An acellular pertussis vaccine in healthy adults: safety and immunogenicity. Pennridge Pediatric Associates

The effectiveness and safety of pertussis booster vaccination for adolescents and adults: A systematic review and meta-analysis

BACKGROUND

Due to the resurgence of pertussis, many countries have revised the pertussis immunization schedules and recommended booster doses of pertussis component vaccine for adolescents and adults. Here we aim to investigate the effectiveness and safety of pertussis component vaccines in adolescents and adults.

METHODS

Based on a prospectively registered protocol, we reviewed the literature and selected trials in adolescents and adults using pertussis component vaccine. We followed Cochrane and GRADE (Grading of Recommendations, Assessment, Development and Evaluation) guidance to assess risk of bias, quality of evidence and to perform meta-analyses.

RESULTS

A total of 17 clinical trials were included. At post-vaccination with pertussis component vaccine, the vaccine protective rate of pertussis reached 88.89%, the vaccine response rate of pertussis antibodies in most trials were above 85%, and the antibody titers at post-vaccination were higher than at pre-vaccination. Reduced-antigen-content diphtheria-tetanus-acellular pertussis vaccine was associated with significantly higher incidences of nausea [RR = 1.26, 95%CI:1.01, 1.57] and vomiting [RR = 2.08, 95%CI:1.21, 3.58] in acellular pertussis vaccines combined with tetanus and diphtheria (Tdap) group than diphtheria tetanus-toxoid vaccines (Td) group. Higher dose of diphtheria toxoid and adjuvant in dTap might cause higher incidence of fever.

CONCLUSIONS

Except for significant difference in gastrointestinal reaction (nausea, vomiting), acellular pertussis component vaccines are quite safe and has short-term effectiveness for the adolescents and adults. The adverse event of acellular pertussis component vaccine is similar to or safer than that of placebo or other vaccines without pertussis component.

Pertussis serology: assessment of IgG anti-PT ELISA for replacement of the CHO cell assay

Dalby T, Sørensen C, Petersen JW, Krogfelt KA. Pertussis serology: assessment of IgG anti-PT ELISA for replacement of the CHO cell assay. APMIS 2010; 118: 968–72.

Two types of serological assays are commonly used for the assessment of pertussis vaccine-induced antibodies; the Chinese hamster ovary cell (CHO cell) assay and the immunoglobulin G (IgG) anti pertussis toxin (PT) enzyme-linked immunosorbent assay (IgG anti-PT ELISA). Recently, both the techniques have been modified to improve performance with sera with interfering activity (CHO cell assay) or with heat-treated sera (IgG anti-PT ELISA). These two improved techniques were compared by the analysis of 100 individual serum samples from a previous clinical trial and 213 sera from a longitudinal serum collection from 20 Danish adults recently vaccinated with the Danish acellular pertussis vaccine. The comparison showed a significant linear correlation between the results of the two assays with a p-value of <0.0001 for the 100 individual samples. We, therefore, conclude that the improved IgG anti-PT ELISA can be used as a replacement for the often troublesome and time-consuming CHO cell assay for the measurement of vaccine-induced human antibodies to PT.

Administration of tetanus, diphtheria, and acellular pertussis vaccine to parents of high-risk infants in the neonatal intensive care unit

OBJECTIVE

Tetanus, diphtheria, and acellular pertussis vaccination is recommended for adults who are in contact with infants who are younger than 12 months and in the NICU. The objective of this study was to determine the feasibility of tetanus, diphtheria, and acellular pertussis vaccine administration to parents in a tertiary care, level III NICU and to measure its effect on vaccination rates among parents of this high-risk population.

METHODS

For a 4-month period from July to October 2007, all parents of admitted patients were informed of the risks and benefits of tetanus, diphtheria, and acellular pertussis vaccine by placing an information letter at their infant's bedside. All staff were educated about the dangers of pertussis infection and instructed to reinforce the need to obtain vaccination. Immunization was available for 20 hours per day at no cost. Student's t tests were used for data analysis.

RESULTS

During the study period, 352 children (598 eligible parents) were admitted to the NICU at gestational ages ranging from 23 to 42 weeks, and 495 (82.8%) parents were offered the vaccine. Overall vaccination rate was 86.9% (430 parents) of the screened population. Fifty-five (11.1%) parents in the screened cohort refused vaccination, predominately citing pertussis as an insignificant health threat or disbelief in vaccination. There were no differences in vaccination rate on the basis of parental age. No allergic reactions to vaccination were observed. The 54 infants whose parents were not offered vaccine had a significantly shorter length of stay, higher birth weight, and higher gestational age than parents who were offered vaccine.

CONCLUSIONS

Administration of tetanus, diphtheria, and acellular pertussis vaccine in the NICU is an effective means of increasing vaccination rates of parents of this population. Logistic barriers persist when implementing this program for infants with a short (<3-day) length of stay.

Tetanus-diphtheria-acellular pertussis vaccination of adults in the USA

Pertussis is an important cause of morbidity and mortality, and its incidence has been increasing in adolescents and adults over the past two decades. Waning immunity in adolescents and adults may be partially responsible. Adults can suffer significant illness from pertussis and its complications, such as pneumonia, rib fractures and syncope. Moreover, adults serve as a source of disease for infants, who are more vulnerable to severe complications and even death. The economic burden of pertussis is substantial, in terms of both medical and nonmedical costs. Fortunately, the burden of pertussis disease can now be safely and effectively reduced by vaccinating adults with tetanus-diphtheria-acellular pertussis (Tdap) vaccine. Further research is needed to elucidate the role of vaccination in pregnant women and those over 65 years of age, and also to determine whether further booster doses of Tdap are needed.

Acellular pertussis vaccines for adolescents

BACKGROUND

The epidemiology of pertussis is changing, with a clear increase in the number of cases diagnosed in adolescents and adults. This development has spurred studies and anticipated licensure of safer diphtheria, tetanus, acellular pertussis combined (Tdap) vaccines for this older population.

METHODS

Literature review.

RESULTS

Tdap vaccines are safe and immunogenic when administered to adolescents and adults. Correlates of immunity to pertussis after Tdap vaccination have not been established, but various combinations of antibody to pertussis antigens (pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae) provide protection. The importance of the number of antigens in Tdap vaccines for protection against mild pertussis disease is unclear. Pertussis vaccination establishes herd immunity after sufficient uptake within communities and countries. As experience with TdaP vaccines has accumulated, a 1-2% occurrence of large, local injection-site reactions with all TdaP vaccine products have been observed for booster doses in children 4-6 years of age. The frequency of large local reactions appears lower in adolescents and adults. The pathophysiologic mechanisms for the local reactions are not established, but a majority appears to be immunoglobulin E-mediated-reactive edema, and a minority appears to be immunoglobulin G-mediated Arthus-type reactions.

CONCLUSIONS

Tdap vaccines appear safe and immunogenic. The economic impact of pertussis provides a cost-benefit justification for widespread use of Tdap vaccine boosting in adolescents.

Economic considerations for pertussis booster vaccination in adolescents

BACKGROUND

Despite good acellular pertussis vaccine safety and protective efficacy, as well as high vaccination rates among young children, the incidence of pertussis in the United States has steadily increased since the 1980s. This is especially true for adolescents and adults who are susceptible because of waning immunity, which is not long lived. Other populations are at increased risk for morbidity of infection, although infants younger than 6 months of age who have not completed the primary immunization series have the greatest morbidity and mortality. Other groups who might benefit from booster immunizations include hospital workers, family contacts, and individuals with compromised health. Although older individuals generally have milder illnesses, they are often the source of infection for younger children. An adolescent/adult formulation of acellular pertussis vaccine requires a lower dose of pertussis antigens and can be combined with currently recommended diphtheria and tetanus toxoids (Tdap). These new vaccines for adolescents and adults are safe, immunogenic, and protective.

METHODS

Through an extensive review of the literature, the direct and indirect costs associated with pertussis and its complications are examined, cost-benefit analyses of pertussis booster vaccination are evaluated for different groups, and the economic considerations involved in implementing a pertussis booster vaccination program in adolescents are discussed.

RESULTS

Pertussis infections cause outbreaks in schools, families, and workplaces, resulting in prolonged morbidity and significant costs for medical care, lost time, and wages. Physician visits, chest radiographs, and antibiotics comprise the majority of direct costs, and costs associated with work loss often comprise the majority of indirect costs related to pertussis illness. Adolescents and adults also transmit their infections to nonimmune children. A cost-benefit analysis evaluated the health and economic benefits of seven strategies for administering a pertussis booster. The most economical strategy is to immunize all adolescents 10-19 years of age, which may prevent 0.4-1.8 million cases of pertussis and save US 0.3-1.6 billion dollars in a decade. A tetanus and diphtheria booster (Td) is currently recommended for children 11-12 years of age. The Tdap vaccine offers an enhancement for the Td booster by providing protection against pertussis, and it will not require an additional injection or office visit.

CONCLUSIONS

Immunizing adolescents with a pertussis booster in the form of Tdap is the most economical and easiest-to-implement strategy and should provide significant health and economic benefits.

Potential strategies to reduce the burden of pertussis

Pertussis continues to be a significant cause of morbidity and mortality among nonimmunized young infants. Although the inception of childhood pertussis immunization programs has significantly reduced the occurrence of the disease in children, waning vaccine-induced immunity permits the disease to affect adolescents and adults, who in turn transmit the disease to unimmunized or incompletely immunized infants. The Global Pertussis Initiative brought together experts from 17 countries around the world to evaluate strategies to improve disease control. Seven strategies were considered: (1) universal adult immunization; (2) selective immunization of mothers and close family contacts of newborns; (3) selective immunization of health care workers; (4) selective immunization of child care workers; (5) universal immunization of adolescents; (6) preschool booster at 4-6 years of age; and (7) reinforcement and/or improvement of current infant and toddler immunization strategies. Because immunization programs vary widely from country to country, no single strategy is likely to be appropriate for all. Moreover it would be helpful to have additional data to support the strategies and provide a better understanding of the disease so that new approaches can be monitored effectively. However, certain steps can be taken now to reduce the incidence of pertussis.

Immunogenicity and reactogenicity of combined acellular pertussis/tetanus/low dose diphtheria vaccines given as a booster to UK teenagers

Sustained high incidence of pertussis, particularly amongst unvaccinated infants, is of concern. Inclusion of pertussis vaccination with tetanus and low dose diphtheria (Td) teenage boosters may protect individuals through reproductive years, and prevent transmission to offspring. UK teenagers who had previously received only a three-dose primary course of whole cell pertussis vaccination in infancy and who were due to receive a Td booster (n=323) were randomised to four groups: Td, TdaP, TdaP-inactivated polio vaccine (IPV) (Aventis Pasteur), TdaP (GlaxoSmithKline). There were significant pre- to post-vaccination GMC and GMFR increase for vaccine-contained pertussis antigens (p<0.001) in recipients of aP-containing vaccine. All groups demonstrated significant increases pre- to 4 weeks post-vaccination in diphtheria (D)/tetanus (T) geometric mean concentrations (GMCs) and fold rises (GMFRs) (p<0.001). Groups all achieved similar D and T post-vaccination GMCs. Local reactogenicity was generally similar between groups and was not associated with pre-booster diphtheria/tetanus antibody levels. A minority of vaccinees reported systemic symptoms with similar proportions between groups for each symptom assessed. This study demonstrated that addition of aP and/or IPV to Td vaccine did not materially alter reactogenicity or immunogenicity of Td components, and induced immune responses to pertussis antigens in teenagers who had received no pertussis vaccine since infancy.

Acellular Pertussis Vaccine Safety and Efficacy in Children, Adolescents and Adults

This review offers a perspective on the acellular pertussis vaccine efficiency trials concluded in the 1990s and presents the main conclusions of a meta-analysis of 52 studies that assessed the safety and efficacy of the diphtheria-tetanus (DT)-whole cell pertussis (DTwP) and DT-acellular pertussis (DTaP) vaccines administered to children. A clear serological correlate of immunity to pertussis following DTaP vaccination was not identified despite an intensive analysis. It can be speculated that this may be because various combinations of antibody to agglutinogens (pertussis toxin, filamentous haemagglutinin, pertactin and fimbriae) provide protection, or because serum antibody levels and responses do not uniformly reflect mucosal IgA antibody levels.Long-term efficacy following DTaP vaccination is becoming characterised and cell-mediated immunity (T-cell memory) may have importance. DTaP vaccination appears to establish herd immunity after sufficient uptake within communities and countries. As experience with DTaP vaccine safety has accumulated, a 1-2% occurrence of large, local injection reactions with all products has been defined for booster doses. The pathophysiological mechanisms for the reactions are not established but a majority appear likely to be IgE-mediated reactive oedema and a minority to be IgG-mediated reactive Arthus-type reactions. DTwP and DTaP combinations with other vaccines have been studied and licensed; the most controversial combination products are the DTaP/Haemophilus influenzae type B polysaccharide conjugate vaccines. Pertussis epidemiology is changing with a clear increase in occurrence in adolescents and adults. This development has spurred studies and licensure of safer DTaP vaccines for this older population. The economic impact of pertussis and transmission from adults to vulnerable infants provides a cost-benefit justification for widespread use of DTaP vaccines in all age groups with routine boosting every 10 years.

Serologic response and antibody-titer decay in adults with pertussis

Pertussis is a frequent and significant illness in adults. Because acellular pertussis vaccines for use in adolescents and adults have now been developed, it is important to compare serologic responses in adults after infection with serologic responses in adults after vaccination. We measured IgG and IgA antibodies to 4 Bordetella pertussis antigens at approximately 6-month intervals for 28 months in 11 adults with pertussis. After reaching peak levels, titers of antibody to pertussis toxin decreased more than did titers of antibodies to filamentous hemagglutinin, pertactin, and fimbriae type 1 and type 2. Although studies of adults who have been vaccinated with acellular pertussis vaccines have had shorter follow-up periods than studies of adults with pertussis infection, the antibody decay patterns are similar in both groups.

Molecular typing of Bordetella pertussis isolates recovered from Belgian children and their household members

Recently, a moderate increase in the prevalence of pertussis, possibly contracted from adults, has been observed among unvaccinated children. During a 3-year period, we prospectively enrolled 93 index patients with a polymerase chain reaction (PCR) and/or culture result positive for Bordetella pertussis. Among 63 household contacts of 28 index patients, PCR and culture for B. pertussis identified 25 B. pertussis-positive persons. Nineteen of 25 B. pertussis-positive household contacts were asymptomatic. Isolates were available from 10 families of both index patients and household contacts for molecular typing by pulsed-field gel electrophoresis (PFGE) and for genotyping of pertactin and pertussis toxin by sequence-specific PCR and sequencing. PFGE demonstrated homogeneity among the isolates recovered from within each family but heterogeneity among the isolates recovered from different families. B. pertussis isolates recovered from index patients and their household contacts were indistinguishable by molecular typing, demonstrating that identical strains can cause full pertussis disease in children and asymptomatic infection in adults and adolescents.

Pertussis of adults and infants

Bordetella pertussis continues to circulate even in populations where a high vaccine coverage of infants and children is achieved. Cases in adolescents and adults are reported with increasing frequency in many countries. Adults are a reservoir for infections in very young infants, in whom pertussis may be severe and life-threatening. The salient clinical feature of pertussis in adolescents and adults is prolonged coughing, and recognising that pertussis does occur in these age groups is the most important step in its diagnosis. A laboratory diagnosis can be made by bordetella-PCR from nasopharyngeal swabs or secretions and by detection of antibodies, mainly to pertussis toxin; laboratory diagnosis is, however, not well standardised. Vaccination of adolescents and adults is now possible with acellular pertussis vaccines, which are well tolerated, immunogenic, and effective. Adolescent boosters and the vaccination of health-care workers are already included in vaccination calendars in some countries. Vaccine-recommending bodies and national health-care organisations must have locally relevant information on the transmission of pertussis from adults to infants to be able to make decisions on the advisability, feasibility, and priority for booster immunisation against pertussis.

Waning immunity and sub-clinical infection in an epidemic model: implications for pertussis in The Netherlands

In The Netherlands, an epidemic outbreak of pertussis took place in 1996-1997. Understanding of the causes of the epidemic is hampered by the fact that many cases of infection with Bordetella pertussis go by unnoticed, and by the fact that immunity against infection does not last lifelong. Motivated by these observations, we develop and analyze an age-structured epidemic model that takes these factors into account. A distinction is made between infection in immunologically naive individuals, and infection in individuals whose immune system has been primed before by infection or vaccination. While the former often lead to severe symptoms and thus are more often diagnosed and notified, the latter are largely sub-clinical. The main questions are: (1) to what extent do sub-clinical infections contribute to the circulation of B. pertussis; and (2) what might be the causes for the recent epidemic? To answer these questions, we first present a new method to estimate the force of infection from notification data. The method is applied to the 1988-1995 case notification data from The Netherlands. Estimates of the force of infection vary greatly, depending on the rate at which immunity is lost, and on the fraction of sub-clinical infections. For the 1988-1995 period, our analysis indicates that if immunity is lost at a small rate and if a majority of infections is sub-clinical, the contribution of infection in adults to the transmission process cannot be neglected. Our results furthermore indicate that a decrease in the duration of protection after vaccination due to a change in the pathogen is the most likely factor to account for the 1996-1997 epidemic.