Economic considerations for pertussis booster vaccination in adolescents

Childhood pertussis is still here: An Asian city's perspectives

INTRODUCTION

Pertussis, or whooping cough, is a highly contagious respiratory infection that is caused by the bacterium Bordetella pertussis. It is one of the most common causes of death in childhood. It is also a frequent cause of chronic cough in children, adolescents, and adults.

METHODS

Global and Hong Kong perspectives of childhood pertussis were described.

RESULTS

Hong Kong has prided herself in the city's childhood immunization program. There appear to be no major outbreaks of pertussis since the 1960s. Nevertheless, pediatricians may see isolated cases of pertussis or pertussis-like cases from time to time. Occasionally, infants are severely affected with apneas and managed with ventilator supports in the PICU. Outbreaks of the notifiable disease continue to occur despite a reasonable surveillance system and vaccination program in Hong Kong. Vaccination of mothers, adolescents, and adults are efficacious methods to further reduce the risks of pertussis. Macrolides remain efficacious antibiotics especially used early during the infectious phase. Infants with pertussis may require intensive care support and morbidity is high.

CONCLUSIONS

Physicians should be reminded from time to time that outbreaks of pertussis still exist in Hong Kong and in many cities globally.

Prevalence of B. pertussis infection in children with clinically suspected pertussis

BACKGROUND

Pertussis is an important cause of hospitalization in children. Limited data on pertussis have been reported from China. The aim of this study was to characterize clinically suspected pertussis attributable to Bordetella pertussis among children and determine factors associated with longer duration of hospital stay in B. pertussis infection.

METHODS

Two hundred and seventeen consecutive children with clinically suspected pertussis were prospectively enrolled in the study between Jan 2016 through Aug 2017. Variables assessed included demographics, clinical symptoms and laboratory findings. Cox proportional hazards regression model were used to predict variables associated with longer duration of hospital stay.

RESULTS

Among the 217 patients with clinically suspected pertussis, B. pertussis was found in 106 (48.8%) patients. Of the 106 children with B. pertussis infection, 63 (59.4%) patients had coinfections with majority due to rhinovirus (HRV) (30.2%), Mycoplasma pneumoniae (29.2%) and human bocavirus (hBoV) (11.3%). Presence of coinfection [odds ratio (OR): 1.73, CI: 1.17-2.54], age ≤ 3 months (OR: 1.51, CI: 1.09 to 2.27), and WBC count ≥30 × 10⁹/L (OR: 1.66, CI: 1.07 to 2.84) were independently associated with a longer hospital stay.

CONCLUSIONS

B. pertussis infection had a high coinfection rate with the majority of coinfections due to HRV, M. pneumoniae and hBoV. Presence of coinfection, Age ≤3 months and WBC count ≥30 × 10⁹/L were associated with a longer hospital stay. Children admitted with pertussis need close monitoring when they had evidence of coinfection, Age ≤3 months, WBC count ≥30 × 10⁹/L.

A sera-epidemiological study on pertussis immunity levels among community populations and an analysis of the underlying factors in Tianjin China

BACKGROUND

The aim of this study is to characterize the sera-epidemiology of pertussis immunity levels among community populations and to identify the underlying factors. Moreover, our study will help resolve new issues encountered during the control and prevention of pertussis reemergence.

METHODS

The anti-pertussis antibody levels among community populations were examined using enzyme linked immunosorbent assays (ELISA) over three years. Comparative studies were carried out to assess the efficacy of different types of vaccines. Meanwhile, the duration of protection provided by DTaP within the under-7 age group was subjected to further analysis.

RESULTS

The average positive rate for anti-pertussis antibody was 49.15% across all community populations, among which the 4-12 age group showed a rate substantially lower than those of other groups (P<0.001). There was no statistically significant difference in anti-pertussis antibody levels (P=0.977) between people receiving three and four doses of the vaccine. The surveillance results showed that the positive antibody response rate elicited by component pertussis combo (DTcP) vaccines (84.44%) was strikingly higher than that elicited by acellular pertussis combo (DTaP) vaccines (37.22%, P<0.001). More specifically, when given 4 doses of DTcP vaccines, 66.67% of the people showed positive anti-pertussis toxin (PT) antibody levels, which was higher than the ratio of 9.87% (P<0.001) in the case of DTaP vaccines. The positive anti-pertussis antibody levels peaked at 73% within the first five months following vaccination and then gradually decreased to below 20% in four years. The positive rate was inversely correlated with the length of time after vaccination (r=-0.929, P=0.003).

CONCLUSIONS

The anti-pertussis antibody levels were not only relatively low among community populations, but also dropped excessively rapidly among vaccinated populations. Natural infection is an important contributor to the high pertussis immunity levels seen in adolescents and adults. The efficacy of DTaP remains to be improved.

Increasing incidence of pertussis in Brazil: a retrospective study using surveillance data

BACKGROUND

Many countries have reported an increase in the incidence of pertussis, which has become a global public health concern.

METHODS

In this study, the epidemiology of pertussis in Brazil was assessed retrospectively using surveillance data gathered from case notification forms from 2007 to 2014.

RESULTS

From 2007 to 2014, 80,068 suspected cases of pertussis were reported in Brazil. Of these, 24,612 (32 %) were confirmed by various criteria. The annual distribution of confirmed cases demonstrated a significant increase in incidence rate since 2012. A seasonal pattern in which cases occur most frequently between the end of spring and midsummer has been identified. Among the confirmed cases, 34.5 % occurred in infants aged 0-2 months, 22.4 % occurred in infants aged 3-6 months, 21 % occurred in children aged 7 months to 4 years, and 8 % were reported in adults >21 years. Of the confirmed cases, 47.2 % met only clinical criteria, 15.5 % met clinical and epidemiological criteria, and 36.6 % were confirmed in a laboratory. The overall case fatality rate was 2.1 %, reaching 4.7 % among infants aged 0-2 months. The complications most commonly reported in the notification forms were pneumonia, encephalitis, dehydration, otitis, and malnutrition. Of the confirmed cases, 23.1 % occurred in subjects who received at least 3 doses of the pertussis vaccine. Within this group, there were 1098 infants aged 7 to 15 months and 2079 children aged 16 months to 4 years. In 2012, 18 states did not achieve 95 % immunization coverage, a number that dropped to 10 and 6 in 2013 and 2014, respectively.

CONCLUSIONS

Brazil's main challenges in facing pertussis resurgence will be to offer the best quality medical attention to reduce mortality, to improve the infrastructure for laboratory diagnosis and to increase vaccination coverage. Additional studies to assess the effectiveness of the current vaccination schedule and basic research on the genetics and evolution of circulating B. pertussis strains are also needed.

Impact of tetanus, diphtheria, and acellular pertussis (Tdap) vaccine use in wound management on health care costs and pertussis cases

BACKGROUND

The Advisory Committee on Immunization Practices (ACIP) recommends the use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine for routine wound management in adolescents and adults who require a tetanus toxoid-containing vaccine who were vaccinated ≥ 5 years earlier with tetanus toxoid, reduced diphtheria toxoid (Td) vaccine, and who have not previously received Tdap.

OBJECTIVE

To estimate the overall budget and health impact of vaccinating individuals presenting for wound management with Tdap instead of Td vaccine, the current standard of care in practices that do not use Tdap for purposes of wound management.

METHODS

A decision-analytic economic model was developed to estimate the expected increase in direct medical costs and the expected number of cases of pertussis avoided associated with the use of Tdap instead of Td vaccine in the wound management setting. Patients eligible for Tdap were aged 10+ years and required a tetanus-containing vaccine. Age-specific wound incidence data and Td and Tdap vaccination rates were taken from the National Health Interview Survey and the National Immunization Survey for the most recent available year. Age-specific pertussis incidence used in this analysis (151 per 100,000 for adolescents, 366 per 100,000 for those aged 20-64 years, and 176 per 100,000 for those aged 65+ years) used reported incidence rates adjusted by a factor of 10 for adolescents and by a factor of 100 for adults, based on assumptions previously made by ACIP to account for underreporting. Vaccine wholesale acquisition costs without federal excise tax were assumed in the base case. Efficacy of vaccination with Tdap in preventing pertussis was based on clinical trial data. Possible herd immunity effects of vaccination were not included in the model. Costs associated with vaccination and treatment of pertussis cases were reported as total annual costs and per-member-per-month (PMPM) costs for hypothetical health plans and for the U.S. population. Aggregate and incremental costs and pertussis cases avoided were presented undiscounted (as recommended for budget-impact analyses) annually and cumulatively over a 3-year time horizon in 2012 U.S. dollars. Scenario analyses were conducted on key parameters, including wound incidence, pertussis incidence, vaccine efficacy and waning protection against pertussis, uptake rates for Tdap, and vaccine prices using alternative data sources or alternative clinically relevant assumptions.

RESULTS

For a health plan with 1 million covered lives aged < 65 years, vaccination with Tdap instead of Td was estimated to cost an additional $132,364 ($0.01 PMPM) in the first year and an additional $368,640 ($0.01 PMPM) cumulatively over 3 years. For a health plan with 1 million covered lives aged 65+ years, vaccination with Tdap instead of Td was estimated to cost an additional $201,165 ($0.02 PMPM) in the first year and an additional $549,568 ($0.02 PMPM) cumulatively over 3 years. For the U.S. population aged 10+ years, vaccination with Tdap instead of Td was estimated to result in protection against pertussis for an additional 2.7 million patients with wounds annually and was estimated to cost an additional $121,101,671 to avoid 42,104 cases of pertussis over the 3-year time horizon. Results were sensitive to input parameter values, particularly parameters associated with the number of patients with wounds vaccinated with Tdap (range 2.7 to 5.1 million patients). However, for all of the alternative scenarios tested, the expected increase in PMPM costs ranged from < $0.01 to $0.03.

CONCLUSIONS

Vaccination of adolescents and adults with Tdap for wound management may result in an increase in PMPM costs for health plans of < $0.01 to $0.03. Given the potential reduction in pertussis cases at the population level, vaccination with Tdap for routine wound management could be considered as another strategy to help address the pertussis public health concern in the United States.

Whooping cough in 2014 and beyond: an update and review

Pertussis, or whooping cough, has had a dramatic resurgence in the past several years and is the most common vaccine-preventable disease in the world. The year 2012 marked the most cases in the United States in &gt; 50 years. Large outbreaks have occurred in multiple states, and infant deaths have drawn the attention of not only health-care providers but also the media. Although the disease is theoretically preventable by vaccination, it remains a challenge to control. New vaccination strategies have been implemented across different age groups and populations of patients, but vaccine coverage remains dismally low. Acellular vaccines, although safe, do not afford the same long-lasting immunity as the previously used whole-cell vaccine. Ultimately, improvements in the development of vaccines and in vaccination coverage will be essential to decrease the burden of pertussis on society. This article provides a review of pertussis infection and discusses advances related to the epidemiology, diagnosis, treatment, and prevention of infection, as well as continued areas of uncertainty.

Infectious diseases and vaccination strategies: how to protect the "unprotectable"?

Introduction. The circulation of infectious diseases puts small infants too young to be vaccinated at risk of morbidity and mortality, often requiring prolonged hospitalization. Material and Methods. We have reviewed the medical records of children not eligible for vaccination because of age, admitted to hospital for pertussis, measles, or varicella from February 1, 2010, till February 1, 2012. Results. Of the case records scrutinized, 21 were hospitalized for pertussis, 18 for measles, and 32 for varicella. Out of them, 42%, 66%, and 78% diagnosed with, respectively, pertussis, measles, and varicella had a complicated course of the disease. Discussion. To avoid infectious disease circulation, childhood immunization strategies should be adopted, such as vaccination of healthcare givers, adult household contacts, and parents planning to have, or who have had, a newborn baby.

Tdap5 vaccine (Covaxis): a review of its use as a single-booster immunization for the prevention of tetanus, diphtheria, and pertussis in children (aged 4 years), adolescents, and adults

Covaxis (also licensed as Triaxis or Adacel in individual countries) is a combined tetanus toxoid, reduced diphtheria toxoid, five component acellular pertussis (namely detoxified pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae types 2 and 3) vaccine for the prevention of diphtheria, tetanus, and pertussis. It is approved for use in Europe as a single intramuscular booster dose in children (aged ≥ 4 years), adolescents, and adults, and in the US it is approved for use in individuals aged 11-64 years. In large, randomized, controlled clinical trials conducted in the UK and North America, a single intramuscular booster dose of Covaxis induced robust immune responses for all of its component antigens when given to children (aged ≥ 4 years), adolescents, and adults. In addition, Covaxis vaccine was safe and generally well tolerated in terms of solicited and unsolicited local injection-site and systemic adverse events, most of which were of mild intensity and resolved without sequelae. Furthermore, the immunogenicity of each individual component and the reactogenicity of Covaxis vaccine in children, adolescents, and adults was generally similar to that of comparator vaccines. Despite being a vaccine-preventable disease and having >90% primary vaccination coverage worldwide, pertussis remains uncontrolled, particularly amongst adolescents and adults. Given the changing epidemiology of pertussis and the requirement to reduce infection in adolescents and adults (including healthcare workers) and thereby prevent transmission of the disease from these individuals to very young infants, the new 'cocoon strategy' recommended in current vaccination guidelines has become a key strategy in the management of morbidity and mortality associated with pertussis. This strategy focuses on the immunization of healthcare workers, and the parents and family members of infants who are too young to have undergone primary immunization, so as to prevent the transmission of pertussis to these young at-risk infants. The implementation of the 'cocoon strategy' may finally give countries the ability to control pertussis infections in these at-risk infants and ultimately provide the desired herd immunity against pertussis. In line with this strategy, a booster dose of Covaxis vaccine provides a valuable option to reduce pertussis morbidity and mortality, and to maintain seroprotection against diphtheria and tetanus in children (aged ≥ 4 years), adolescents, and adults.

Cost-effectiveness analysis of various pertussis vaccination strategies primarily aimed at protecting infants in the Netherlands

BACKGROUND

Pertussis is a highly contagious respiratory disease. Despite a high rate of vaccine coverage through the Dutch national immunization program, the incidence of pertussis remains high in the Netherlands and the risk of infection continues. Because pertussis is most severe in unimmunized infants and infants who have only received some of the recommended doses, new pertussis immunization strategies should be considered to protect this vulnerable population.

OBJECTIVE

This study was designed to estimate the cost-effectiveness of 3 new immunization strategies for possible addition to the current Dutch national immunization program: immunization of the infant at birth, immunization of the parents immediately after birth of the child (cocooning), and maternal immunization during the third trimester of pregnancy.

METHODS

A literature search was performed in the PubMed database for articles published in English, German, and Dutch using the following terms: pertussis, whooping cough, vaccination strategies, maternal immunization, cocooning, at birth, vaccine efficacy, mortality, underreporting, prevalence, incidence, and cost-effectiveness. A decision-tree model was developed for this analysis, and data on pertussis morbidity and costs were collected consistently for different age groups (infants <1 year of age and adults 25 to 34 years of age). The size of the infant cohort was set at 200,000 to approximate previous Dutch birth cohorts. The size of the adult cohort was set at 401,380 parents for the cocooning strategy and 201,380 mothers for the maternal immunization strategy. Health benefits (quality-adjusted life-years [QALYs]) and costs were estimated in both cohorts for each of the 3 immunization strate- gies. Incremental cost-effectiveness ratios were calculated from both a payer's and a societal perspective. The robustness of the results was determined through sensitivity analysis.

RESULTS

In the base-case analysis, cocooning and maternal immunization were found to be effective in reducing the incidence of pertussis among infants (123 and 174 infant cases were expected to be prevented, respectively). Furthermore, cocooning and maternal immunization were estimated to be cost-effective from a payer's perspective (euro4600 [US $6400]/QALY and euro3500 [$4900]/QALY, respectively) and even cost-saving from a societal perspective (savings of up to euro7200 [$10,100] and euro5000 [$7000], respectively). Sensitivity analyses revealed that favorable cost-effectiveness was generally robust. In the sensitivity analysis, the cost-effectiveness of cocooning and maternal immunization was mostly sensitive for changes in assumptions on underreporting (200-fold increase in reported number of symptomatic cases) of pertussis disease and infection. With no underreporting, the ICER was estimated at euro211,900 ($296,700)/QALY for cocooning and euro81,600 ($114,200)/QALY for maternal immunization from a payer's perspective. However, even at much lower levels of underreporting (20- to 30-fold increase in incidence), cost-effectiveness remained favorable. The cost-effectiveness of the third strategy, at-birth immunization, was highly unfavorable (euro329,900 [$461,900]/QALY from a payer's perspective and euro330,100 [$462,100]/ QALY from a societal perspective).

CONCLUSIONS

This study estimated that the addition of cocooning or maternal immunization to the current Dutch national immunization program likely would be cost-effective or even cost-saving. These estimates were mainly due to reduction in the number of cases among parents, which are likely to be mild and therefore would largely remain unreported. Immunization at birth was not a cost-effective strategy. Cocooning was the most expensive intervention to implement; however, it resulted in the highest number of QALYs gained (mainly in adults). Maternal immunization would offer better protection of infants, due to maternally acquired antibodies.

Boostrix: a reduced-dose acellular pertussis vaccine for use in adolescents and adults

Pertussis remains a serious problem in many countries. Even in countries with high vaccine coverage and a long vaccination history, pertussis outbreaks occur periodically. Rather than being a disease of young children, pertussis has shifted to affect adolescents and adults. Increased pertussis burden in adolescents and adults is the major source of severe infection for young infants. An effective vaccine is needed to control the spread of pertussis beyond preschool children. Boostrix is a reduced-dose acellular pertussis vaccine with diphtheria and tetanus toxoids, and is designed for use in adolescents and adults. Current evidence suggests that Boostrix is immunogenic and well tolerated. The pertussis component of Boostrix has been shown to be efficacious in a large-scale Phase III trial. More than 50 countries have given permit to the use of Boostrix, and many of them formally recommend the use of Boostrix in adolescents and adults. Designed as a vaccine for adolescence and adults, Boostrix has a long way to go to achieve large-scale use in those target groups. Nevertheless, we expect that the advent of Boostrix will lead to a much better control of pertussis in the general population.

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.

Current issues in adolescent immunization

Based on the December 2006 Fondation Mérieux International Scientific Symposium, the current state of adolescent immunization is reviewed with a focus on the policy and programmatic issues that impact the acceptability, initiation, and successful implementation. Key questions are identified with proposed strategies to help achieve successful adolescent immunization programs. The role of current vaccines targeted to adolescents, such as those directed against invasive meningitis, pertussis, and the human papillomavirus, is reviewed as well as their role in rejuvenating interest in adolescent immunization, and more importantly, adolescent health as a whole.

Pertussis in adolescents

Pertussis is a highly communicable respiratory infection caused by Bordetella pertussis. In spite of the widespread availability of effective vaccines and high levels of vaccination coverage, a significant resurgence in pertussis has been observed during the past 2 decades. The increase in reported cases is due in large part to infection in adolescents and adults, and waning immunity plays an important role. Pertussis in adolescents and adults often goes unrecognized because a persistent, uncharacteristic cough might be the only clinical presentation. Pneumonia is the most frequent complication. Culture and polymerase chain reaction are helpful in establishing the diagnosis if a specimen can be obtained early in the course of the illness. Serology is useful when the diagnosis is not suspected until a later stage. Treatment with a macrolide antibiotic is recommended for affected individuals, as well as for all household and other close contacts. Universal immunization is necessary for disease control. Immunization should begin in infancy and should continue with booster doses through adulthood. Two adolescent and adult formulations of acellular pertussis vaccine are licensed in North America and Europe. Both are combined with an adult formulation of diphtheria and tetanus toxoids. In the US, Adacel (Sanofi Pasteur, Toronto, Ontario, Canada) is licensed for use in individuals aged 11 to 64 y while Boostrix (GlaxoSmithKline Biologicals, Rixensart, Belgium) is licensed for use in individuals aged 10 to 18 y. These vaccines are safe, immunogenic, and well tolerated. Routine vaccination of adolescents and adults is required for optimal control of pertussis.

Adolescent immunizations: a position paper of the Society for Adolescent Medicine

New vaccines are being targeted to help protect the adolescent population from disease. The Society for Adolescent Medicine strongly urges compliance with adolescent vaccination recommendations provided by the Advisory Committee on Immunization Practices. These vaccines will significantly impact the health and well-being of the adolescent population. To enhance vaccination compliance and access to prevention health care and promotion, the Society supports linking vaccination to the three distinct comprehensive preventive health care visits already recommended by multiple organizations during early, middle, and late adolescence. In addition, multiple provider strategies should be used to increase vaccination rates among adolescents.

Prevention of pertussis among adolescents: recommendations for use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine

The purpose of this statement is to provide the rationale and recommendations for adolescent use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines. Despite universal immunization of children with multiple doses of pediatric diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccine, pertussis remains endemic with a steady increase in the number of reported cases. Two peaks in the incidence of pertussis occur in pediatric patients: infants younger than 6 months of age who are inadequately protected by the current immunization schedule and adolescents 11 through 18 years of age whose vaccine-induced immunity has waned. Significant medical and public health resources are being consumed in postexposure management of adolescent cases, contacts, and outbreaks with little beneficial effect on individuals or the epidemiology of disease. Two Tdap products were licensed in 2005 for use in people 10 through 18 years of age (Boostrix) and 11 through 64 years of age (Adacel). The American Academy of Pediatrics recommends the following: 1. Adolescents 11 to 18 years of age should receive a single dose of Tdap instead of tetanus and diphtheria toxoids (Td) vaccine for booster immunization. The preferred age for Tdap immunization is 11 to 12 years. 2. Adolescents 11 to 18 years of age who have received Td but not Tdap are encouraged to receive a single dose of Tdap. An interval of at least 5 years between Td and Tdap is suggested to reduce the risk of local and systemic reactions; however, intervals of less than 5 years can be used, particularly in settings of increased risk of acquiring pertussis, having complicated disease, or transmitting infection to vulnerable contacts. Data support acceptable safety with an interval as short as approximately 2 years. 3. Tdap and tetravalent meningococcal conjugate vaccine (MCV4 [Menactra]) should be administered during the same visit if both vaccines are indicated. If this is not feasible, MCV4 and Tdap can be administered using either sequence. When not administered simultaneously, the American Academy of Pediatrics suggests a minimum interval of 1 month between vaccines. The rationale for this strategy is to provide direct protection of immunized adolescents. With implementation of vaccine recommendations, indirect benefitalso is likely to extend to unimmunized peers and other age groups. The strategy of universal Tdap immunization at 11 to 12 years of age is cost-effective.