Impact and cost-effectiveness of a second tetanus toxoid,reduced diphtheria toxoid,and acellular pertussis (Tdap) vaccine dose to prevent pertussis in the United States

IntroductionThe United States experienced a substantial increase in reported pertussis cases over the last decade. Since 2005, persons 11 years and older have been routinely recommended to receive a single dose of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine. The objective of this analysis was to evaluate the potential impact and cost-effectiveness of recommending a second dose of Tdap.MethodsA static cohort model was used to calculate the epidemiologic and economic impact of adding a second dose of Tdap at age 16 or 21 years. Projected costs and outcomes were examined from a societal perspective over a 20-year period. Quality-adjusted Life Years (QALY) saved were calculated.ResultsUsing baseline pertussis incidence from the National Notifiable Diseases Surveillance System, Tdap revaccination at either age 16 or 21 years would reduce outpatient visits by 433 (5%) and 285 (4%), and hospitalization cases by 7 (7%) and 5 (5%), respectively. The costs per QALY saved with a second dose of Tdap were approximately US $19.7 million (16 years) and $26.2 million (21 years). In sensitivity analyses, incidence most influenced the model; as incidence increased, the costs per QALY decreased. To a lesser degree, initial vaccine effectiveness and waning of effectiveness also affected cost outcomes. Multivariate sensitivity analyses showed that under a set of optimistic assumptions, the cost per QALY saved would be approximately $163,361 (16 years) and $204,556 (21 years).ConclusionA second dose of Tdap resulted in a slight decrease in the number of cases and other outcomes, and that trend is more apparent when revaccinating at age 16 years than at age 21 years. Both revaccination strategies had high dollar per QALY saved even under optimistic assumptions in a multivariate sensitivity analysis.     

Universal tetanus,diphtheria, acellular pertussis (Tdap) vaccination of adults: What the Canadian public knows and wants to know

Tetanus, diphtheria, and acellular pertussis vaccine (Tdap) is recommended for all adults in Canada but uptake is low. This study measured the knowledge, attitudes, beliefs, and behaviors of Canadian adults to identify potential barriers and facilitators to Tdap uptake. A survey was undertaken on a geographically representative sample of Canadian adults (n = 4023) and 8 focus groups (62 participants) were conducted nationwide. The survey revealed that knowledge about pertussis and Tdap was low (38.3% correct answers). Only 36.0% of respondents reported being aware that all adults were recommended to receive Tdap and only 10.7% reported being immunized; 36.7% did not know whether they had received Tdap. Respondents who were aware of the immunization recommendations were twice as likely to be immunized (16.6% vs. 8.3%; p < 0.001). Only 9.3% believed that their health care provider thought that Tdap was important for adults. The focus group data supported the survey results. Participants wanted information about pertussis and Tdap communicated through multiple modalities, but a recommendation by their family physician was most important to their decision to be immunized or not. This study demonstrates that current recommendations for universal adult vaccination with Tdap are not reaching the general public in Canada and an alternative strategy will be required to improve Tdap vaccine uptake.     

Economic impact of implementing decennial tetanus toxoid,reduced diphtheria toxoid and acellular pertussis (Tdap) vaccination in adults in the United States

BackgroundIn the United States, persons ≥11 years are recommended to receive one dose of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine, followed by decennial tetanus- and diphtheria-toxoid (Td) boosters. Many providers use Tdap instead of Td. We evaluated epidemiologic and economic impacts of replacing Td boosters with Tdap.MethodsWe used a static cohort model to examine replacing Td with Tdap over the lifetime of 4,386,854 adults ≥21 years. Because pertussis is underdiagnosed and true incidence is unknown, we varied incidence from 2.5 cases/100,000 person-years to 500 cases/100,000 person-years. We calculated vaccine and medical costs from claims data. We estimated cost per case prevented and per quality-adjusted life year (QALY) saved; sensitivity analyses were conducted on vaccine effectiveness (VE), protection duration, vaccine cost, disease duration, hospitalization rates, productivity loss and missed work. We did not include programmatic advantages resulting from use of a single tetanus-toxoid containing vaccine.ResultsAt lowest incidence estimates, administering Tdap resulted in high costs per averted case ($111,540) and QALY saved ($8,972,848). As incidence increased, cases averted increased and cost per QALY saved decreased rapidly. With incidence estimates of 250 cases/100,000 person-years, cost per averted case and QALY saved were $984 and $81,678 respectively; at 500 cases/100,000 person-years, these values were $427 and $35,474. In multivariate sensitivity analyses, assuming 250 cases/100,000 person-years, estimated cost per QALY saved ranged from $971 (most favorable) to $217,370 (least favorable).ConclusionsOur findings suggest that replacing Td with Tdap for the decennial booster would result in high cost per QALY saved based on reported cases. However, programmatic considerations were not accounted for, and if pertussis incidence, which is incompletely measured, is assumed to be higher than reported through national surveillance, substituting Tdap for Td may lead to moderate decreases in pertussis cases and cost per QALY.     

Safety of tetanus,diphtheria, acellular pertussis (Tdap) vaccination during pregnancy

The objective of this study was to evaluate the safety of prenatal tetanus, diphtheria, acellular pertussis (Tdap) vaccination. This cohort study was conducted among pregnant members at Kaiser Permanente Southern California (KPSC). The exposed cohort consisted of women who received Tdap vaccine on or after the 27th week of pregnancy between January 2018 and January 2019. The unexposed cohort consisted of matched women who were pregnant between January 2012 and December 2014 and were not vaccinated with any Tdap vaccine throughout their pregnancy. Maternal and infant characteristics and pre-specified endpoints were collected through automated data and review of the electronic health records. Unadjusted and adjusted relative risks (aRRs) with confidence intervals (CIs) were estimated by Poisson regression. Non-inferiority testing (i.e., to rule out a two-fold increase) was conducted for primary endpoints with adjustment for multiplicity. Superiority testing was conducted without multiplicity adjustment for secondary endpoints. The analysis consisted of 16,606 pairs of Tdap recipients and unexposed pregnant women. For the primary endpoints, the aRR for preeclampsia/eclampsia was 1.38 (98.75% CI:1.21–1.58) and the aRR for intrauterine infection was 1.28 (98.75% CI:1.12–1.47). These increases were consistent with the background increasing trend of these diagnoses among all pregnant women at KPSC since 2011, and the upper limit of the 98.75% CI of both aRRs did not exceed the pre-specified threshold of 2. No increased risks of small for gestational age (aRR = 1.04, 98.75% CI:0.94–1.16) or preterm delivery (aRR = 0.71, 98.75% CI:0.64–0.78) were observed. No evidence of increased risks for secondary endpoints, including poor fetal growth, preterm pre-labor rupture of membranes, stillbirth/fetal death, placental abruption, transfusion during delivery hospitalization, and neonatal death, was observed. Prenatal Tdap vaccination after the 27th week of pregnancy was not associated with increased risks of pre-specified maternal and infant outcomes, supporting the safety of Tdap vaccination during pregnancy.     

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.     

Kinetics of maternal pertussis-specific antibodies in infants of mothers vaccinated with tetanus,diphtheria and acellular pertussis (Tdap) during pregnancy

BackgroundKinetics of Tdap-induced maternally-derived antibodies in infants are poorly understood. Pre-Tdap era data suggest that maternal pertussis antibodies in infants have a half-life of approximately 5–6 weeks.Methods34 mother-infant pairs had blood collected before maternal Tdap vaccination, 4 weeks later, at delivery (maternal and cord), and at infant ages 3 and 6 weeks from June 2014-March 2015. Immunoglobulin G (IgG) to pertussis toxin (PT), filamentous hemagglutinin (FHA), fimbrial proteins (FIM) and pertactin (PRN) was quantified by multiplex luminex assay (IU/ml). Geometric mean concentrations (GMCs) with 95% confidence intervals (C.I.) and half-life of pertussis antibodies were calculated.ResultsTdap was administered to 34 women (mean age 31.1 years) at mean gestation 30.7 weeks (28–32.7). Mean neonatal gestation was 39.1 weeks (36–41.1) and mean birthweight was 3379 g (2580–4584). Four weeks post-Tdap vaccination, maternal pertussis-specific IgG GMCs increased ≥4-fold in 59%, 41%, 29% and 44% of women for PT, FHA, FIM and PRN, respectively, and then waned. The transplacental transport ratio of pertussis antibodies was 1.35 for PT, 1.41 for FHA, 1.31 for FIM and 1.36 for PRN. Between birth and age 6 weeks, infant serum GMC for PT-specific IgG decreased from 55.1 IU/mL (38.6–78.6) to 21.1 IU/ml (14.7–30.2), and the proportion of infants with PT levels ≥10 IU/ml fell from 97% to 67%. Half-life of pertussis-specific IgG in infants in days was 29.4 (95% CI 27.3–31.7) for PT, 29.8 (95% CI 27.7–32.2) for FHA, 31.2 (95% CI 28.9–33.7) for PRN, and 35.8 (95% CI 30.1–44.3) for FIM.ConclusionThe half-life of pertussis-specific antibodies in infants induced by maternal Tdap vaccination (29–36 days) is shorter than previously reported. Understanding how the durability of passively-acquired antibodies impacts infant susceptibility to pertussis and response to primary vaccination is critical to refine prevention strategies.     

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.     

Adverse events after tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine administered to adults 65 years of age and older reported to the Vaccine Adverse Event Reporting System (VAERS), 2005-2010

Background

Tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine was not licensed for use in adults aged ≥65 years due to lack of sufficient efficacy and safety data.

Objective

To characterize reports to the Vaccine Adverse Event Reporting System (VAERS) among adults aged ≥65 years who received Tdap vaccine ‘off-label’ to assess for potential vaccine safety concerns.

Methods

We searched VAERS for US reports of adverse events (AEs) in subjects aged ≥65 years who received Tdap vaccine from 9/1/2005 to 9/08/2010. Medical records were requested for all reports coded as serious (death, hospitalization, prolonged hospitalization, permanent disability, life-threatening-illness). Proportional reporting ratio (PRR) was used to assess for higher proportionate reporting for AEs after Tdap compared with Td reports in subjects aged ≥65 years.

Results

VAERS received 243 reports following Tdap administered to persons aged ≥65 years. Eleven (4.5%) reports were serious, including two deaths. Most common AEs were local reactions in 100 (41.2%) reports. Seventy-eight (32.1%) reports contained coding terms that denoted inappropriate administration of vaccine. ‘Cough’ was the only term associated with disproportionately higher reporting after Tdap compared with Td. Six of seven Tdap reports containing the term ‘Cough’ were non-serious. Clinical review of serious reports identified no unusual patterns of AEs.

Conclusion

Our VAERS review of the ‘off-label’ use of Tdap vaccine in adults ≥65 years did not find any safety concerns that warrant further study. These data will provide useful baseline information to assist CDC and FDA with monitoring efforts as permissive recommendations for Tdap in older persons are adopted.     

Tetanus,diphtheria and acellular pertussis (Tdap) vaccination among healthcare personnel—United States, 2011

Background

Health-care personnel (HCP) are at risk for exposure to and possible transmission of vaccine-preventable diseases. Receiving recommended vaccines is an essential prevention practice for HCP to protect themselves and their patients. The tetanus, diphtheria and acellular pertussis vaccine (Tdap) was recommended by the Advisory Committee on Immunization Practices (ACIP) for HCP in 2006 for protection against pertussis. We assessed the recent compliance of U.S. HCP in receiving Tdap vaccination.

Methods

To estimate Tdap vaccination coverage among HCP, we analyzed data from the 2011 National Health Interview Survey (NHIS). Multivariable logistic regression and predictive marginal models were performed to identify factors independently associated with vaccination among HCP.

Results

Overall, Tdap vaccination coverage was 26.9% among HCP aged 18–64 years (95% confidence interval (CI) = 24.3%, 29.7%), which was significantly higher compared with non-HCP among the same age group (11.1%; 10.5–11.8%). Overall, vaccination coverage was significantly higher among physicians (41.5%) compared with nurses (36.5%) and other types of HCP (range 11.7–29.9%). Vaccination coverage was significantly higher among HCP aged 18–49 years compared with those 50–64 years (30.0% vs. 19.2%, respectively). Characteristics independently associated with an increased likelihood of Tdap vaccination among HCP were: younger age, higher education, living in the western United States, being hospitalized within past year, having a place for routine health care in clinic or health center, and receipt of influenza vaccination in the previous year. Marital status of widowed, divorced, or separated was independently associated with a decreased likelihood of Tdap vaccination among HCP.

Conclusions

By 2011, Tdap vaccination coverage was only 26.9% among HCP. Vaccination coverage varied widely by types of HCP and demographic characteristics. Emphasizing the benefits of HCP vaccination for staff and patients, providing vaccinations in the workplace and other non-traditional settings, and providing Tdap at no charge may help increase Tdap vaccination among HCP in all health-care settings.     

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.     

Seroprevalence of Bordetella pertussis antibodies and anti-pertussis antibody response after a single dose of reduced-antigen combined diphtheria,tetanus, and acellular pertussis vaccine (Tdap) in pregnant Thai women

BackgroundMaternal immunization with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) has recently been implemented to prevent infant pertussis. Tdap is still not routinely recommended in Thailand, and there are limited data to support or challenge this strategy.ObjectivesThe primary aim was to determine the seroprevalence of anti-pertussis toxin antibodies (anti-PT IgG) among pregnant Thai women. The secondary aims were to evaluate antibodies response after Tdap vaccination between seronegative and seropositive mothers and to compare the different antibody titers at delivery among seropositive mothers who received Tdap to those who received tetanus-diphtheria vaccine (Td).MethodsThis randomized clinical trial was conducted during April 2018 to April 2019 at Siriraj Hospital, Bangkok, Thailand. A total of 129 pregnant women were included. Paired blood samples for anti-PT IgG levels were obtained during the first antenatal visit and at delivery. A baseline cut-off value of <5 IU/ml indicated seronegativity. There were 29 exclusions from the original 129 enrollment. All seronegative participants (n = 69) received Tdap, while the seropositive group were randomized 1:1 to receive either Tdap (n = 18) or Td (n = 13) during 27–36 weeks’ gestation. The antibody levels from both sera were compared between groups.ResultsThe seroprevalence of maternal anti-PT IgG was 33.3% (43/129). There was no significant difference in the increment of antibody levels after Tdap vaccination between the seronegative and seropositive groups (30.2 vs. 42 IU/ml; p = 0.183). Among seropositive groups, all Tdap recipients had increased antibody titers at delivery, while all Td recipients showed waning of immunity throughout gestation. (42 IU/ml vs. −7.4 IU/ml; p < 0.001).ConclusionMost pregnant Thai women have seronegative against pertussis. Most seropositive mothers had initial low antibody titers and their immunity significantly decreased before delivery. Our findings highlight the need for universal pertussis immunization in pregnancy regardless of individual baseline immunity.     

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.     

Age-specific effectiveness following each dose of acellular pertussis vaccine among infants and children in New Zealand

BackgroundThough it is believed the switch from whole cell to acellular pertussis vaccine has contributed to the resurgence of pertussis disease, few studies have evaluated vaccine effectiveness (VE) and duration of protection provided by an acellular vaccine schedule including three primary doses but no toddler-age dose. We assessed this schedule in New Zealand (NZ), a setting with historically high rates of pertussis disease, and low but recently improved immunisation coverage. We further evaluated protection following the preschool-age booster dose.MethodsWe performed a nested case-control study using national-level healthcare data. Hospitalised and non-hospitalised pertussis was detected among children 6 weeks to 7 years of age between January 2006 and December 2013. The NZ National Immunisation Register provided vaccination status for cases and controls. Conditional logistic regression was used to calculate dose-specific VE with duration of immunity examined by stratifying VE into ages aligned with the immunisation schedule.ResultsVE against pertussis hospitalisation was 93% (95% confidence interval [CI]: 87, 96) following three doses among infants aged 5–11 months who received three compared to zero doses. This protection was sustained through children’s fourth birthdays (VE ⩾ 91%). VE against non-hospitalised pertussis was also sustained after three doses, from 86% (95% CI: 80, 90) among 5–11 month olds to 84% (95% CI: 80, 88) among 3-year-olds. Following the first booster dose at 4 years of age, the protective VE of 93% (95% CI: 90, 95) among 4-year-olds continued through 7 years of age (VE ⩾ 91%).ConclusionsWe found a high level of protection with no reduction in VE following both the primary course and the first booster dose. These findings support a 3-dose primary course of acellular vaccine with no booster dose until 4 years of age.     

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.     

Low tetanus,diphtheria and acellular pertussis (Tdap) vaccination coverage among HIV infected individuals in Austria

Current management guidelines of HIV infected adults include recommendation to immunization against common vaccine preventable diseases. This effort is hindered by the scarce knowledge regarding the immunization status of this especially vulnerable patient group. This study analyzed the serostatus for pertussis, diphtheria and tetanus of more than 700 HIV infected individuals residing in Austria. These individuals were representative for the Austrian HIV cohort regarding sex, age, transmission risk and HIV progression markers. Overall, 73.6% were on suppressive HAART, mean CD4 cell count was 603 c/μl. Seropositivity was 84% for diphtheria, 51% for tetanus and 1% for pertussis. Migrants had a lower chance of tetanus seropositivity (OR 0.30 (CI 0.21 to 0.43)). Increase in CDC classification were associated with increased diphtheria seropositivity (OR 1.42 (CI 1.02 to 1.98)) and a CD4 nadir < 200 c/μl was associated with increased pertussis seropositivity (OR 12.2, 95% CI 1.2 to 121). Importantly due to the well preserved immune status of nearly all participants vaccination would be feasible in the majority of the seronegative patients. In patients with a CD4 count > 200 c/μl, 95% lacked seroprotection to at least one of the antigens included in the triple vaccine Tdap and could be vaccinated. Thus, a proactive approach would largely reduce the number of patients at risk for these vaccine-preventable diseases.     

Comparison of inflation of third dose diphtheria tetanus pertussis (DTP3) administrative coverage to other vaccine antigens

Third dose diphtheria tetanus pertussis (DTP3) administrative coverage is a commonly used indicator for immunization program performance, although studies have demonstrated data quality issues with administrative DTP3 coverage. It is possible that administrative coverage for DTP3 may be inflated more than for other antigens. To examine this, theory, we compiled immunization coverage estimates from recent country surveys (n = 71) and paired these with corresponding administrative coverage estimates, by country and cohort year, for DTP3 and 4 other antigens. Median administrative coverage was higher than survey estimates of coverage for all antigens (median differences from 26 to 30%), however this difference was similar for DTP3 as for all other antigens. These findings were consistent when countries were stratified by income level and eligibility for Gavi funding. Our findings demonstrate that while country administrative coverage estimates tend to be higher than survey estimates, DTP3 administrative coverage is not inflated more than other antigens.     

Intention to accept pertussis vaccine among pregnant women in Karachi,Pakistan

BackgroundMaternal immunization against pertussis is a potential strategy to protect young infants from severe disease. We assessed factors associated with intention to accept pertussis vaccination among pregnant women in Karachi, Pakistan.MethodsWe conducted a cross-sectional survey between May and August 2013 in pregnant women who visited healthcare centers in urban slums of Karachi city. Women completed a survey examining socio-demographic factors, vaccination history, knowledge on pertussis disease, perception of vaccine recommendation sources, and potential influences on vaccine decision-making.ResultsOf the 283 participants, 259 (92%) provided their intention to either accept or decline pertussis vaccination. Eighty-three percent women were willing to accept the pertussis vaccine if offered during pregnancy. About half (53%) of the participants had ever heard of pertussis disease. Perceptions of pertussis vaccine efficacy, safety, and disease susceptibility were strongly associated with intention to accept pertussis vaccine (p < 0.01). Healthcare providers, Ministry of Health, and mass media were considered as highly reliable sources of vaccine recommendation and associated with intention to accept antenatal pertussis vaccination (p < 0.001). Healthcare provider recommendation was a common reason cited by respondents for pregnant women to accept antenatal pertussis vaccination (p = 0.0005). However, opinion of primary decision-makers in the family (husbands and in-laws) was a crucial reason cited by respondents for pregnant women to reject pertussis vaccination in pregnancy (p = 0.003).ConclusionAntenatal pertussis vaccination initiatives in South Asia should strongly consider inclusion of family members, healthcare providers, national health ministries, and mass media to help implement new vaccination programs.     

Estimates of pertussis vaccine effectiveness in United States air force pediatric dependents

BackgroundPertussis vaccination compliance is critical for reduction in the prevalence of disease; however, the current acellular pertussis vaccine may not provide sufficient protection from infection. This study examined acellular pertussis vaccine effectiveness (VE) for Air Force dependents less than 12 years of age.MethodsWe conducted a case-control study among Air Force pediatric dependents from 2011 to 2013, comparing cases with positive pertussis test results to controls who received the same lab tests with a negative result. Our study population was categorized by age group and vaccination status based on the Centers for Disease Control and Prevention recommended pertussis vaccination schedule. VE was calculated with respect to vaccination status and pertussis lab results.ResultsWe compared 27 pertussis laboratory positive cases with 974 pertussis laboratory negative controls, 2 months to <12 years old. Comparing completely vaccinated to non-vaccinated patients, the overall VE was 78.3% (95% confidence interval (CI): 48.6, 90.8; p < 0.001). VE was highest among those 15 months to <6 years old: 97.6% (95% CI: 78.5, 99.7; p < 0.001). Children 6 to <12 years old had the lowest VE: 48.5% (95% CI: −74.0, 84.7; p = 0.28). Comparing partially vaccinated patients to nonvaccinated patients yielded 64.2% (95% CI: −7.2, 88.1; p = 0.06) overall VE.ConclusionsAcellular pertussis vaccination was effective at preventing laboratory confirmed pertussis among our Air Force pediatric dependent population, with highest protection among completely vaccinated, young children. Older children received the lowest amount of protection. Partial vaccination had near significant protection. Our overall calculated pertussis VE corroborates other pertussis VE studies looking at similar age groups.     

Tolerability and antibody response in adolescents and adults revaccinated with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine adsorbed (Tdap) 4-5 years after a previous dose

Background

Although decennial adult boosters of tetanus and diphtheria toxoids are recommended in Canada and the United States, a second dose of pertussis vaccine is not currently recommended for adults.

Methods

This open-label, postmarketing, multicenter study evaluated the tolerability and immunogenicity of a second dose of an adult formulation of tetanus, diphtheria, and pertussis vaccine (Tdap) in adolescents and adults 5 years after a first dose.

Results

A total of 545 participants from previous Tdap vaccine studies, ranging in age from 15 to 69 years, participated in this study. Of these participants, 94.2% had at least one solicited adverse event after the booster dose such as injection-site erythema (28.6%), swelling (25.6%), or pain (87.6%) or a systemic adverse event such as myalgia (61.0%), headache (53.2%), malaise (38.2%), or fever (6.5%). These adverse events were slightly more frequent than after the initial dose. Postvaccination, 100% of participants had a tetanus antibody level ≥0.10 IU/mL and 95% had a diphtheria antibody level ≥0.10 IU/mL. For pertussis, 82.1% (pertussis toxoid), 96.7% (filamentous hemagglutinin), 95.6% (pertactin), and 99.8% (fimbriae) had a postvaccination antibody threshold of ≥50 EU/mL.

Conclusion

A second dose of Tdap vaccine 5 years after the initial dose was well tolerated and immunogenic in adolescents and adults.     

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.