A multisite study of pertussis vaccine effectiveness by time since last vaccine dose from three Canadian provinces: A Canadian Immunization Research Network study

BackgroundPertussis remains poorly controlled relative to other diseases targeted by childhood vaccination programs. We combined estimates from four population-based studies of pertussis vaccine effectiveness (VE) in three Canadian provinces using a meta-analytic approach to improve precision and explore regional variation in VE and durability of protection.MethodsStudies were conducted in Alberta, Manitoba, and Ontario over periods ranging from 1996 to 2015. Adjusted log odds ratios (OR; VE = 100*[1-OR]) of the effect of vaccination on pertussis risk were estimated by time since last vaccination in each study and pooled using DerSimonian and Laird random-effects models. We used the I² statistic to estimate between-study heterogeneity and assessed methodological and clinical heterogeneity through subgroup analyses of study design and age.ResultsData on 3,270 pertussis cases and 23,863 controls were available. Pertussis VE declined from 86% (95% CI 79%-90%, I² = 81.5%) at < 1 year since last vaccination to 51% (11%-74%, I² = 80.9%) by ≥ 8 years. Effect estimates were the most heterogeneous in the least and most elapsed time periods since last vaccine dose. This was attributable mostly to variation between provinces in the distribution of age groups and number of vaccine doses received within time periods, as well as study design and small numbers in the most elapsed time period.Interpretation: Consistent trends of decreasing pertussis VE with increasing time since last vaccination across three Canadian provinces indicate the need for immunization schedules and vaccine development to optimize protection for all individuals, especially for adolescents and young adults at greatest risk of infection.     

Effectiveness of pertussis vaccination in New South Wales,Australia, 1996-1998

Pertussis notifications have increased over the past decade in Australia and other industrialised countries. This study estimates the effectiveness of pertussis vaccination in one Australian State (New South Wales, NSW) among children aged less than 14 years, during a period when an Australian whole-cell pertussis vaccine was in routine use. Cases notified with pertussis between 1996 and 1998 and pertussis vaccine coverage estimates from the Australian Childhood Immunisation Register were used. Vaccine effectiveness (VE) was calculated using the screening method, with adjustment for age group, year of disease onset and area of residence. VE was highest (91%) in the youngest age group (8–23 months) and lowest (78%) in the oldest age group (9–13 years). Pertussis vaccination is highly effective at preventing pertussis in NSW children, as measured by notified cases. Ongoing monitoring will be important to evaluate VE following Australia's change to an acellular vaccine based program.     

Acellular pertussis vaccine effectiveness and waning immunity in Alberta,Canada: 2010–2015, a Canadian Immunization Research Network (CIRN) study

BackgroundPertussis is still frequently reported in Canada. In Alberta, pertussis incidence ranged from 1.8 to 20.5 cases per 100,000 persons for 2004–2015. Most cases occurred in those aged <15 years. In Alberta, acellular formulations replaced whole-cell in 1997. We investigated pertussis vaccine effectiveness (VE) using a test-negative design (TND) study.MethodsWe included all persons who had a real-time PCR laboratory test for Bordetella pertussis between January 1, 2010 and August 31, 2015, in the province of Alberta, Canada. Vaccination history was obtained from Alberta’s immunization repository. Vaccination status was classified as complete, incomplete, or unvaccinated, based on the province’s vaccination schedule. Persons who had received ≥one dose of whole cell vaccine were excluded from analysis. Multivariable logistic regression models were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) for pertussis infection by time since last vaccination. We adjusted for vaccination status, age, sex, neighbourhood income, urban/rural status, and the presence of a co-morbid condition. VE was calculated as [(1 − aOR) * 100].ResultsOf the 12,149 tests available, 936 (7.7%) were positive for Bordetella pertussis. Among the full cohort, VE was 90% (95% CI 87–92%) at 1 year, 81% (95% CI 77–85%) at 1–3 years, 76% (95% CI 68–82%) at 4–7 years, and 37% (95% CI 11–56%) at 8 or more years since a last dose of acellular pertussis vaccine.ConclusionsPertussis VE was highest in the first year after vaccination, then declined noticeably as years since a last vaccination increased. Our results suggest that a large number of adolescents and adults are susceptible to infection with Bordetella pertussis. Regular boosters throughout childhood, adolescence, and during pregnancy may be needed.     

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.     

A nested case-control study measuring pertussis vaccine effectiveness and duration of protection in Manitoba,Canada, 1992–2015: A Canadian Immunization Research Network Study

BackgroundPertussis persists in Manitoba despite the universal availability of pertussis vaccines. Recent cases have included previously vaccinated individuals, raising concerns about declining vaccine effectiveness (VE). We measured pertussis VE and duration of protection using Manitoba’s provincial immunization and communicable disease registries.MethodsUsing a nested case-control design, individuals with laboratory-confirmed pertussis in Manitoba diagnosed between April 1, 1992, and March 31, 2015, were matched to up to five population-based controls on age, gender, geography, and case physician or number of physician visits. Conditional logistic regression was used to estimate VE against pertussis for both the whole-cell (wP) and acellular (aP) pertussis vaccines. Duration of protection was assessed using time since last dose.ResultsData on 534 eligible cases and 2614 controls were available for analysis. The adjusted VE estimate for aP-containing vaccines was 85% (95%CI: 74–91%); VE was 89% (66–96%) one to three years after the last vaccination. The adjusted VE of wP-containing vaccines was –15% (–91–31%) during a large outbreak in 1994 and 1995 compared to 35% (–26–66%) during non-outbreak years.ConclusionsOur estimates suggest that the aP vaccine was effective in preventing pertussis since its introduction in Manitoba. VE was lower during a large outbreak, highlighting the importance of separately analyzing outbreak periods when estimating pertussis VE over time.     

Durability of protection after 5 doses of acellular pertussis vaccine among 5–9 year old children in King County,Washington

PurposeWaning of immunity after vaccination with the acellular Pertussis (aP) vaccine has been proposed as one of the main reasons for pertussis resurgence in the US. In this study, we estimated time-varying vaccine effectiveness after 5 doses of aP vaccine.MethodsWe conducted a retrospective cohort study among children 5–9 years old (born between 2008 and 2012) living in King County, Washington, USA, who participated in the Washington State Immunization Information System. We estimated time-varying vaccine effectiveness after 5 doses of aP using smoothed scaled Schoenfeld residuals obtained from fitting Cox proportional hazards models to the data as well as piecewise constant Poisson regression.ResultsThere were 55 pertussis cases in this cohort, of whom 22 (40%) were fully-vaccinated and 33 (60%) were under-vaccinated. Vaccine effectiveness (VE) remained high for up to 42 months after the fifth dose (VE(t) = 89%; 95% CI: 64%, 97%) as estimated using survival analysis methods and up to 4 years (VE(t) = 93%; 95% CI: 67%, 98%) as estimated using Poisson regression.ConclusionWe did not find evidence for waning of vaccine effectiveness for up to four years after 5 doses of aP among 5 –9 years old children in King County, WA.     

Effectiveness of maternal pertussis vaccination in Singapore: A test-negative case-control study

Pertussis vaccination (Tdap -Tetanus-diphtheria-acellular pertussis) for pregnant women has been recommended since November 2017 in Singapore. In this prospective test-negative case-control study from 2018 to 2019, we aimed to evaluate vaccine effectiveness (VE) against pertussis infection and pertussis-related intensive care unit (ICU) admission according to Tdap (Tetanus-diphtheria-acellular pertussis) during pregnancy and/or infant pertussis vaccination. A total of 58 children (26 cases, 32 controls) were recruited with 4 ICU admissions. The median age was 3 months (interquartile range [IQR] 1.50–4.56 months). Overall, 25.9 % of mothers had received antenatal Tdap vaccination and 43.1 % of infants received pertussis vaccination, majority only 1 dose. Tdap in pregnancy alone without infant vaccine or with 0–1 infant dose had a VE of 97.62 % (95 % confidence interval [CI] 53.25–99.88 %), 98.17 % (95 %CI 66.61–99.9 %) respectively, against pertussis infection and 71.9 % (95 %CI 0.0–98.64), 75.86 % (95 % CI 0.0–98.78) respectively, against ICU admissions. Conclusion: Maternal Tdap vaccination was highly protective against infant pertussis and should be routinely recommended for all pregnant women.     

Effectiveness of acellular pertussis vaccine and evolution of pertussis incidence in the community of Madrid from 1998 to 2015

IntroductionPertussis is a communicable disease that primarily affects infants. Vaccination has led to an important reduction in the incidence of the disease, however, resurgence of the disease has been observed. This study aimed to analyze the incidence of pertussis and assess the vaccination effectiveness (VE) of different schedules of acellular pertussis vaccination in the community of Madrid.MethodsPertussis cases notified to the Mandatory Disease Reporting System from 1998 to 2015 were analyzed. Five comparison periods were created: 1998–2001 (reference), 2002–2005, 2006–2009, 2010–2012 and 2013–2015. The incidence ratio (IR) between inter-epidemic periods was analyzed using a Poisson regression. VE was calculated using the screening method. Vaccine status data were collected from the vaccine registry.ResultsIn total, 3855 cases were notified. Inter-epidemic periods were observed every 3–4 years. The incidence increased (IR: 5.99, p < 0.05) in the 2013–2015 period, particularly among infants younger than 1 month (IR: 32.41, p < 0.05). Vaccination data were available in 89% of cases. For those receiving the last dose at ≤6-month VE was 89.9% (95% confidence interval (CI): 87.3–92.0) after one year of follow-up, and 85.5% (95% CI: 82.4–88.1) after 11 years of follow-up. For those receiving the last dose at 18-months VE decreased from 98.8% (95% CI: 98.3–99.1) to 85.1% (95% CI: 81.9–87.7) in the same period, and for those receiving the last dose at 4-year VE decreased from 99.6% (95% CI: 99.3–99.7) to 79.3% (95% CI: 74.6–83.1).ConclusionsB. pertussis is circulating in our population, as shown by the epidemic peaks and increased incidence of pertussis in recent years. VE increased with the number of doses and decreased with the follow-up period. The effect of this and other vaccination strategies must be monitored to control the disease.     

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.     

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.     

Dose-dependent effectiveness of acellular pertussis vaccine in infants: A population-based case-control study

BackgroundPertussis is a vaccine-preventable disease which is most severe in young infants. More than two decades after the introduction of acelluar pertussis vaccines (aPV) in national immunization programs in many countries worldwide, a resurgence of pertussis has been recognized. Suboptimal effectiveness of aPV has been blamed as one major reason but only few studies have evaluated dose-dependent vaccine effectiveness (VE) provided by aPV in current practice.MethodsWe performed a population-based retrospective case-control study by comparing pertussis immunization data of children 2.5 months to 2 years of age hospitalized for pertussis and residing in Switzerland with immunization data of a random control sample of children aged 2 years and residing in Switzerland. VE was defined as the percentage of hospitalizations avoided by number of aPV doses. It was calculated as 1-infection rate ratio (IRR)*100. IRR was calculated by dividing infection rates of vaccinated children and infection rates of unvaccinated children. To get dose specific VE, infection rates were stratified by number doses received.ResultsVE against hospitalization due to pertussis increased significantly with each consecutive aPV dose in a “3 + 1” primary course in infants: 42.1% (95% CI: 11.3–62.6), 83.9% (70.2–92.1), 98.2% (96.1–99.3), and 100% (97.9–100) after the 1st, 2nd, 3rd, and 4th dose, respectively.ConclusionAcellular pertussis vaccines continue to demonstrate protection against hospitalization due to pertussis in infants and young children. Therefore, together with advancing immunization of pregnant women and household contacts, better control of severe pertussis in young infants can be achieved by timely initiation of immunization.     

Meningococcal C conjugate vaccine effectiveness before and during an outbreak of invasive meningococcal disease due to Neisseria meningitidis serogroup C/cc11, Tuscany,Italy

IntroductionIn Tuscany, Italy, where a universal immunization program with monovalent meningococcal C conjugate vaccine (MCC) was introduced in 2005, an outbreak of invasive meningococcal disease (IMD) due to the hypervirulent strain of Neisseria meningitidis C/cc11 occurred in 2015–2016, leading to an immunization reactive campaign using either the tetravalent (ACWY) meningococcal conjugate or the MCC vaccine. During the outbreak, IMD serogroup C (MenC) cases were also reported among vaccinated individuals. This study aimed to characterize meningococcal C conjugate vaccines (MenC-vaccines) failures and to estimate their effectiveness since the introduction (2005–2016) and during the outbreak (2015–2016).MethodsMenC cases and related vaccine-failures were drawn from the National Surveillance System of Invasive Bacterial Disease (IBD) for the period 2006–2016. A retrospective cohort-study, including the Tuscany' population of the birth-cohorts 1994–2014, was carried out. Based on annual reports of vaccination, person-years of MenC-vaccines exposed and unexposed individuals were calculated by calendar-year, birth-cohort, and local health unit. Adjusted (by birth-cohort, local health unit, and calendar-year) risk-ratios (ARR) of MenC invasive disease for vaccinated vs unvaccinated were estimated by the Poisson model. Vaccine-effectiveness (VE) was estimated as: VE = 1-ARR.ResultsIn the period 2006–2016, 85 MenC-invasive disease cases were reported; 61 (71.8%) from 2015 to 2016. Twelve vaccine failures occurred, all of them during the outbreak. The time-interval from immunization to IMD onset was 20 days in one case, from 9 months to 3 years in six cases, and ≥7 years in five cases. VE was, 100% (95%CI not estimable, p = 0.03) before the outbreak (2006–2014) and 77% (95%CI 36–92, p < 0.01) during the outbreak; VE was 80% (95%CI 54–92, p < 0.01) during the overall period.ConclusionsIn Tuscany, MenC-vaccine failures occurred exclusively during the 2015–2016 outbreak. Most of them occurred several years after vaccination. VE during the outbreak-period was rather high supporting an effective protection induced by MenC-vaccines.     

Community awareness and predictors of uptake of pertussis booster vaccine in South Australian adults

ObjectivePertussis is a highly virulent vaccine preventable disease that remains a global challenge. This study aimed to assess community knowledge of pertussis infection as well as awareness and uptake of adult pertussis booster vaccine.MethodsA cross-sectional survey was conducted of randomly selected households in South Australia by Computer Assisted Telephone Interviews in 2011. Survey data were weighted to the age, gender and geographical area profile of the population.ResultsFrom 3124 randomly sampled contactable households, 1967 interviews were conducted (participation rate 63%) with individuals aged 18–93 years, including 608 parents of children aged <18 years. The majority of respondents (97%) had heard of pertussis (whooping cough) and 18% reported that a household member had previously contracted whooping cough infection. Most respondents considered whooping cough to be highly contagious (73%) and severe for infants (89%). Over half (51%) of those surveyed were aware that family members commonly transmit pertussis to infants. Despite high knowledge, pertussis vaccine uptake was low, with only 10% of respondents reporting pertussis vaccination in the previous five years. Whilst 61% of respondents were aware of the availability of an adult pertussis booster vaccine, only 8% (n = 154) reported their Family Physician had discussed it with them. If provided free, 77% agreed that they would be more likely to accept a booster pertussis vaccination. Independent predictors of recent pertussis vaccination included higher education, larger household size, perception of greater disease severity for infants and discussion with a Family Physician about pertussis vaccination.ConclusionsWhilst knowledge regarding transmission and severity of Bordetella pertussis was high, uptake of pertussis vaccination for adults is remarkably low amongst the South Australian community. Improved awareness regarding the availability of a booster pertussis vaccine through Family Physicians and/or provision of funded pertussis vaccination for adults has the potential to improve pertussis vaccine coverage.     

Effectiveness of parental cocooning as a vaccination strategy to prevent pertussis infection in infants: A case-control study

BackgroundDuring a pertussis epidemic in 2009, the Department of Health, Victoria, Australia, implemented a cocoon program offering parents of new babies a funded-dose of pertussis-containing vaccine. We assessed vaccine effectiveness (VE) of the program in reducing pertussis infection in infants.MethodsUsing a matched case-control design, infants aged <12 months that were notified with pertussis between 1 January 2010 and 31 December 2011, and born during the time that the cocoon program was in place, were identified. Controls were matched by area of residence and date of birth. Telephone interviews we conducted to ascertain parents’ vaccination status, and if vaccinated, timing of vaccination receipt relative to the birth of their baby. Odds ratios (ORs) were calculated for the association between vaccination and pertussis infection, with VE calculated as (1 – OR) × 100%.ResultsThe study recruited 215 cases and 240 controls (response rates 67% and 25% of eligible participants, respectively). Vaccination of both parents after delivery of the infant and ≥28 days prior to illness onset reduced pertussis infection by 77% (Vaccine Effectiveness [VE] = 77% (confidence interval [95% CI], 18–93%). After adjusting for maternal education, presence of a sibling within the household, and the infants’ primary course vaccination status, the adjusted VE was 64% (95% CI, −58–92%).ConclusionsAlthough not reaching statistical significance, our results demonstrated that cocoon immunisation – where both parents are vaccinated in the post-partum period – may offer some protection again infant pertussis infection. Cocoon immunisation could be considered in circumstances where antenatal vaccination of the mother has not occurred.     

Economic evaluation of an extended acellular pertussis vaccine programme for adolescents in Ontario, Canada

PURPOSE: Pertussis is a frequent cause of cough illness in adolescents. In Canada, until recently immunization against pertussis in public programmes has been restricted to children under the age of 7. The purpose of this analysis was to estimate the health and economic impact of an additional booster dose of the acellular vaccine in adolescents in Ontario. METHODS: We performed a cost effectiveness analysis, based on a predictive spreadsheet dynamic model following a cohort of 144,000 adolescents in Ontario from the age of 12 years over a 10-year-period from the Ontario Ministry of Health (MoH) and societal perspectives. The model was used to compare costs and benefits of a combined vaccination programme (CVP) including tetanus, diphtheria, and acellular pertussis (dTacp) administered at age 12, compared to current practice. RESULTS: From the MoH perspective, booster vaccination of dacpT at 12 years via the CVP would produce a yearly additional expected cost of CAD $0.52 per adolescent in Ontario with an incremental cost-effectiveness ratio of CAD $168 per pertussis case avoided based on a 10-year-period. If outcomes are discounted at 3%, the incremental cost-effectiveness ratio rises to $188/discounted pertussis case avoided. From the societal perspective, the CVP would be cost saving CAD $858,106 at 10 years for the cohort. Over the 10-year-period, more than 4400 cases of pertussis would be prevented with approximately 50 hospital admissions averted. CONCLUSIONS: This study suggests that administering a booster dose of dTacp at 12 years of age to replace diphtheria and tetanus vaccination at 14 years may reduce the economic burden of pertussis treatment in the long term at a reasonable cost.     

Effectiveness of Rubella vaccine in a rubella outbreak in Guangzhou city,China, 2014

BackgroundWHO recommends the use of rubella-containing vaccine (RCVs) to prevent rubella and congenital rubella syndrome (CRS). Most licensed rubella vaccines in use globally are based on RA27/3 strains and have estimated vaccine effectiveness (VE) rates of 95–100%. In contrast, China uses a BRD-II strain-based rubella vaccine. Few field studies have been conducted that estimate VE of China's RCV. On March 17, 2014, a rubella outbreak was reported in a middle school in Guangzhou city, China. We conducted an investigation to understand reasons for the outbreak, and we used that investigation to estimate vaccine effectiveness of China's rubella vaccine.MethodsTo identify cases, investigators reviewed records kept by the school doctor and absentee records kept by teachers. Self-administered questionnaires were sent to parents of all students to collect information about the students’ symptoms, the results of any physician consultation, and disease history. We obtained demographic information and illness information for all students in the school; vaccination status was determined by inspection of official, parent-held vaccination records. A retrospective cohort study was conducted in 13 classes that had secondary cases of rubella. Using the secondary attack rates, we evaluated VE by the number of RCV doses received and age at vaccination.ResultsDuring the period February 17–May 23, 2014, 162 students (50 suspected cases, 88 probable cases, 24 confirmed cases) were diagnosed with rubella, yielding an overall attack rate of 10% (162/1621). Cases occurred in 27 classes (73%) of 37 classrooms. Secondary cases occurred in 13 classes (35%) of 37 classrooms. A total of 1130 students (69.7%) have vaccination certificates; 419 (37%) students were record-confirmed to have received RCV. For those vaccinated using BRD-II strain vaccine, vaccine effectiveness (VE) was 94% (95%CI: 75–98). VE for measles, mumps, and rubella (MMR) vaccine which is based on either BRD-II or RA27/3 strain was 89% (95%CI: 56–97). VE of a single dose of domestic monovalent rubella vaccine that used BRD-II strain vaccine was 93% (95%CI: 73–98). VE for those who received the vaccine between 1 and 2 years of age was 95% (95% CI: 67–99) while the VE was 100% for those vaccinated after 2 years of age. VE among those who received RCV <12 years ago was 100% while VE among those who received RCV ≥12 years ago was 92% (95%CI: 70–98).ConclusionsThe rubella vaccines used in China that are based on the BRD-II rubella vaccine strain have VE of 94%, which is similar to the more commonly used RA27/3-based RCVs. Low vaccination coverage contributed to this outbreak; early reporting of an outbreak is necessary for effective outbreak response immunization.     

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.     

Influenza vaccine effectiveness in preventing hospitalization among Beijing residents in China, 2013–15

BackgroundEstimates of influenza vaccination effectiveness (VE) are valuable for populations where the vaccine has been promoted in order to support vaccination policy and to permit evaluation of vaccination strategies. Such studies would be important for China due to limited data available during seasons when the vaccine strains matched or mismatched the circulating viruses.MethodsWe conducted a test-negative study in hospitals in Beijing. Patients admitted to five hospitals in the city were enrolled during the winter influenza seasons of 2013–14 and 2014–15. Influenza virus infections were determined by PCR, and influenza vaccination records were extracted from a centralized electronic immunization registry. Influenza VE was estimated by logistic regression adjusting for age group, sex and chronic conditions, and matched by calendar week.ResultsA total of 2368 inpatients were recruited during the study period with a vaccination coverage in the control group of 12.8%. The overall estimate of influenza VE was 46.9% (95% CI: −20.4%, 76.6%) for the 2013–14 season and 5.0% (95% CI: −53.0%, 41.0%) for the 2014–15 season. Estimates of VE were relatively higher in children aged 6–17 years than older persons across two influenza seasons while estimates of VE for both adults and elderly were relatively low.ConclusionsOur findings were consistent with expected influenza vaccination effectiveness in seasons when the vaccine matched or mismatched circulating viruses. Strategies to increase influenza vaccine coverage could provide a public health benefit.     

Pertussis vaccine effectiveness in a frequency matched population-based case-control Canadian Immunization Research Network study in Ontario,Canada 2009–2015

Background

Resurgences of pertussis have occurred in several high-income countries, often linked to waning of immunity from acellular pertussis vaccines. The degree of waning observed has varied by study design and setting. In Ontario, pertussis has not shown a substantial resurgence in the past decade. The routine immunization schedule comprises three priming doses in infancy, toddler and pre-school doses, and an adolescent dose at 14–16?years of age.

Effectiveness of maternal pertussis vaccination in preventing infection and disease in infants: The NSW Public Health Network case-control study

BackgroundInfants are at the highest risk of severe complications – including death – as a result of pertussis infection. Controlling pertussis in this group has been challenging, particularly in those too young to be vaccinated. Following revised national recommendations in March 2015, the state of New South Wales, Australia, introduced a funded maternal vaccination campaign at 28 – 32 weeks of gestation using a 3-component tetanus-diphtheria-acellular pertussis vaccine (dTpa; Boostrix, GSK). This study aimed to assess the effectiveness of maternal vaccination and add to the growing body of evidence for this strategy.MethodsA 1:1 matched case-control study was conducted between 16 August 2015 and 17 August 2016. Cases were laboratory or doctor notified, laboratory confirmed (nucleic acid testing or culture) and aged <6 months at onset. Each control infant was randomly selected from public hospital births in the same geographical area in the period up to 3 days before and after the case’s birthdate. Odds ratios (OR) were calculated using conditional logistic regression. Vaccine effectiveness (VE) was calculated as 1 – OR.FindingsIn total, 117 cases and 117 controls were recruited. The overall VE estimate was non-significantly protective for infants <6 months old (VE 39%, 95% CI −12 to 66%). Higher VE was observed for infants <3 months old (VE 69%, 95% CI 13–89%) and against hospitalisation (VE 94%, 95% CI 59–99%).InterpretationMaternal pertussis vaccination with a 3-component acellular vaccine was found to be highly effective at preventing severe disease in infants, but was less effective at preventing disease which did not require hospitalisation. The overall VE reported in this study was lower than in prior studies and suggests that maternal vaccination, while an effective strategy at preventing severe pertussis, is less effective at protecting against infection or mild disease.