para mejorar la calidad del dato con el fin de facilitar análisis y generación de información cada vez más válida.</p>

Protecting Newborns Against Pertussis: Treatment and Prevention Strategies

Pertussis is a potentially severe respiratory disease, which affects all age groups from young infants to older adults and is responsible for an estimated 195,000 deaths occurred globally in 2008. Active research is ongoing to better understand the pathogenesis, immunology, and diagnosis of pertussis. For diagnosis, molecular assays (e.g., polymerase chain reaction) for detection of Bordetella pertussis have become more widely available and support improved outbreak detection. In children, pertussis vaccines have been incorporated into routine immunization schedules and deployed for pertussis outbreak control. Lower levels of vaccine coverage are now being observed in communities where vaccine hesitancy is rising. Additionally, recognition that newborn babies are at risk of pertussis in the USA and UK has led to recommendations to immunize pregnant women. Among adolescents and older adults in the USA, Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular pertussis (Tdap) Vaccines are recommended, but substantial individual- and system-level barriers exist that will make achieving national Healthy People 2020 targets for immunization challenging. Current antimicrobial regimens for pertussis are focused on reducing the severity of disease, reducing rates of sequelae, and minimizing transmission of infection to susceptible individuals. Continued surveillance for pertussis will be important to identify opportunities for reducing young infants' exposure and reducing the impact of outbreaks among school-aged children. Laboratory-based surveillance for newly emerging strains of B. pertussis will be important to identify strains that may evade protection elicited by currently available vaccines. Efforts to develop new-generation pertussis vaccines should be considered now in anticipation of vaccine development programs, which may require ten or more years to deliver a licensed vaccine.

[Pertussis vaccine. Reemergence of the disease and new vaccination strategies]

Pertussis continues to be a public health problem despite the significant decrease in its incidence due to routine vaccination. Resurgence of the disease in countries that have maintained high vaccination coverage has been observed in recent years. Although vaccination is the most effective preventive control measure, both natural and artificial immunity wane over time, and thus the protection offered by current vaccines is not long-lasting. Furthermore, acellular vaccines are less effective. The implementation of new vaccine strategies is required. Vaccination of pregnant women is the most effective strategy for preventing pertussis in young infants, who are the most vulnerable, and should be recommended together with cocooning, ie vaccination of future household and extra-domiciliary contacts who are the main transmitters of the disease.

Adolescent vaccines: Need special focus in India

WHO defines adolescence age between 10 to 19 years. In India, there are 243 million adolescents which constitute 21 per cent of the total population. The global burden of disease in adolescents (2011) reports that the total number of disability adjusted life years (DALYs) worldwide among adolescents were 230 million which constitutes 15.5% of total DALYs. The immunization is one of the most important, most beneficial and cost-effective disease prevention measures that can be provided for adolescents. The adolescent vaccination protects most of the world's adolescents from a number of infectious diseases that previously claimed millions of lives each year. In India, thousands of adolescents die and thousands are hospitalized every year due to communicable diseases that could have been prevented by vaccination. Main aims of adolescent vaccinations are: to boost immunity status that is waning after completion of primary immunization or absence of "natural" boosting due exposure to the particular disease. The recommendations for the immunization of adolescents are to improve vaccination coverage among them. The adolescent vaccinations also help in accelerate disease control or elimination effort. Improvement in adolescent immunization coverage in India, will require strengthening of health care delivery system and also require significant improvements in the health care functionaries ability and willingness to provide and deliver vaccines to adolescents.

Pertussis seroprevalence in korean adolescents and adults using anti-pertussis toxin immunoglobulin G

This study was conducted to evaluate age-specific seroprevalence of pertussis in Korea and to formulate a strategy to prevent and reduce the incidence of pertussis. Residual serum samples of healthy adolescents and adults 11 yr of age or older were collected between July 2012 and December 2012, and anti-pertussis toxin (PT) IgG titers were measured using a commercial ELISA kit. We compared the mean anti-PT IgG titers and seroprevalence of pertussis of the six age groups: 11-20, 21-30, 31-40, 41-50, 51-60, and ≥ 61 yr. A total of 1,192 subjects were enrolled. The mean anti-PT IgG titer and pertussis seroprevalence were 35.53 ± 62.91 EU/mL and 41.4%, respectively. The mean anti-PT IgG titers and seroprevalence were not significantly different between the age groups. However, the seroprevalence in individuals 51 yr of age or older was significantly higher than in individuals younger than 51 yr (46.5% vs 39.1%, P = 0.017). Based on these results, a new pertussis prevention strategy is necessary for older adults.

Assessing the impact of a pertussis active surveillance program on provider testing behavior, Minnesota 2005-2009

OBJECTIVES

The Minnesota Department of Health, in collaboration with the Centers for Disease Control and Prevention, implemented the Pertussis Active Surveillance Project to better understand pertussis epidemiology. We evaluated the program's impact.

METHODS

Clinics in 2 counties were offered free diagnostic testing and an educational presentation covering pertussis epidemiology. Clinics were identified as either active or intermittent, with active clinics testing 33% or more of the total number of months enrolled. We used generalized estimating equations to assess changes in provider testing behavior over the project period.

RESULTS

Ninety-seven clinics enrolled, with 38% classified as active. Active clinics were more likely to use the state lab for diagnostic testing and had a larger staff. During the project period, a decline in days coughing at the time of visit occurred in both jurisdictions.

CONCLUSIONS

Providing clinics with free diagnostic testing influenced their participation levels. Among active clinics, results suggest changes in provider testing behavior over the course of the project. However, given the lack of robust participation, this resource-intensive strategy may not be a cost-effective approach to evaluating trends in pertussis epidemiology.

Pharmacist-led Tdap vaccination of close contacts of neonates in a women's hospital

BACKGROUND

Pertussis can cause severe illness and death in infants. Immunization of family members with the tetanus toxoid, reduced diphtheria toxoids, and acellular pertussis (Tdap) vaccine can decrease risk of pertussis infection among infants. A community pharmacy on a women's hospital campus implemented a Tdap vaccination pilot program.

OBJECTIVE

To investigate the rate of Tdap vaccination among close contacts of neonates in a women's hospital pharmacy and to assess the impact of a coordinated pharmacy and hospital Tdap vaccination program.

METHODS

The intervention entailed education from hospital staff who explained the risks of pertussis, advocated the benefits of vaccination, and encouraged family members to be vaccinated. In the on-site clinic or in the pharmacy, pharmacists administered vaccine to eligible patients. Rates of Tdap vaccinations in the intervention pharmacy with in-hospital vaccination were compared to comparison pharmacies without Tdap interventions.

RESULTS

In the pre-study period (December 2008-November 2010), there were 31 Tdap vaccinations administered at the intervention pharmacy (mean=1.3/month); during the study period (December 2010-November 2012), 2045 Tdap vaccinations were administered (mean=85.2/month). In four comparison hospital-campus pharmacies, there were 77 vaccinations (mean=0.8/month) during the pre-study period and 817 vaccinations (mean=8.5/month) during the study period. There were 155 vaccinations administered in 44 area-community pharmacies (mean=0.1/month) during the pre-study period and 2930 (mean=2.8/month) during the study period. The intervention pharmacy had the highest average monthly rate of change in Tdap volume from pre-study to study period (83.9), compared to comparison hospital-campus pharmacies (7.7, p<.001) and area-community pharmacies (2.7, p<.001). During the study period, the estimated Tdap vaccination coverage per live births was 8.1% in the intervention pharmacy versus 5.5% in the comparison hospital-campus pharmacies (p<.001).

CONCLUSIONS

Tdap vaccination rates increased after implementation of the intervention program. This project illustrates how health systems and community pharmacists can collaborate to improve patient care.

Should acellular pertussis vaccine be recommended to healthcare professionals?

The aim of this study was to describe recent changes in the epidemiology of pertussis and existing policies regarding recommended and mandatory occupational vaccinations for healthcare professionals (HCPs). The authors carried out an extensive review of references on the PubMed and SciELO databases and the official sites of the World Health Organization, Pan American Health Organization, Centers for Disease Control and Prevention, and Brazilian Ministry of Health, using the keywords pertussis, vaccines and healthcare professionals. Vaccination against pertussis is recommended for HCPs in the United States, Canada, nine European countries, Australia, Hong Kong, Singapore, Costa Rica, Argentina and Uruguay, and in some countries it is compulsory. In Brazil, only one publication discussing the risk of pertussis among HCPs was found. Considering the reemergence of pertussis and the great number of associated hospitalizations and deaths registered in 2011, it is necessary to review public policies regarding HCP pertussis vaccination, particularly among workers in frequent contact with young babies.

Immunogenicity and reactogenicity of two diphtheria-tetanus-whole cell pertussis vaccines in Iranian pre-school children, a randomized controlled trial

The present study was undertaken to compare the immunogenicity and reactogenicity of two diphtheria-tetanus-whole cell pertussis (DTwP) vaccines administered to Iranian preschool children. In this randomized, double-blind and multicenter prospective study, 672 children aged 4-6 y were administered with either a local DTwP vaccine (DTwP-Local) (n = 337) or a commercial vaccine (DTwP-Pasteur) (n = 335). All subjects received DTwP vaccine at 4-6 y of age, following the national immunization schedule of Iran. Blood samples were collected before and 2-4 weeks after the vaccination. Immunogenicity of each vaccine was assessed by ELISA using commercial kits. Reactogenicity was assessed by the parents for seven days post-booster using diary cards. The geometric mean titers (GMTs) of the antibodies induced against diphtheria and tetanus by DTwP-Local were 7.7 and 9.4 IU/ml and those of DTwP-Pasteur were 8.2 and 8.6 IU/ml, respectively. There was no significant difference between the immunogenicity of the two vaccines against diphtheria and tetanus. The GMTs of antibodies produced against pertussis were 30.2 EU/ml for DTwP-Local and 47.9 EU/ml for DTwP-Pasteur vaccines (p<0.001). Pain and fever (axillary temperature>37.5°C) were the most frequent local and systemic reactions observed after the vaccination. All local and systemic reactions observed after vaccination were significantly higher in subjects immunized with DTwP-Local vaccine. Immunogenicity against diphtheria and tetanus was similar for the two vaccines, but immunogenicity of the local vaccine against pertussis was significantly less efficient than that of DTwP-Pasteur. This difference and the higher side effects of the DTwP-Local vaccine could be due to the bacterial strain or the preparation or formulation protocol of the local pertussis vaccine.

Hospitalizations for pertussis in Italy, 1999-2009: analysis of the hospital discharge database

Even if the incidence of pertussis has greatly decreased after the adoption of immunization, it still remains a relevant cause of death in infants in their first years of life. At national level, data are usually greatly underestimated. The objective of this study was to retrospectively review the national hospital discharge form database. The national database was retrospectively searched using the International Classification of Diseases, ninth revision, Clinical Modification system. In the period 1999-2009, 7,768 hospitalizations for pertussis (primary diagnosis) have been registered: 6,971 hospitalizations and 797 day hospital admissions. The annual mean was equal to 633.6 hospitalizations and 72.4 day hospital admissions. The majority of hospitalizations (57.4 %) involved subjects <1 year of age; the mean duration of stay was about 6 days. Conclusion These data, even if restricted to hospitalizations registered at national level, confirm the epidemiological impact of pertussis and its complications in a country with a consistently high vaccination coverage rate.

The seroepidemiology of immunoglobulin G antibodies against pertussis toxin in China: a cross sectional study

Background

Pertussis is a reported vaccine-preventable respiratory disease in China. Because the routine laboratory methods for diagnosis are not in use, the reported cases are mainly in infants with classical paroxysmal cough and the true incidence related to pertussis is most likely under estimated. In China, however, few studies have attempted to address this issue. The purpose of this cross sectional study was to estimate the incidence rates using the method of sero-epidemiology of immunoglobulin (Ig) G antibodies against pertussis toxin (PT) among healthy populations in China.

Methods

Blood samples were obtained from 1313 healthy individuals aged 0 to 95 years in Guangdong province of China throughout September 2010. Serum IgG antibodies against PT were determined by commercial ELISA kits. Subjects with concentration of anti-PT IgG higher than 30 IU/mL were indicated to have recent Bordetella pertussis infection, if they have not received a booster dose of pertussis vaccine within one year.

Results

Of the 1313 study subjects, 117 (8.91%) were found to have anti-PT antibodies higher than 30 IU/mL. The estimated incidence of recent infection was thus 9395 per 100,000 for individuals older than 7 years. Peaks of the estimated incidence rate of recent infection were found to be 11561 per 100,000 in age group of 41–50 years and 11428 per 100,000 in the group aged 13–19 years.

Conclusions

Our study indicated that B.pertussis infections are considerablely common, particularly in adolescents and adults in China. The study also stresses the importance of laboratory diagnosis for pertussis and employment of booster dose of pertussis vaccine in adolescents and adults in this country.

Humoral immunity 10 years after booster immunization with an adolescent and adult formulation combined tetanus, diphtheria, and 5-component acellular pertussis vaccine

Persistence of antibodies after a single dose of Tdap vaccine (tetanus, diphtheria, and 5-component acellular pertussis vaccine) was evaluated in a follow-up study 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 concentrations. Humoral immune responses to all antigens were robust 1 month after initial immunization, decreased at subsequent measurements, but continued to exceed pre-immunization levels 1, 3, 5, and 10 years later. Protective levels of diphtheria and tetanus antitoxin persisted in 99.3% of adolescents 10 years after a booster dose of Tdap. Seropositivity to 1 or more pertussis antigens also persisted in most adolescents for 10 years. Although tetanus antitoxin responses were similar in adults to those observed in adolescents, diphtheria antitoxin titers were lower, reflecting the fact that a smaller proportion of adults had received diphtheria toxoid in the previous 10 years compared to adolescents. These data will contribute to the selection of the optimal interval for repeat doses of Tdap.

Immune responses in adults to revaccination with a tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine 10 years after a previous dose

BACKGROUND

Although decennial adult boosters of tetanus and diphtheria toxoids are recommended in Canada and the United States, a second dose of pertussis vaccine during adulthood is not currently recommended.

METHODS

This open-label, multicenter study compared the safety and immunogenicity of a first dose of an adult formulation of tetanus, diphtheria, and acelluar pertussis vaccine (Tdap) with a repeat dose of Tdap in adults who had received Tdap 10 years previously.

RESULTS

A total of 769 participants ranging in age from 20 to 72 years took part in this study; 92.3% of naïve and 92.7% of repeat-dose participants had at least one solicited adverse event. Injection-site pain (84.4% and 87.8%), erythema (29.7% and 23.1%), and swelling (23.3% and 20.5%), and myalgia (53.5% and 60.1%), headache (37.6% and 40.6%), malaise (29.0% and 29.4%), and fever (4.9% and 4.2%) were the most common solicited adverse events reported in the naïve and repeat-dose groups, respectively. Postvaccination antibody levels ≥0.1 IU/mL were achieved by 99.7% of the naïve-group participants and all of the repeat-dose participants for tetanus and 96.1% of the naïve group and 98.5% of the repeat-dose group for diphtheria, both meeting the predefined noninferiority criteria. For pertussis antibodies, anti-PT (89.2 EU/mL vs. 116 EU/mL) was higher in the repeat-dose group, anti-FHA (249 vs. 214) and anti-PRN (216 vs. 266) were similar, and anti-FIM (1015 vs. 779) was higher in the naïve group. Noninferiority criteria were met for all antigens except for anti-FIM.

CONCLUSION

A repeat dose of Tdap vaccine 10 years after the first dose was well tolerated and immunogenic in adults (ClinicalTrials.gov identifier: NCT00712959).

Antibody response from whole-cell pertussis vaccine immunized Brazilian children against different strains of Bordetella pertussis

Bordetella pertussis is a gram-negative bacillus that causes the highly contagious disease known as pertussis or whooping cough. Antibody response in children may vary depending on the vaccination schedule and the product used. In this study, we have analyzed the antibody response of cellular pertussis vaccinated children against B. pertussis strains and their virulence factors, such as pertussis toxin, pertactin, and filamentous hemagglutinin. After the completion of the immunization process, according to the Brazilian vaccination program, children serum samples were collected at different periods of time, and tested for the presence of specific antibodies and antigenic cross-reactivity. Results obtained show that children immunized with three doses of the Brazilian whole-cell pertussis vaccine present high levels of serum antibodies capable of recognizing the majority of the components present in vaccinal and non-vaccinal B. pertussis strains and their virulence factors for at least 2 years after the completion of the immunization procedure.

Pertussis seroprevalence in different age groups in Greece

In order to target the appropriate age population for booster vaccination, we examined the antibody titres against pertussis toxin (PT) in different age groups in immunized and non-immunized individuals. In the immunized population, the highest anti-PT levels were observed in the 0- to 2-y age group and the lowest in the teenager and young adult groups. In contrast, in the control group, anti-PT levels were minimal in infants and young children, increasing in adolescence and early adulthood, and waning after 30 y of age. Antibody levels >30 U/ml were observed with higher frequency in children <2 y of age, in individuals with complete vaccination history and in non-immunized individuals. These findings may have important implications in optimizing vaccination policies.

Seroprevalence of Immunoglobulin G antibodies against pertussis toxin among asymptomatic medical students in the west of Iran: a cross sectional study

Background

Pertussis is a highly communicable, vaccine-preventable respiratory infection. Immune response against this disease can be induced by infection or vaccination. Protection after childhood vaccination is minimal after ten years. Our aim was to assess pertussis immunity state in a population of healthy young medical students.

Methods

In this seroepidemiological survey, blood samples were obtained from 163 first-year medical students in Hamedan University, Iran. Serum level of IgG against pertussis toxin (IgG-PT) was measured by Enzyme-Linked Immunosorbent Assay (ELISA) method. For qualitative assessment, IgG-PT levels more than 24 unit (U)/ml were considered positive. Data was analysed qualitatively and quantitatively considering gender and age groups.

Results

There were 83 males and 80 females, with a mean age of 19.48 years, Prevalence of IgG-PT was 47.6% with mean level of 71.7 u/ml (95% confidence interval: 68.1–75.3). No statistically significant difference was observed with respect to sero-positivity of IgG-PT between males and females (45 cases (54%) vs. 34 cases (42%); P = 0.06). Mean IgG-PT levels in males and females were 84 U/ml and 58.8 U/ml, respectively (P = 0.91).

Conclusion

A considerable proportion of our study population with a positive history of childhood vaccination for pertussis was not serologically immune to pertussis. A booster dose of acellular pertussis vaccine may be indicated in Iranian, medical students regarding their serologic conditions and outstanding role in health care systems.

Booster vaccination of adults with reduced-antigen-content diphtheria, Tetanus and pertussis vaccine: immunogenicity 5 years post-vaccination

At 60 months post-vaccination, adults (mean age 45.6 years) randomised to receive combined reduced-antigen-content diphtheria-tetanus and acellular pertussis vaccine (dTpa) versus tetanus-diphtheria (Td)+monovalent acellular pertussis (pa) were seroprotected against diphtheria (> or =0.016IU/mL Vero cell assay) and tetanus (> or =0.1IU/mL ELISA assay) in 94.4% and 96.2%, respectively (dTpa), compared with 93.7% and 90.6% (Td+pa). Anti-FHA, anti-PT and anti-PRN antibodies (> or =5EL.U/mL) were maintained in 100%, 89.5% and 95.0% of dTpa versus 100%, 85.5% and 90.6% of pa vaccine recipients. At 5 years post boosting, antibody levels to diphtheria and tetanus are similar amongst adults receiving a dTpa or dT, and pertussis antibodies remain above pre-booster levels in at least 85%.

Assessment of humoral and cell-mediated immunity against Bordetella pertussis in adolescent, adult, and senior subjects in Italy

Humoral and cell-mediated immunity (CMI) against B. pertussis was assessed in a sample of adolescent, adult and senior subjects distributed in five different geographical areas in Italy. Most (99.1%) subjects had IgG anti-pertussis toxin (PT) antibodies exceeding the minimum detection level [> or = 2 ELISA units (EU)/ml]. There were no significant differences between the genders; 6.2% samples recorded titres > or = 100 EU/ml. CMI was positive [stimulation index (SI) > or = 5] against PT in 39.0% of all samples. This study suggests that B. pertussis continues to circulate in age groups that have been previously considered to be uninvolved in the circulation of this pathogen and that adolescent and adult pertussis boosters may be of value in these populations. Nevertheless, over the last 10 years, large increases in vaccination coverage rates have contributed to reduce the spread of the aetiological agent, especially in the immunized population.

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.

[Vaccination schedule of the Spanish Association of Pediatrics: recommendations 2007]

The Vaccine Advisory Committee of the Spanish Association of Pediatrics provides information on the new developments in vaccines that have taken place in 2006 and recommends certain modifications to the Immunization Schedule for 2007. To ensure early protection, the measles-mumps-rubella (MMR) vaccine booster dose should be administered when children start school (3-4 years). Based on existing scientific evidence, the importance of universal heptavalent conjugate pneumococcal vaccination, as occurs in most similar European countries and in the autonomous community of Madrid in Spain, is confirmed. The safety and efficacy of rotavirus and human papilloma virus vaccines, as well as their use in our environment, is discussed and the role of pediatricians in their implementation is stressed. The recommended immunization schedule for children and adolescents starting vaccination late is also discussed.

Whooping cough: are health-care workers putting children at risk?

AIM

To explore the attitudes and knowledge of health-care workers (HCW) towards whooping cough and an adult whooping cough booster for HCW.

METHODS

HCW at Fairfield Health Service, who had clinical contact with infants or children, were sent a self-administered questionnaire.

RESULTS

Questionnaires were completed by 135 staff, giving a response rate of 74%. Thirty-five per cent were not known to be immunised against whooping cough. Fifty-nine per cent of doctors were known to be immunised, 33% of allied health staff and 28% of nurses. The rates of immunisation between the professional groups were significantly different (chi2 = 8.2 with 2 degrees of freedom; P = 0.017). Thirty-nine per cent of HCW did not know that primary immunisation did not provide lifelong protection. Twenty-seven per cent did not agree that HCW should be offered an adult whooping cough booster. Staff who felt at risk of contracting whooping cough were more likely to recommend that a booster should be offered (OR 2.71; 95% CI 1.22-6.04; P = 0.019). Doctors were less likely to recommend that a booster should be offered (OR 0.36; 95% CI 0.15-0.87; P = 0.028).

CONCLUSIONS

HCW have low rates of immunity to whooping cough and misconceptions about whooping cough infection and immunisation. Over a quarter of HCW did not agree that a booster should be offered. An ongoing education programme addressing the attitudes and misconceptions identified in this study is a crucial component of the campaign to increase the uptake of adult whooping cough booster immunisation by HCW.

Knowledge, attitude, and practices with regard to adult pertussis vaccine booster in travelers

INTRODUCTION

Pertussis is a worldwide, highly communicable, vaccine-preventable respiratory disease and is a frequent but often underestimated cause of prolonged cough illness in adults. Immunity from childhood pertussis immunization is thought to last only up to 10 years. The incidence of adult pertussis has been estimated to be 200 to 500 per 100,000 persons-years. Acellular pertussis vaccines have been evaluated in adults and confer safe and effective protection and now exist as combination vaccine together with tetanus and diphtheria.

METHODS

We did a questionnaire survey to assess the knowledge, attitude, and practices toward pertussis in adult travelers. We consecutively enrolled all travelers who presented at the Travellers' Health & Vaccination Centre in Singapore in 1 month.

RESULTS

Of 218 consecutively enrolled travelers, 184 (84.4%) completed the questionnaire; of which 80% were Singaporeans. Seventy persons (38%) did not know or gave a wrong answer for the mode of transmission of pertussis, 147 (83%) had never heard of a pertussis vaccine for adults, and almost none had received an adult pertussis vaccine booster. Travelers from Western countries were seven times [95% confidence interval (CI): 2-27] more likely than Asians to have knowledge about pertussis; women were 4.27 times (95% CI: 1.59-11.53) more likely than men to be aware of the booster vaccine, after adjusting for nationality ( p= 0.004).

CONCLUSIONS

Knowledge about pertussis was poor among adult travelers. Although pertussis was viewed as a serious illness by the majority of participants, and 38% expressed the desire to be vaccinated, almost no one had received the pertussis vaccine booster. Awareness about pertussis, its risks, and prevention via vaccination need to be increased among adult travelers. Studies are needed to quantify the risk of pertussis in adult travelers.

Long-term humoral and cell-mediated immunity after acellular pertussis vaccination compares favourably with whole-cell vaccines 6 years after booster vaccination in the second year of life

Humoral and cell-mediated immune responses (CMI) were evaluated in subjects 3 and 6 years after primary and booster vaccination with either three-component acellular (Pa) or whole-cell (Pw) vaccines. Low anti-pertussis toxin (PT) antibody levels confirmed the absence of pertussis disease, consistent with ongoing protection. Anti-pertactin (PRN) antibodies, remained at higher levels in Pa-vaccinated subjects. At year 6, CMI responses continued to be present and were higher in Pa-vaccinated than Pw-vaccinated subjects. Long-term protection with Pa vaccines can be expected to be at least as good as that provided by efficacious Pw vaccines.

Community-acquired pneumonia: paving the way towards new vaccination concepts

Despite the availability of antimicrobial agents and vaccines, community-acquired pneumonia remains a serious problem. Severe forms tend to occur in very young children and among the elderly, since their immune competence is eroded by immaturity and immune senescence, respectively. The main etiologic agents differ according to patient age and geographic area. Streptococcus pneumoniae, Haemophilus influenzae, respiratory syncytial virus (RSV) and parainfluenza virus type 3 (PIV-3) are the most important pathogens in children, whereas influenza viruses are the leading cause of fatal pneumonia in the elderly. Effective vaccines are available against some of these organisms. However, there are still many agents against which vaccines are not available or the existent ones are suboptimal. To tackle this problem, empiric approaches are now being systematically replaced by rational vaccine design. This is facilitated by the growing knowledge in the fields of immunology, microbial pathogenesis and host response to infection, as well as by the availability of sophisticated strategies for antigen selection, potent immune modulators and efficient antigen delivery systems. Thus, a new generation of vaccines with improved safety and efficacy profiles compared to old and new agents is emerging. In this chapter, an overview is provided about currently available and new vaccination concepts.

Safety of reduced-antigen-content tetanus-diphtheria-acellular pertussis vaccine in adolescents as a sixth consecutive dose of acellular pertussis-containing vaccine

OBJECTIVE

The safety of a booster dose of a reduced-antigen-content tetanus-diphtheria-acellular pertussis (Tdap) vaccine was evaluated in adolescents previously vaccinated with five doses of acellular pertussis-containing vaccine.

STUDY DESIGN

Adolescents (n = 319) previously vaccinated with either 5 doses of diphtheria-tetanus-acellular pertussis (DTaP) (n = 193) or 4 doses of DTaP plus another acellular pertussis-containing vaccine received one dose each of Tdap and hepatitis A vaccine in a double-blinded, randomized, crossover trial. Rates of adverse events (AEs) after vaccination with Tdap versus hepatitis A and rates of local AEs among adolescents vaccinated with Tdap (sixth acellular pertussis-containing vaccine dose) versus rates in these same individuals after vaccination with their fifth DTaP dose were assessed.

RESULTS

After Tdap, pain (63.6%), redness (51.7%), and swelling (41.4%) were the most frequently reported AEs. Large injection site swelling (swelling > 100 mm, arm circumference increase > 50 mm or diffuse swelling interfering with daily activities) occurred in three adolescents and resolved without sequelae. After the sixth dose of acellular pertussis-containing vaccine, adolescents reported more pain and less redness and swelling compared with incidences of these AEs reported when these same individuals received their fifth DTaP dose.

CONCLUSIONS

These results suggest that Tdap is well tolerated as a sixth consecutive dose of acellular pertussis-containing vaccine.