The induction of breast milk pertussis specific antibodies following gestational tetanus–diphtheria–acellular pertussis vaccination

Background

Center for Disease Control and Prevention recommends vaccination of pregnant women with tetanus–diphtheria–acellular pertussis (Tdap).

Aim

To measure pertussis specific antibodies, total protein and their ratio in breast milk following gestational Tdap vaccination.

Methods

Women who received Tdap after the 20th week of pregnancy were recruited and unvaccinated women served as controls. Breast milk total protein, immunoglobulin A (IgA) to pertussis toxin (PT), filamentous hemagglutinin (FHA) and immunoglobulin G (IgG) to PT, FHA and pertactin (PRN) were measured. To overcome the dilution that occurs in the transition from colostrum to mature breast milk, we calculated pertussis specific antibody to total protein ratio.

Results

Pertussis specific IgA was the predominant pertussis immunoglobulin in the colostrum of Tdap vaccinated women with the geometric mean concentrations (GMCs) of IgA to FHA higher than for IgA to PT, 24.12 ELISA units/milliliter (EU/mL) vs. 8.18 EU/mL, respectively, p < 0.004. There were differences between the vaccinated women and controls in the GMCs of IgA to FHA and IgG to PRN in the colostrum, 24.12 EU/mL vs. 6.52 EU/mL, p = 0.01 and 2.46 EU/mL vs. <0.6 EU/mL, p = 0.03, respectively. The GMCs of total protein showed significant decline over 8 weeks in the vaccinated women and controls, p < 0.004. Among vaccinated women, there was significant decline in the GMCs of IgA to PT and FHA over 8 weeks, p < 0.001. The geometric mean ratio of IgA to FHA to total protein also declined significantly over 8 weeks in the vaccinated women, p < 0.01, demonstrating a true decrease, however, pertussis IgA was measurable at 8 weeks.

Conclusions

Select colostrum pertussis antibody levels were significantly higher among women vaccinated with Tdap during pregnancy compared with unvaccinated women. Among vaccinated women, maximal levels of pertussis specific IgA were in the colostrum but still detected at 8 weeks. Lactation may augment infant's protection against pertussis.     

Booster vaccination of toddlers with reduced antigen content diphtheria–tetanus–acellular pertussis vaccine

Immunogenicity and reactogenicity of DTPa and reduced antigen dTpa booster vaccines were compared to a hepatitis A control vaccine in DTPa-primed toddlers aged 18–20 months. Post-booster, all DTPa and dTpa recipients were seroprotected against diphtheria and tetanus, and ≥93.3% had a booster response to pertussis. There were similar reactogenicity rates in the DTPa and dTpa vaccine recipients. Few Grade 3 symptoms were reported. Just over one in four children in the control group had diphtheria antibody at or potentially below the correlate of protection benchmark (0.016 IU/ml). Larger studies should evaluate potential benefits of reduced antigen vaccines and seroprotection in children who do not receive a booster dose of DTPa at this age, including protection against diphtheria until subsequent booster doses are given.     

Safety of diphtheria,tetanus, acellular pertussis and inactivated poliovirus (DTaP–IPV) vaccine

Background

In 2008, a diphtheria, tetanus, acellular pertussis, and inactivated poliovirus combined vaccine (DTaP–IPV) was licensed for use in children 4 through 6 years of age. While pre-licensure studies did not demonstrate significant safety concerns, the number vaccinated in these studies was not sufficient to examine the risk of uncommon but serious adverse events.

Objective

To assess the risk of serious adverse events following DTaP–IPV vaccination.

Methods

The study was conducted from January 2009 through September 2012 in the Vaccine Safety Datalink (VSD) project. In the VSD, electronic vaccination and encounter data are updated and aggregated weekly as part of ongoing surveillance activities. Based on previous reports and biologic plausibility, eight potential adverse events were monitored: meningitis/encephalitis; seizures; stroke; Guillain–Barré syndrome; Stevens–Johnson syndrome; anaphylaxis; serious allergic reactions other than anaphylaxis; and serious local reactions. Adverse event rates in DTaP–IPV recipients were compared to historical incidence rates in the VSD population prior to 2009. Sequential probability ratio testing was used to analyze the data on a weekly basis.

Results

During the study period, 201,116 children received DTaP–IPV vaccine. Ninety-seven percent of DTaP–IPV recipients also received other vaccines on the same day, typically measles–mumps–rubella and varicella vaccines. There was no statistically significant increased risk of any of the eight pre-specified adverse events among DTaP–IPV recipients when compared to historical incidence rates.

Conclusions

In this safety surveillance study of more than 200,000 DTaP–IPV vaccine recipients, there was no evidence of increased risk for any of the pre-specified adverse events monitored. Continued surveillance of DTaP–IPV vaccine safety may be warranted to monitor for rare adverse events, such as Guillain–Barré syndrome.     

Incidence of pertussis in subjects aged 50 years and older in France in 2013–2014

Objective

To assess the incidence of pertussis (whooping cough) in subjects aged 50 years and older in France.

Cost–benefit of the introduction of new strategies for vaccination against pertussis in Spain: Cocooning and pregnant vaccination strategies

BackgroundPertussis remains a public health problem in countries with high vaccination coverage. Classic vaccination approaches have failed to effectively control the infection. The incidence of pertussis hospitalizations in infants is high, especially in those younger than 3 months who are in high risk of a severe disease and death. Additional strategies are recommended for short-term protection of this vulnerable population. In this study, we estimated the impact of 2 strategies for pertussis prevention in infants younger than 1 year of age—a cocoon vaccination strategy and the vaccination of pregnant women (VPW)—and the cost–benefit of these approaches relative to the current vaccination policy in Spain.MethodsA cost–benefit analysis was conducted from the perspective of the publically-funded Spanish healthcare system, based on the yearly number of hospitalizations during the period of 2009 to 2011. We calculated the absolute risk reduction, the number of parents that would need to be vaccinated to prevent 1 hospitalization or death in infants <1 year, and the net benefit-to-cost ratio of each strategy.ResultsFrom 2009 to 2011, the incidence of pertussis in Spain was 153.44 hospitalizations per 100,000 infants <1 year. The absolute risk reduction for hospitalization would be 42.1/100,000 with cocooning and 75.2/100,000 with VPW. The number of parents needed to vaccinate with the cocoon strategy to prevent 1 pertussis hospitalization would be 4752 and to prevent 1 death, more than 900,000. With VPW, 1331 pregnant women would have to be vaccinated to prevent 1 hospitalization and 200,000 to prevent 1 death. The benefit-to-cost ratio was 0.04 for cocooning and 0.15 for VPW.     

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

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

Immunogenicity and reactogenicity of a decennial booster dose of a combined reduced-antigen-content diphtheria–tetanus–acellular pertussis and inactivated poliovirus booster vaccine (dTpa–IPV) in healthy adults

BackgroundPertussis in adults and adolescents could be reduced by replacing traditional tetanus and diphtheria (Td) boosters with reduced-antigen-content diphtheria–tetanus–acellular pertussis (dTpa) vaccines. This study evaluated the administration of dTpa–IPV (dTpa–inactivated poliovirus) in adults ten years after they received a booster dose of either dTpa–IPV, dTpa+IPV or Td–IPV in trial NCT01277705.MethodsOpen multicentre, phase IV study (www.clinicaltrials.gov NCT01323959) in which healthy adults, who had received a previous dose of dTpa–IPV, dTpa+IPV or Td–IPV ten years earlier, received a single decennial booster dose of dTpa–IPV (Boostrix™-polio, GlaxoSmithKline Vaccines). Blood samples were collected before and one month after booster vaccination. Antibody concentrations against all vaccine antigens were measured and reactogenicity and safety were assessed.ResultsA total of 211 subjects (mean age 50.3 years) received vaccination of whom 201 were included in the according-to-protocol cohort for immunogenicity. Before the decennial dTpa–IPV booster, ≥71.0% subjects were seroprotected/seropositive against all vaccine antigens. One month after the booster dose, all subjects were seroprotected against tetanus and poliovirus types 2 and 3; ≥95.7% subjects were seroprotected against diphtheria and ≥98.3% against poliovirus type 1. Anti-pertussis booster responses for the various antigens were observed in ≥76.5% (pertussis toxoid; PT), ≥85.1% (filamentous haemagglutinin; FHA) and ≥63.2% (pertactin; PRN) of subjects. During the 4-day follow-up, the overall incidence of local AEs was 71.6%, 75.0% and 72.2% in dTpa–IPV, dTpa+IPV and Td–IPV groups, respectively. Pain was the most frequent solicited local adverse event (AE; ≥62.7% subjects) and fatigue the most frequent solicited general AE (≥18.5%). No serious AEs were reported during the study.ConclusionA booster dose of dTpa–IPV was immunogenic and well tolerated in adults who had received a booster dose of either dTpa–IPV, dTpa+IPV or Td–IPV, ten years previously and supports the repeated administration of dTpa–IPV.     

Pertussis epidemiology including direct and indirect effects of the childhood pertussis booster vaccinations,Norway, 1998–2019

BackgroundThe acellular pertussis vaccine has been used in the Norwegian national immunisation program since 1998. Following an increase in pertussis incidence in all age groups, booster doses were introduced for 7–8-year-olds in 2006, and for 15–16-year-olds in 2013. We assessed the effects of the booster doses on pertussis incidence in different age groups to inform potential changes in vaccination policy.MethodsWe included all pertussis cases notified to the Norwegian Surveillance System for Communicable Diseases in 1998–2019. We calculated annual incidence rates (IR, per 100,000 inhabitants) by age group. We estimated average annual changes in IRs (incidence rate ratios, IRR) for each age group for 2006–2012 and 2013–2019 using Poisson regression.ResultsIn 1998–2019, 74,675 cases of pertussis were notified. Coinciding with booster introduction, between 2006 and 2012 the IR decreased among 8–15-year-olds (from 433 to 199/100,000, IRR 0.89 [95% confidence interval 0.88–0.90]). A similar decrease was seen between 2013 and 2019 among 16–19-year-olds (from 171 to 77/100,000, IRR 0.84 [0.82–0.86]). There was no significant change in IRs among children < 1 year of age between 2006 and 2012 (IRR 0.99 [0.95–1.04]) or 2013–2019 (IRR 0.96 [0.91–1.02]). The IR decreased in both periods among adults aged 20–39 and 40+ (IRR 0.94 [0.93–0.95] and 0.92 [0.91–0.92] in 2006–2012; IRR 0.97 [0.96–0.99] and 0.97 [0.96–0.99] in 2013–2019, respectively). Despite steady, high vaccination coverage, in 2013–2019, there was an increase in the IR among children aged 1–7 (63 to 86/100,000, IRR 1.05 [1.03–1.07]) and 8–15 years (88 to 122/100,000, IRR 1.08 [1.06–1.10]).ConclusionsPertussis booster doses have offered direct protection in the targeted age groups. Our findings suggest indirect protection in adults, while the incidence in infants hasn’t changed. The recent increase in IRs among 1–15-year-olds warrants close monitoring and further evaluation of the vaccination schedule.     

Safety and immunogenicity of a hexavalent diphtheria–tetanus–acellular pertussis–inactivated poliovirus–Haemophilus influenzae b conjugate–hepatitis B vaccine at 2, 3, 4, and 12–14 months of age

Combination vaccines improve parental and provider satisfaction and schedule compliance by decreasing the number of injections. In a Phase 2, randomized, double-blind, multicenter study, we compared four formulations of a liquid, hexavalent diphtheria–tetanus–acellular pertussis–inactivated poliovirus–Haemophilus influenzae b conjugate–hepatitis B virus (DTaP–IPV–Hib–HBV) vaccine in 708 infants immunized at 2, 3, 4, and 12–14 months of age. The formulations contained identical DTaP and IPV components, differing in the contents of Hib polyribosylribitol phosphate (PRP) conjugate component (tetanus-toxoid [PRP-T, 12 μg] or Neisseria meningitidis outer-membrane-protein-complex [PRP-OMPC, 3 μg or 6 μg]), and in hepatitis B surface antigen (HBsAg, 10 μg or 15 μg). A minimum acceptable postdose 3 antibody response rate was defined by the lower limit of the 95% confidence interval exceeding a prespecified target. Rates of adverse events (AEs) were similar among groups, with a trend for increased solicited injection-site reactions (pain, redness, swelling) with increasing PRP-OMPC and HBsAg concentration. Serious AEs reported by eight subjects were not considered to be vaccine related. All PRP-OMPC formulations met prespecified acceptability criteria for postdose 3 immunogenicity for all antigens: PRP, HBsAg, pertussis, diphtheria, tetanus and polio. Apart from the Hib response, the postdose 3 responses obtained with the PRP-T formulation met the acceptability criterion for each antigen. Postdose 4 responses were acceptable for all antigens in all formulations. All vaccine formulations were well tolerated. The three PRP-OMPC formulations met prespecified immunogenicity criteria, and the one with the lowest PRP-OMPC concentration was selected for further optimization of immunogenicity.     

Incidence and mortality of pertussis disease in infants <12 months of age following introduction of pertussis maternal universal mass vaccination in Bogotá, Colombia

BackgroundMaternal immunization with tetanus, diphtheria, and acellular pertussis (Tdap) vaccine confers protection to young infants. We aimed to describe trends in pertussis incidence and associated mortality in children aged <12 months before and after introduction of maternal Tdap immunization in Bogotá, Colombia.MethodsData on pertussis-related cases/deaths in infants aged <12 months were collected from SIVIGILA for the period 2005–2016, and compared incidence for the pre-vaccine introduction (2005–2012) and post-maternal Tdap vaccination (2014–2016) periods in infants aged <12 months and in three distinct age-strata; ≤6 weeks, 7–<28 weeks, and 28–52 weeks. Mortality comparisons were performed in all infants <12 months.ResultsFrom 2005 to 2016, 2315 laboratory or clinically-confirmed pertussis cases were reported in infants <12 months of age (278 cases in young infants aged ≤6 weeks); 55 pertussis deaths were reported in children aged <12 months. No pertussis deaths were reported in the 2014–2016 period. Since maternal Tdap introduction in 2013, a consistent decline in pertussis incidence and mortality was observed. In the time-series analysis, incidence declined from 209.4/100,000 persons (2005–2012) to 49.1/100,000 persons (2014–2016) in all children <12 months; a 87.5% (95%CI: 77.2-93.2%) reduction. For these same period’s incidence in young infants ≤6 weeks declined from 196.7 to 89.6/100,000 person-years (an 54.4% [95% CI: 35.4–67.9%] reduction). Greater incidence reductions were observed in older infants; 73.4% (95% CI: 68.4–77.6%) in those aged 7–<28 weeks, and 100% in those aged 28–52 weeks. A 100% reduction in Pertussis mortality in infants <12 months was observed. Since Tdap introduction, maternal vaccine coverage rose from <60% in 2013–2015 to 80% in 2016.ConclusionsImplementation of maternal immunization in Bogotá may have contributed to the reduction in pertussis incidence and mortality among infants <12 months of age (ClinicalTrials.gov: NCT02569879).An Audio Summary linked to this article that can be found on Figshare https://doi.org/10.6084/m9.figshare.12943316     

Immunogenicity and safety of a tetanus toxoid,reduced diphtheria toxoid and three-component acellular pertussis vaccine in adults 19–64 years of age

Purpose

This study was conducted to assess the immunogenicity and safety of a tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine containing three pertussis antigens (Boostrix^®, Tdap3v), currently licensed in the US for use in adolescents 10–18 years of age, in adults 19–64 years of age.

Methods

2284 healthy adults, aged 19–64 years, were randomized to receive a single dose of Tdap vaccine, either Tdap3v or a five-pertussis component Tdap vaccine (Adacel^®, Tdap5v) licensed for adult use in the US. Blood samples were taken before and 1 month after vaccination. Reactogenicity was assessed for 15 days after vaccination.

Results

Tdap3v was comparable to Tdap5v in eliciting seroprotective levels of antibodies to diphtheria and tetanus toxoids, with >98% of subjects having post-vaccination seroprotective antibody levels (≥0.1 IU/mL) against diphtheria or tetanus toxoids. The pertussis components of Tdap3v were shown to be immunogenic in adults, with booster responses to pertussis toxoid (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) observed in 77.2%, 96.9%, and 93.2%, respectively, of Tdap3v recipients, and in 47.1%, 94.0%, and 91.7%, respectively, of Tdap5v recipients. Anti-pertussis antibody GMCs in Tdap3v recipients exceeded those observed in infants following primary DTaP vaccination, in whom efficacy against pertussis disease was subsequently demonstrated. Injection site reactions (pain, redness, and swelling) and fever ≥37.5 °C (99.5 °F) were reported significantly more often (p < 0.05) by Tdap5v recipients than by Tdap3v recipients. Fatigue preventing normal daily activities was reported by a small but significantly greater percentage of Tdap3v recipients (2.5%) than Tdap5v recipients (1.2%, p < 0.05).

Conclusion

In adult recipients, Tdap3v was comparable to an approved Tdap vaccine in providing seroprotection against diphtheria and tetanus, and produced immune responses to pertussis antigens consistent with protection against disease. The overall safety profile of Tdap3v was generally comparable to that of Tdap5v [NCT #106316].     

An assessment of the safety of adolescent and adult tetanus–diphtheria–acellular pertussis (Tdap) vaccine,using active surveillance for adverse events in the Vaccine Safety Datalink

Using a new sequential analytic method, the safety of tetanus–diphtheria–acellular pertussis (Tdap) vaccine was monitored weekly among subjects aged 10–64 years during 2005–2008. Encephalopathy–encephalitis–meningitis, paralytic syndromes, seizures, cranial nerve disorders, and Guillain-Barré syndrome were selected as outcomes based on previous reports and biologic plausibility. The risk following Tdap was not significantly higher than the risk after Td. Statistical power was sufficient to detect a relative risk of 4–5 for Guillain-Barré syndrome and 1.5–2 for the other outcomes. This study provides reassurance that Tdap is similar in safety to Td regarding the outcomes studied and supports the viability of sequential analysis for post-licensure vaccine safety monitoring.     

Is pertussis being considered as a cause of persistent cough among adults?

A study was conducted to determine the 1124 French Sentinel network general practitioners ability to consider pertussis as a cause of persistent cough among adults. Pertussis was rarely considered in the differential diagnosis of cough (6%). Factors associated with pertussis being considered included younger age, shorter cough duration, world health organization clinical definition for pertussis, and muscular chest pain.     

The effect of timing of maternal tetanus,diphtheria, and acellular pertussis (Tdap) immunization during pregnancy on newborn pertussis antibody levels – A prospective study

Background

The Centers for Disease Control and Prevention recommend Tdap immunization during pregnancy, preferably at 27–36 weeks.

Aim

To ascertain whether there is a preferential period of maternal Tdap immunization during pregnancy that provides the highest concentration of pertussis-specific antibodies to the newborn.

Methods

This prospective study measured pertussis-specific antibodies in paired maternal-cord sera of women immunized with Tdap after the 20th week of their pregnancy (n = 61).

Results

The geometric mean concentrations (GMCs) of Immunoglobulin G (IgG) to pertussis toxin (PT) were higher in the newborns’ cord sera when women were immunized at 27–30⁺⁶ weeks (n = 21) compared with 31–36 weeks (n = 30) and >36 weeks (n = 7), 46.04 international units/milliliter (IU/mL) (95% CI, 24.29–87.30) vs. 8.69 IU/mL (95% CI, 3.66–20.63) and 21.12 IU/mL (95% CI, 7.93–56.22), p < 0.02, respectively. The umbilical cord GMCs of IgG to filamentous hemagglutinin (FHA) were higher in the newborns’ cord sera when women were immunized at 27–30⁺⁶ weeks compared with 31–36 weeks and >36 weeks, 225.86 IU/mL (95% CI, 182.34–279.76) vs. 178.31 IU/mL (95% CI, 134.59–237.03) and 138.03 IU/mL (95% CI, 97.61–195.16), p < 0.02, respectively.

Conclusions

Immunization of pregnant women with Tdap between 27–30⁺⁶ weeks was associated with the highest umbilical cord GMCs of IgG to PT and FHA compared with immunization beyond 31 weeks gestation. Further research should be conducted to reaffirm these finding in order to promote an optimal pertussis controlling policy.     

The incidence of pertussis hospitalizations among Japanese infants: excess hospitalizations and complications?

We examined pertussis hospitalizations among infants aged <1 year between 2006 and 2008 using the nationwide inpatient database in Japan. A total of 660 infants hospitalized for pertussis were identified. Peak incidence occurred at age 1 month and infants aged 0-2 months (too young for pertussis vaccination) and ≥3 months (eligible for at least one dose of vaccination) accounted for 44·5% and 55·5% of hospitalizations, respectively. Complications related to pertussis were found in 165 (25·0%) cases, including one death; the age at admission did not differ significantly between patients with and those without complications (mean age 4·1 vs. 4·5 months, P=0·12). Seventeen patients required mechanical ventilation. Of the 17 cases, 14 infants were aged <3 months and three infants were aged ≥3 months. Our findings highlight that the vaccination schedule against pertussis may often be delayed in Japan.     

Trends in Canadian infant pertussis hospitalizations in the pre- and post-acellular vaccine era, 1981–2016

ObjectiveThe acellular pertussis vaccine was introduced into the routine childhood immunization schedule across Canada in 1997–98 and adolescent booster doses were added between 1999 and 2005. We sought to assess the impact of these changes on infant pertussis hospitalizations and admissions to intensive care units (ICU) in Canada.MethodsHospitalizations with a primary diagnosis of pertussis were extracted from the Canadian Discharge Abstract Database (DAD) for cases with hospital discharge dates between 1981 and 2016 using relevant ICD-9 and ICD-10 codes. Only cases with age less than one year at time of admission were included. Disease severity was assessed by admission to ICU. Cases were categorized into two periods: pre-program implementation period (1981–1995) and the post-program implementation period (2006–2016). Incidence rates, risk ratios, and rate differences were calculated for each period and comparisons for the two periods were done using chi-squared and t-tests. Quasi Poisson analysis was used to investigate trends.ResultsWhen comparing the pre- and post-implementation periods, the average annual hospitalization rates for infants less than 1 year declined from 165.1 (95% CI 161.3, 168.9) to 33.6 (95% CI 31.6, 35.6) pertussis-related admissions per 100,000 population, with a corresponding reduction in the risk ratio of 4.9 (95% CI 4.6, 5.2). The risk of admission into an ICU was 1.58 times higher in the pre- versus post-implementation period while the highest reduction in average annual hospitalizations was 263.3 admissions per 100,000 population in infants 2 months of age. In the post-implementation period, infants less than 1 month of age had the highest average annual hospitalization rate at 126.6 (95% CI 113.1, 140.1) hospitalizations per 100,000 infants.ConclusionInfant pertussis hospitalizations have reduced greatly over time. Infants under 2 months of age remain the most at-risk age group for hospitalization and admission to ICU.     

The resurgence of pertussis in developed countries: a problem for Brazil as well?

Pertussis is currently considered an important public health problem in developed countries. In most of these countries, mass immunization for pertussis was initiated in the 1950s and was followed by a marked decrease in disease incidence. In the 1970s, pertussis was apparently under control in countries were vaccine coverage was maintained high. However, in the last two decades of the 20th century, the number of reported cases increased in all age groups, including adolescents and adults, indicating resurgence of the disease. This brief note aims to present the possible reasons for resurgence of this disease and to discuss the prospects of its future dynamics in Brazil. There has been no evidence to date for the resurgence of pertussis in Brazil. However, since mass immunization in Brazil began only in the 1980s, one cannot rule out the possibility that pertussis will resurge in the near future. Therefore, it is important that public health services closely monitor the epidemiological situation of pertussis in order, if necessary, to rapidly update the current immunization strategy.     

Cost–benefit analysis of hospital based postpartum vaccination with combined tetanus toxoid,reduced diphtheria toxoid,and acellular pertussis vaccine (Tdap)

Objective

To assess the economic benefits associated with hospital-based postpartum Tdap (combined tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis) vaccination.

Methods

A decision tree model was constructed to calculate the potential cost–benefit of this strategy from both a health care system and a societal perspective. Probabilities and costs were derived from published literature, data reported to Centers for Disease Control and Prevention, and recommendations from expert panels. The maternal vaccination protection period for infants was defined as 7 months, and 10 years of waning immunity following Tdap for birth mothers was estimated in the model. All cost estimates were inflated to year 2012 US dollars and discounted at a 3% annual discount rate.

Results

In the base case from a societal perspective, the expected costs per vaccinated and unvaccinated mother were estimated at $129.27 and $187.97, respectively, suggesting an expected net benefit of $58.70 per vaccinated mother. The overall societal benefits in the cohort of 3.6 million U.S. birth mothers ranged from $52.8–126.8 million, depending on the vaccination coverage level. If including direct medical costs only, the strategy would not generate net savings from a health care system perspective. Annual incidence of pertussis in birth mothers and Tdap efficacy exhibited substantial impact on the model as shown in one-way and two-way sensitivity analyses.

Conclusions

Although postpartum Tdap vaccination is not cost-beneficial from a health care system perspective in the base case, this strategy is likely to generate net benefits from a societal perspective.