Brand-specific rates of pertussis disease among Wisconsin children given 1–4 doses of pertussis Vaccine, 2010–2014

BackgroundAcellular pertussis vaccines were initially licensed based on placebo-controlled efficacy trials, but such trials are no longer ethical. The effectiveness of current pertussis vaccines among properly vaccinated children <5 years is so high that a randomized trial is infeasible. Fluctuations in pertussis incidence and characteristics of the US vaccine marketplace make selection of suitable controls for a case-control study problematic. To satisfy an FDA requirement to evaluate rates of pertussis following licensure of Pentacel® vaccine, we used a case-cohort study design with a novel method for characterizing the cohort population.MethodsThis prospective, observational study was conducted in Wisconsin from 2010 to 2014 among Wisconsin residents <60 months of age who received ≤four doses of pertussis vaccine (surveillance population). Cases were identified by the Wisconsin Division of Public Health. Characteristics and pertussis vaccinations of the surveillance population were estimated by ongoing random telephonic survey. The primary objective was to determine rates of pertussis disease among those who received only Pentacel vaccine (Group 1) vs those who received a single brand of vaccine other than Pentacel vaccine (Group 2).Results1195 pertussis cases were identified. It was estimated that the surveillance population accrued a total of 1,133,403 person-years (Group 1, 39%; Group 2, 41%; Group 3 [those not in Group 1 or Group 2], 20%). Pertussis rates were similar in Group 1 (98.9/100,000) and Group 2 (96.2/100,000); rate ratios were 1.03 (unadjusted; 90% CI, 0.92–1.15) and 0.99 (adjusted; 90% CI, 0.89–1.12). Persons with one or more delayed vaccinations had a 66% higher risk of pertussis (90% CI, 39–96%).DiscussionPertussis protection was not found to differ for recipients of the newly licensed vs other available pertussis vaccines. Delayed vaccination substantially increased risk of pertussis. Sample survey methodology was able to characterize the study cohort and enable an otherwise-infeasible study.Clinical Trial Registry number: ClinicalTrials.gov, NCT01129362.     

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.     

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.     

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.

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.     

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.     

Can vaccine legacy explain the British pertussis resurgence?

Pertussis incidence has been rising in some countries, including the UK, despite sustained high vaccine coverage. We questioned whether it is possible to explain the resurgence without recourse to complex hypotheses about pathogen evolution, subclinical infections, or trends in surveillance efficiency. In particular, we investigated the possibility that the resurgence is a consequence of the legacy of incomplete pediatric immunization, in the context of cohort structure and age-dependent transmission. We constructed a model of pertussis transmission in England and Wales based on data on age-specific contact rates and historical vaccine coverage estimates. We evaluated the agreement between model-predicted and observed patterns of age-specific pertussis incidence under a variety of assumptions regarding the duration of immunity. Under the assumption that infection-derived immunity is complete and lifelong, and regardless of the duration of vaccine-induced immunity, the model consistently predicts a resurgence of pertussis incidence comparable to that which has been observed. Interestingly, no resurgence is predicted when infection- and vaccine-derived immunities wane at the same rate. These results were qualitatively insensitive to rates of primary vaccine failure. We conclude that the alarming resurgence of pertussis among adults and adolescents in Britain and elsewhere may simply be a legacy of historically inadequate coverage employing imperfect vaccines. Indeed, we argue that the absence of resurgence at this late date would be more surprising. Our analysis shows that careful accounting for age dependence in contact rates and susceptibility is prerequisite to the identification of which features of pertussis epidemiology want additional explanation.     

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.     

Bordetella pertussis (Bp) disease: Before (2003–2011) and after (2013–2016) maternal immunization strategy in a pediatric hospital

IntroductionWhooping cough continues to be a major cause of morbidity and mortality in infants younger than 1 year. In 2012, Argentina introduced Tdap in pregnancy to prevent infant mortality. The aim of this study is to describe the impact of maternal immunization on the hospitalization and mortality rates of confirmed Bordetella pertussis (Bp) cases by comparing pre- and post-Tdap vaccine recommendation periods.Material and MethodsAll PCR-confirmed Bp cases from “R. Gutierrez” Children's Hospital identified between December 2003 and December 2016 were included in. Analysis was performed comparing hospitalization rates (per 10,000 discharges) between pre-vaccination (PreV) 2003–2011 and post-vaccination (PostV) 2013–2016 time periods, excluding the intervention year (2012).ResultsDuring the study time frame, there were 1046 suspected Bp cases, of which 337 (32.2%) were confirmed. Three-hundred eight cases were analyzed (excluding year 2012): 237 in PreV and 71 in PostV. In comparison with PreV, PostV cases were older (3 vs 9 months; p < 0.001), and required less hospitalization (86.9% vs 67.6%; p < 0.001). Bp hospitalization rate (HR) decreased (22.3 vs 11.6; p < 0.001). The mortality rate in PreV 5.9% (14 cases); there were not deaths during PostV (p = 0.036).ConclusionsConfirmed cases were among infants younger than 1 year In PostV, Bp cases were older and there was a significant decrease in the hospitalization rate. There were no fatal cases in our center after the pregnancy Tdap recommendation was implemented.     

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.     

Is pertussis actually reemerging? Insights from an individual-based model

In this paper, we introduce a spatially explicit, individual-based model developed to simulate the dynamics of pertussis in a small population. With this simulation approach, complex epidemic systems can be built using information on parasite population structure (strain diversity, virulence diversity, etc.), human population structure (individual risk, age structure, interaction matrices, immune response, etc.), as well as mechanisms of evolution and learning. We parameterized our model to describe pertussis in an age-structured community. Pertussis or whooping cough is an acute infection of the respiratory tract caused by Bordetella pertussis. Despite wide-scale vaccination in many countries, this disease is reemerging throughout the world in both adults and children. Emergence has been explained by many factors: wane of vaccine and natural immunity, increase of asymptomatic carriers, and/or natural selection of non-vaccine strains. Here, we model these hypotheses and analyze their potential impact on the observed increase of pertussis notification.     

Risk factors for pertussis hospitalizations in Australians aged 45 years and over: A population based nested case–control study

Although studies have described factors associated with pertussis hospitalization in children, data on adult hospitalization are sparse. We examined the association between patient characteristics and hospitalization among older adults with pertussis. We conducted a nested case–control study of participants in the 45 and Up prospective cohort in New South Wales, Australia, with an incident pertussis diagnosis during 2006–2012. Cases were defined as those with a hospitalization coded as ‘whooping cough’ or ‘non-specific respiratory disease/cough’ between a week prior and 6 weeks after the diagnosis of pertussis based on laboratory tests. Controls were participants diagnosed with pertussis but not hospitalized. Among 265,287 participants, the incidence of pertussis and pertussis hospitalization was 83.9 (95% [confidence interval] CI, 78.7–89.6) and 2.9 (95% CI, 2.1–4.1)/100,000 person-years, respectively. Among 33 cases and 882 controls, factors associated with hospitalization were increasing age (compared to those 45–54 years, adjusted odds ratio [aOR] 5.4 (95% CI, 1.6–18.2) and 8.9 (95% CI, 2.3–34.7) in those aged 65–74 years and 75+ years, respectively) and smoking (ever versus never, aOR 2.37 (95% CI, 1.11–5.06)). The risk of pertussis hospitalization is substantially higher in ≥65 years old. A booster dose of diphtheria–tetanus–pertussis vaccine could be readily integrated into routine vaccination for this age group.     

What predicts postpartum pertussis booster vaccination? A controlled intervention trial

Background‘Cocooning’ aims to protect susceptible infants from pertussis via caregiver vaccination. Control trials evaluating educational interventions to promote cocooning are lacking. We evaluated the role of message-framing vs. standard health information in promoting pertussis vaccination.MethodsWe recruited postpartum women from a maternity hospital in Sydney, Australia (November 2010–July 2012). Participants self-completed a pertussis knowledge and attitudes questionnaire. We then assigned pertussis-susceptible (no pertussis vaccine ≤10 years) participants to receive a gain-framed, loss-framed pamphlet or control (Government Pertussis factsheet) using weekly sequential block allocation. Next, participants were offered a pertussis vaccine (dTpa) and completed a post-questionnaire on discharge.ResultsA baseline questionnaire was completed for 96.4% (1433/1486) of postpartum women approached. Missing data was excluded (n = 29). Next, participants (1404) were screened for vaccine status: 324 (23%) reported prior pertussis booster vaccine receipt, leaving 1080 participants requiring vaccination. Among susceptible mothers, 70% (754/1080) were vaccinated post-intervention. Rates were similar between ‘gain’, ‘loss’ or ‘control’ pamphlets (69.1% vs. 71.8% vs. 68.8%; p = 0.62). Intention to be vaccinated (OR 2.46, p < 0.001; 95% CI: 1.69–3.58), perceived vaccine benefits (OR: 1.61, p < 0.001; 95% CI: 1.25–2.15) and having received a vaccine recommendation (OR 1.68; p = 0.025; 95% CI: 1.07–2.65) were independent predictors of vaccine uptake. At discharge, overall pertussis vaccine coverage had increased from 23% to 77% among women screened (1078/1404).ConclusionA cocooning strategy for pertussis vaccination can be highly effective when partially implemented within maternity hospitals, with information accompanied by a funded vaccine. Mothers were highly receptive to vaccination in the postnatal ward: facts about pertussis were as effective as message-framing in promoting a high uptake of 70%. Perceived vaccine benefits, intentions and vaccine recommendation were important predictors of uptake. Our intervention trial increased the existing pertussis vaccine coverage of 23–77%.     

U.S. Postlicensure safety surveillance for adolescent and adult tetanus,diphtheria and acellular pertussis vaccines: 2005–2007

Background

Pre-licensure clinical trials for two U.S. licensed tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccines did not reveal any major safety concerns. However, routine use in large adolescent and adult populations could reveal rare and potentially serious adverse events (AEs).

Methods

To characterize reported AEs following Tdap vaccination and identify potential safety concerns warranting further evaluation, we analyzed data from the Vaccine Adverse Event Reporting System (VAERS) and assessed the frequency and proportions of AEs and reporting rates (reports per 100,000 vaccine doses distributed).

Results

A total of 2090 reports (7% were serious; 55% listed Tdap alone) involving Tdap vaccines were submitted to VAERS May 2005–June 2007. The crude reporting rate was 10.2 per 100,000 vaccine doses distributed. The median age of vaccinees was 22 years, and the female to male ratio was about 2 to 1. The majority of reports described common local and systemic signs and symptoms, such as injection site reactions, fever, and headache. Rarely reported AEs included myopericarditis, demyelinating diseases of the central nervous system, Guillain–Barré Syndrome, syncope, encephalopathy/encephalitis, seizure, Bell's palsy, anaphylaxis, and thrombocytopenia.

Conclusions

Because adolescents and adults were not routinely vaccinated against pertussis in the past, this surveillance summary provides important – and reassuring – information about the use of Tdap in these age groups. Although subject to the limitations of passive surveillance, the findings of this VAERS review support the pre-licensure clinical trial data with regard to the safety of the U.S. licensed Tdap vaccines. Continued monitoring of clinically significant AEs that are temporally associated with Tdap vaccination and further assessment of such events using controlled observational studies may provide additional information about the safety of these vaccines.     

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.