Vaccination of adults 65 years of age and older with tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Boostrix(®)): results of two randomized trials

Background

Pertussis can cause significant morbidity in elderly patients, who can also transmit this disease to infants and young children. There is little data available on the use of acellular pertussis vaccines in recipients ≥65 years of age.

Methods

Two studies examined the safety and immunogenicity of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine (Boostrix^®) in healthy ≥65 year olds. In Study A subjects received single doses of Tdap and seasonal influenza vaccine either co-administered or given one month apart. In Study B subjects received either Tdap or tetanus-diphtheria (Td) vaccine. Antibodies were measured before and one month after vaccination. Reactogenicity and safety were actively assessed using diary cards.

Results

A total of 1104 subjects 65 years of age and older received a Tdap vaccination in the two studies. In study A, no differences in immune responses to Tdap or influenza vaccine were observed between co-administered or sequentially administered vaccines. In study B, Tdap was non-inferior to Td with respect to diphtheria and tetanus seroprotection, and anti-pertussis GMCs were non-inferior to those observed in infants following a 3-dose diphtheria, tetanus and acellular pertussis (DTaP) primary vaccination series, in whom efficacy against pertussis was demonstrated. Reports of adverse events were similar between Tdap and Td groups.

Conclusions

Tdap was found to be immunogenic in subjects ≥65 years, with a safety profile comparable to US-licensed Td vaccine. Tdap and influenza vaccine may be co-administered without compromise of either the reactogenicity or immunogenicity profiles of the two vaccines.     

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

Persistence of antibodies after a single dose of Tdap vaccine (tetanus, diphtheria, and 5-component acellular pertussis vaccine) was evaluated in a follow-up study of adolescents (N=324) and adults (N=644) who had received Tdap in earlier clinical trials. Outcome measures were seroprotection (tetanus and diphtheria) or seropositivity (pertussis) and geometric mean concentrations. Humoral immune responses to all antigens were robust 1 month after initial immunization, decreased at subsequent measurements, but continued to exceed pre-immunization levels 1, 3, 5, and 10 years later. Protective levels of diphtheria and tetanus antitoxin persisted in 99.3% of adolescents 10 years after a booster dose of Tdap. Seropositivity to 1 or more pertussis antigens also persisted in most adolescents for 10 years. Although tetanus antitoxin responses were similar in adults to those observed in adolescents, diphtheria antitoxin titers were lower, reflecting the fact that a smaller proportion of adults had received diphtheria toxoid in the previous 10 years compared to adolescents. These data will contribute to the selection of the optimal interval for repeat doses of Tdap.     

Pertussis immunization in paediatric healthcare workers: Knowledge,attitudes, beliefs,and behaviour

Healthcare workers’ (HCWs) knowledge, attitudes, and beliefs regarding pertussis immunization were assessed and compared to the rate of vaccine uptake. A questionnaire was distributed to employees at a paediatric and maternity tertiary care centre. Respondents were then offered a dose of the tetanus, diphtheria, and acellular pertussis vaccine (Tdap) at a free vaccine clinic. In total, 529 out of 3051 (17%) employees completed the survey and 61 received the Tdap vaccine. Although 76% of participants were willing to be immunized, only 15% presented to the clinic. There is a widespread acceptance of pertussis immunization among paediatric HCWs. Stated intentions may be poorly predictive of behaviour. Education and institutional or public funding may improve vaccine uptake.     

Increasing postpartum rate of vaccination with tetanus,diphtheria, and acellular pertussis vaccine by incorporating pertussis cocooning information into prenatal education for group B streptococcus prevention

BackgroundTo evaluate whether incorporating pertussis cocooning information into prenatal education for group B streptococcus (GBS) prevention increased postpartum rate of vaccination with tetanus, diphtheria, and acellular pertussis (Tdap) vaccine.MethodsWe performed a retrospective pre-intervention/post-intervention study of postpartum women at a teaching hospital in Taiwan. We compared the frequency of Tdap vaccination during the pre-intervention (May 1, 2009 to December 31, 2010) and post-intervention (March 1, 2011–March 31, 2012) time periods. The clinical intervention was incorporation of pertussis cocooning information into prenatal education for GBS prevention to pregnant women presented during a prenatal visit at 35–37 weeks of gestation. Postpartum Tdap vaccination rate during the pre-intervention and post-intervention periods was compared. We also specifically examined group differences in the percentage of women who received postpartum Tdap vaccination to explore factors that influenced their decision regarding Tdap vaccine.ResultsTdap vaccination was more likely during the post-intervention period compared with the pre-intervention period (2268 of 3186 [71.2%] compared with 2556 of 5030 [55.6%]; p < .001). Comparisons between each subgroup of pre-intervention and post-intervention women showed that incorporating pertussis information into prenatal education for GBS prevention was beneficial except for women of maternal age 30–34 years and women living in rural areas.ConclusionsPrenatal GBS screening activities represent an opportunity for healthcare providers to offer pertussis cocooning information to eligible pregnant women to improve rates of postpartum Tdap vaccination.     

Evaluation of two vaccine education interventions to improve pertussis vaccination among pregnant African American women: A randomized controlled trial

BackgroundVaccination coverage with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine in pregnancy or immediately postpartum has been low. Limited data exist on rigorously evaluated interventions to increase maternal vaccination, including Tdap. Tailored messaging based on the Elaboration Likelihood Model (ELM) framework has been successful in improving uptake of some public health interventions. We evaluated the effect of two ELM-based vaccine educational interventions on Tdap vaccination among pregnant African American women, a group of women who tend to have lower vaccine uptake compared with other groups.MethodsWe conducted a prospective randomized controlled trial to pilot test two interventions – an affective messaging video and a cognitive messaging iBook – among pregnant African American women recruited during routine prenatal care visits. We measured Tdap vaccination during the perinatal period (during pregnancy and immediately postpartum), reasons for non-vaccination, and intention to receive Tdap in the next pregnancy.ResultsAmong the enrolled women (n = 106), 90% completed follow-up. Tdap vaccination in the perinatal period was 18% in the control group; 50% in the iBook group (Risk Ratio [vs. control group]: 2.83; 95% CI, 1.26–6.37), and 29% in the video group (RR: 1.65; 95% CI, 0.66–4.09). From baseline to follow-up, women’s reported intention to receive Tdap during the next pregnancy improved in all three groups. Among unvaccinated women, the most common reason reported for non-vaccination was lack of a recommendation for Tdap by the woman’s physician.ConclusionsEducation interventions that provide targeted information for pregnant women in an interactive manner may be useful to improve Tdap vaccination during the perinatal period. However, larger studies including multiple racial and ethnic groups are needed to evaluate robustness of our findings.Trial Registration: clinicaltrials.gov Identifier: NCT01740310.     

Predictors of tetanus,diphtheria, acellular pertussis and influenza vaccination during pregnancy among full-term deliveries in a medically underserved population

ObjectiveTo evaluate predictors of vaccination among women who received tetanus, diphtheria, and acellular pertussis vaccination (Tdap), influenza vaccination, and Tdap and influenza vaccinations.Study DesignIn a retrospective cohort study of all full-term (≥37 weeks gestation) deliveries between July 1, 2016 and June 30, 2018 at a single, safety-net institution, we used multinomial logistic regression models to compare predictors of vaccination among women who received Tdap only, influenza only, and both Tdap and influenza vaccines.ResultsAmong 3132 full-term deliveries, women were primarily non-Hispanic black (67.5%), between the ages of 21–34 (65.3%), and multiparous (76.0%). The rates of only influenza or Tdap vaccination were 10.3% and 21.6%, respectively; 43.3% of women received both vaccines, and 24.9% of women did not receive either vaccine. In the adjusted models, Hispanic ethnicity was positively associated with receipt of all types of vaccination and non-Spanish language interpreter use was positively associated with receipt of Tdap vaccination and Tdap and influenza vaccination. A parity of greater than three and inadequate and unknown prenatal care adequacy were negative predictors of all types of vaccination. Pre-existing hypertension was negatively associated with Tdap vaccination, and HIV-positive status was negatively associated with influenza vaccination and Tdap and influenza vaccination.ConclusionCompared to the national rate of both Tdap and influenza vaccination (32.8%), a higher proportion of women received both vaccines in our study population. Vaccine uptake may be affected by race/ethnicity, use of interpreter services, parity, pre-existing comorbidities, and prenatal care adequacy. The lower rate of influenza vaccination compared to Tdap vaccination suggests that other factors, such as vaccine hesitancy and mistrust, may be differentially impacting influenza vaccination uptake in our predominantly minority population. Future provider and public health approaches to vaccine promotion should incorporate culturally appropriate strategies that address vaccine-related beliefs and misconceptions.     

Improving influenza and Tdap vaccination during pregnancy: A cluster-randomized trial of a multi-component antenatal vaccine promotion package in late influenza season

BackgroundEvidence-based interventions to improve influenza vaccine coverage among pregnant women are needed, particularly among those who remain unvaccinated late into the influenza season. Improving rates of antenatal tetanus, diphtheria and acellular pertussis (Tdap) vaccination is also needed.PurposeTo test the effectiveness of a practice-, provider-, and patient-focused influenza and Tdap vaccine promotion package on improving antenatal influenza and Tdap vaccination in the obstetric setting.MethodsA cluster-randomized trial among 11 obstetric practices in Georgia was conducted in 2012–2013. Intervention practices adopted the intervention package that included identification of a vaccine champion, provider-to-patient talking points, educational brochures, posters, lapel buttons, and iPads loaded with a patient-centered tutorial. Participants were recruited from December 2012–April 2013 and included 325 unvaccinated pregnant women in Georgia. Random effects regression models were used to evaluate primary and secondary outcomes.ResultsData on antenatal influenza and Tdap vaccine receipt were obtained for 300 (92.3%) and 291 (89.5%) women, respectively. Although antenatal influenza and Tdap vaccination rates were higher in the intervention group than the control group, improvements were not significant (For influenza: risk difference (RD) = 3.6%, 95% confidence interval (CI): −4.0%, 11.2%; for Tdap: RD = 1.3%, 95% CI: −10.7%, 13.2%). While the majority of intervention package components were positively associated with antenatal vaccine receipt, a provider's recommendation was the factor most strongly associated with actual receipt, regardless of study group or vaccine.ConclusionsThe intervention package did not significantly improve antenatal influenza or Tdap vaccine coverage. More research is needed to determine what motivates women remaining unvaccinated against influenza late into the influenza season to get vaccinated. Future research should quantify the extent to which clinical interventions can bolster a provider's recommendation for vaccination. This study is registered with clinicaltrials.gov, study ID NCT01761799.     

Immunogenicity and reactogenicity of co-administered tetanus-diphtheria-acellular pertussis (Tdap) and tetravalent meningococcal conjugate (MCV4) vaccines compared to their separate administration

In the United States, co-administration of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine and tetravalent meningococcal conjugate vaccine (MCV4) is recommended in adolescents. In this clinical study, 1341 adolescents received Tdap (Boostrix® GlaxoSmithKline) and MCV4 (Menactra®, Sanofi-Pasteur) simultaneously or sequentially one month apart. Co-administration of Tdap + MCV4 was well tolerated and immunogenic, resulting in high levels of antibodies against diphtheria, tetanus, pertussis and meningococcal serogroup A,C,W-135 and Y antigens. The data provide support for current recommendations for co-administration of Tdap and MCV4 vaccines at the same office visit.     

Patient attitudes toward influenza and tetanus,diphtheria and acellular pertussis vaccination in pregnancy

BackgroundRoutine influenza and tetanus, diphtheria and acellular pertussis (Tdap) vaccination of pregnant women to prevent poor maternal, fetal and neonatal outcomes is recommended practice; however, actual rates of influenza vaccine acceptance are typically well below the (Healthy People 2020, 2015) goal of 80%.ObjectiveWe sought to identify barriers to accepting either vaccination.Materials and MethodsFrom December 2014 to April 2015 women were given a questionnaire eliciting their experiences, attitudes and history of influenza and Tdap vaccination in pregnancy during their routine prenatal care appointments at a tertiary care center. Patient demographics were included in the questionnaire. A similar questionnaire was administered to prenatal care providers. Patient influenza and Tdap vaccination acceptance rates were compared and predictors of vaccine acceptance were analyzed with bivariate logistic regression.ResultsOut of the 400 patient questionnaires distributed, 338 (84.5%) were completed and returned; 24 of 45 (53.3%) provider questionnaires were returned. Vaccination acceptance rates were 70.7% for the influenza vaccine and 76.3% for the Tdap vaccine. The logistic regression model indicated that predictors of acceptance for either vaccine in pregnancy are patient attitude and previous vaccination history. Patient attitudes were more favorable towards Tdap than influenza vaccination. The combination of healthcare provider recommendation and educational materials was significantly predictive of both Tdap and influenza vaccine acceptance. The most common reasons given for declining the influenza vaccine were safety concerns; the most common reasons given for declining the Tdap vaccine were that patients did not think it was required again when they received the vaccine before pregnancy.ConclusionsOur study suggests that providers can improve Tdap and influenza vaccination acceptance in pregnancy by recommending the vaccination in combination with provision of educational materials on the vaccines.     

Maternal Tdap vaccination: Coverage and acute safety outcomes in the vaccine safety datalink, 2007–2013

IntroductionSince October 2012, the combined tetanus toxoid, reduced diphtheria toxoid, acellular pertussis vaccine (Tdap) has been recommended in the United States during every pregnancy.MethodsIn this observational study from the Vaccine Safety Datalink, we describe receipt of Tdap during pregnancy among insured women with live births across seven health systems. Using a retrospective matched cohort, we evaluated risks for selected medically attended adverse events in pregnant women, occurring within 42 days of vaccination. Using a generalized estimating equation, we calculated adjusted incident rate ratios (AIRR).ResultsOur vaccine coverage cohort included 438,487 live births between January 1, 2007 and November 15, 2013. Across the coverage cohort, 14% received Tdap during pregnancy. By 2013, Tdap was administered during pregnancy in 41.7% of live births, primarily in the 3rd trimester. Our vaccine safety cohort included 53,885 vaccinated and 109,253 matched unvaccinated pregnant women. There was no increased risk for a composite outcome of medically attended acute adverse events within 3 days of vaccination. Similarly, across the safety cohort, over a 42 day window, incident neurologic events, thrombotic events, and new onset proteinuria did not differ by maternal receipt of Tdap. Among women receiving Tdap at 20 weeks gestation or later, as compared to their matched controls, there was no increased risk for gestational diabetes or cardiac events while venous thromboembolic events and thrombocytopenia were diagnosed within 42 days of vaccination at slightly decreased rates.ConclusionTdap coverage during pregnancy increased from 2007 through 2013, but was still below 50%. No acute maternal safety signals were detected in this large cohort.     

Persistence of antibodies 3 years after booster vaccination of adults with combined acellular pertussis, diphtheria and tetanus toxoids vaccine

The duration of protection after vaccination with reduced antigen content diphtheria, tetanus and acellular pertussis vaccines (Tdap) is not known. Long-term post-vaccination serological data will help to improve understanding of the duration of humoral immunity and guide vaccination policy for the timing of repeat dose administration. The persistence of antibodies to Tdap antigens was measured 3 years after vaccination of adults 19-64 years of age with one of 2 Tdap vaccines (Boostrix^®, GlaxoSmithKline Biologicals; Tdap-B: or Adacel^®, Sanofi Pasteur; Tdap-A). In both groups, geometric mean concentrations for antibodies to diphtheria, tetanus, and pertussis vaccine antigens were decreased at year 3 relative to levels observed 1 month and 1 year following vaccination, but remained higher than pre-vaccination levels. Seroprotection rates for diphtheria and tetanus remained high for both Tdap vaccines (for diphtheria, 96.9% and 97.8% for the Tdap-B and Tdap-A groups, respectively; for tetanus, 98.1% and 99.6%, respectively).     

Reactogenicity and immunogenicity of tetanus toxoid,reduced diphtheria toxoid,and acellular pertussis vaccine (Tdap) in pregnant and nonpregnant women

ObjectiveTetanus toxoid, reduced diphtheria toxoid, and acellular pertusiss (Tdap) vaccine is recommended during each pregnancy, regardless of prior receipt. Data on reactogenicity and immunogenicity, particularly after repeated Tdap, are limited. We compared local injection-site and systemic reactions and serologic response following Tdap in (1) pregnant and nonpregnant women and (2) pregnant women by self-reported prior Tdap receipt.Study designPregnant women (gestational age 20–34 weeks) and nonpregnant women receiving Tdap were enrolled in this observational study. Injection-site and systemic reactions were assessed for one week post-vaccination. Pertussis toxin, filamentous hemagglutinin, pertactin, fimbriae, tetanus and diphtheria specific IgG antibody titers were determined by standardized enzyme-linked immunosorbent assay at baseline and 28 days post-vaccination. Reactogenicity and serologic responses were compared by pregnancy status, and within pregnant women by self-reported prior Tdap receipt.Results374 pregnant and 225 nonpregnant women were vaccinated. Severe local or systemic reactions or “any” fever were uncommon (≤3% for both groups). Moderate/severe injection-site pain was significantly higher in pregnant (17.9%) versus nonpregnant (11.1%) women, but did not prompt a healthcare visit. Proportions of other moderate/severe or any severe reactions were not significantly higher in pregnant compared to nonpregnant women. Moderate/severe (including pain) and severe reactions were not significantly higher in pregnant women receiving repeat versus first-time Tdap. Antibody titers increased from baseline to post-vaccination for all vaccine antigens in pregnant and nonpregnant women; post-vaccination titers against pertussis toxin and filamentous hemagglutinin were significantly higher in nonpregnant versus pregnant women (p < 0.01).ConclusionTdap was well-tolerated in pregnant and nonpregnant women. Pregnant women were more likely to report moderate/severe pain at the Tdap injection-site compared with nonpregnant women, but did not necessitate medical visits. Prior Tdap receipt did not increase occurrence of moderate/severe local or systemic reactions in pregnant women. Serologic responses to all vaccine antigens were robust.Clinical Trial Registration@ClinicalTrials.gov. NCT02209623.https://clinicaltrials.gov/ct2/show/NCT02209623.     

Randomized study of immune responses to two Tdap vaccines among adolescents primed with DTaP and comparison with results among adolescents primed with DTwP

BackgroundIt has been reported that persons primed with acellular (DTaP) pertussis vaccines have reduced duration of pertussis protection compared with those primed with whole-cell (DTwP) vaccines. However, due to the rapid transition to acellular vaccines, studies attempting directly to compare protection among DTaP-primed vs DTwP-primed individuals are subject to confounding by age and other limitations of ecological studies. Using validated assay results and stored sera from multiple Tdap studies, we evaluated two licensed Tdap vaccines among DTaP-primed adolescents to allow comparison with results obtained in the same laboratory from earlier studies involving DTwP-primed adolescents.MethodsParticipants 11–12 years of age who had received exactly 5 doses of DTaP vaccine prior to 7 years of age were randomly assigned in 2012 to receive one of two licensed Tdap vaccines. Serum specimens obtained pre- and post-vaccination were assayed for responses to the vaccines. Current results were then compared to results obtained in the same laboratory from prior randomized Tdap studies conducted among adolescents primed with DTwP or DTaP.ResultsBoth Tdap vaccines produced strong antibody responses to diphtheria and tetanus; responses to contained pertussis antigens were consistent with the differing levels of those antigens in each Tdap vaccine. However, postvaccination pertussis antibody responses were as much as 71% lower in these DTaP-primed adolescents compared with responses among DTwP-primed adolescents in a prior study of the same two Tdap vaccines. In contrast, results from the present study were similar to those seen in another study of Tdap among DTaP-primed adolescents.DiscussionTaken together, these results from randomized clinical trials provide direct evidence of reduced antibody responses to both licensed Tdap vaccines among adolescents primed with DTaP vaccine, compared with adolescents primed with DTwP vaccine.Clinical trial registry number: ClinicalTrials.gov, NCT01629589.     

Effectiveness of a multimodal intervention to increase vaccination in obstetrics/gynecology settings

ObjectiveTo test the effectiveness of a multimodal intervention in obstetrics/gynecology (ob-gyn) clinics to increase uptake of influenza and tetanus-diphtheria-acellular pertussis (Tdap) vaccines in pregnant women and these vaccines plus human papillomavirus (HPV) vaccine in non-pregnant women.MethodsA cluster randomized controlled trial among 9 private ob-gyn practices in Colorado from 9/2011 to 5/2014. The intervention consisted of: designation of immunization champions, staff/provider trainings, assistance with vaccine purchasing/management, identification of eligible patients, standing order implementation, chart review/feedback, and patient education materials. Control practices continued usual care. Primary outcomes were receipt of influenza and Tdap vaccines among pregnant women and these vaccines plus HPV vaccine among non-pregnant women, comparing a Baseline period (Year 0/Year 1) to Year 2, intervention versus control. With an estimated sample size of 32,590 per arm, there would be >80% power to detect a 10% difference between groups.ResultsIn the Baseline period, 27% of pregnant women in both intervention and control practices received influenza vaccine. In Year 2, 29% of pregnant women in intervention practices received influenza vaccine versus 41% in control practices. In the Baseline period, 18% of pregnant women in intervention practices received Tdap vaccine versus 22% in control practices. Both intervention and control practices increased to 51% in Year 2, representing an increase of 33% for intervention practices and 29% for control practices, consistent with a change in Tdap recommendations. Relatively few HPV, influenza or Tdap vaccines (≤6% of eligible patients) were given to non-pregnant patients in either intervention or control practices at any time during the study.ConclusionIn this cluster randomized trial designed to increase vaccination uptake, both intervention and control practices showed improved vaccination of pregnant but not non-pregnant patients. Future work should focus on tailoring evidence-based immunization practices or developing new approaches to specifically fit busy ob-gyn offices.     

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

Persistence of antibodies following a single dose of Tdap vaccine (tetanus, diphtheria, and five-component acellular pertussis vaccine for use in individuals past childhood) was evaluated in a follow-up of adolescents (N=324) and adults (N=644) who had received Tdap in earlier clinical trials. Outcome measures were seroprotection (tetanus and diphtheria) or seropositivity (pertussis) and geometric mean titers. Humoral immune responses to all antigens were robust 1 month after initial immunization; antibodies exceeded pre-immunization levels 1, 3, and 5 years later. These data will contribute to selecting the optimal interval for booster doses of Tdap.     

Safety of tetanus,diphtheria, and acellular pertussis vaccination among pregnant active duty U.S. military women

BackgroundThe tetanus, diphtheria, and acellular pertussis (Tdap) vaccine was approved for U.S. adults in 2005 and recommended for administration in every pregnancy in 2012, with optimal timing between 27 and 36 weeks’ gestation. In the military, however, a current Tdap vaccination status is compulsory for service, and active duty women may be inadvertently exposed in early pregnancy. Safety data in this population are limited.ObjectivesTo assess safety of inadvertent (0–13 weeks’ gestation) and recommended (27–36 weeks’ gestation) exposure to the Tdap vaccine in pregnancy.MethodsPregnancies and live births from Department of Defense Birth and Infant Health Research program data were linked with military personnel immunization records to determine pregnancy Tdap vaccine exposure among active duty women, 2006–2014. Multivariable Cox and generalized linear regression models estimated associations between Tdap vaccine exposure and adverse pregnancy or infant outcomes.ResultsOf 145,883 pregnancies, 1272 were exposed to the Tdap vaccine in the first trimester and 9438 between 27 and 36 weeks’ gestation. Neither inadvertent nor recommended vaccine exposure were associated with spontaneous abortion, preeclampsia, or preterm labor. Among 117,724 live born infants, 984 were exposed to the Tdap vaccine in the first trimester and 9352 between 27 and 36 weeks’ gestation. First trimester exposure was not associated with birth defects, growth problems in utero, growth problems in infancy, preterm birth, or low birth weight. Tdap vaccine exposure between 27 and 36 weeks’ gestation was not associated with any adverse infant outcome.ConclusionsAmong a population of active duty women in the U.S. military who received the Tdap vaccine during pregnancy, we detected no increased risks for adverse maternal, fetal, or infant outcomes. Our findings corroborate existing literature on the safety of exposure to the Tdap vaccine in pregnancy.     

Notes from the field : use of tetanus, diphtheria, and pertussis vaccine (Tdap) in an Emergency Department - Arizona, 2009-2010

Because of an increasing incidence of reported pertussis cases attributed to waning immunity among adults and adolescents, the Advisory Committee on Immunization Practices (ACIP) in 2005 recommended administration of a new, combined tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) for adolescents and adults aged 11-64 years. ACIP recommended that they receive a single dose of Tdap to replace tetanus and diphtheria toxoid vaccine (Td) for booster immunization against tetanus and diphtheria if they had not previously received Tdap. Adults aged ≥65 years were to receive Td according to ACIP recommendations. To learn whether these age-specific recommendations were being followed in an emergency department (ED), the charts of a sample of patients receiving tetanus vaccines at a large ED were reviewed.     

Pertussis immunization in a high-risk postpartum population

We provided CDC recommended postpartum tetanus, diphtheria, acellular pertussis (Tdap) immunization to medically underserved, uninsured women in Houston through a standing order protocol. From January 7–April 30, 2008, 1129 of 1570 (72%) postpartum women (93% Hispanic; 11% ≤19 years) received Tdap before hospital discharge. Tdap uptake was 96.2% in women without self-reported contraindications. Recall of immunization history was inaccurate in 32% of unimmunized women who reported receiving antepartum immunization. Black women refused Tdap more often than other ethnicities (24% versus 8%; P = 0.003). Postpartum Tdap immunization was successfully implemented in a high-risk population through a standing order protocol. Barriers to postpartum immunization include inaccurate immunization history and the need for ongoing targeted education.     

Vaccine effectiveness of tetanus toxoid,reduced diphtheria toxoid,and acellular pertussis vaccine during a pertussis outbreak in Maine

BackgroundMultiple school-associated pertussis outbreaks were reported in Maine from 2010 to 2011. These outbreaks were associated with an overall increase in pertussis cases statewide. Waning of protection in students recently vaccinated with tetanus, diphtheria, and acellular pertussis (Tdap) has been implicated in the increase in reported rates of pertussis nationally.MethodsWe conducted a retrospective cohort study to evaluate Tdap vaccine effectiveness (VE) among students aged 11–19 years in two schools reporting outbreaks in 2011. All pertussis cases reported from August through November, 2011 at the two schools were included. Vaccination history was verified using provider information, state vaccine registry data, and parental verification. Attack rates (AR) were calculated. VE and duration of protection was calculated as VE = 1 − (AR_vaccinated/AR_unvaccinated) × 100% using a log binomial regression model.ResultsOf 416 students enrolled, 314 were included in the analyses. Twenty-nine cases collectively in Schools A and B. Tdap coverage was 65% at School A and 42% at School B before the start of the outbreak. Among students enrolled in the study, attack rates were 11.9% and 7.7% at Schools A and B, respectively. Overall VE was 68.5% (95% confidence interval (CI) 37.7–86.2). VE was 70.4% (95% CI 17.5–89.4) for School A and 65.2% (95% CI −19.2 to 89.9) for School B. VE <2 years versus ≥2 years from outbreak onset was not significantly different.ConclusionsTdap was moderately effective in preventing disease among vaccinated students. Vaccine coverage of 65% or less was suboptimal and might contribute to outbreaks. Waning VE was not demonstrated. Increased vaccination coverage rates as well as further evaluation of the role of acellular vaccine on VE is needed.