Population-Based Study of Pertussis Incidence and Risk Factors among Persons >50 Years of Age, Australia

Despite vaccination programs, pertussis has been poorly controlled, especially among older adults in Australia. This longitudinal, retrospective, observational study aimed to estimate the incidence and risk factors of pertussis among persons ≥50 years of age in Australia in the primary care setting, including those with underlying chronic obstructive pulmonary disease (COPD) or asthma. We used the IQVIA general practitioner electronic medical record database to identify patients ≥50 years of age with a clinical diagnosis of pertussis during 2015-2019. Pertussis incidence rates ranged from 57.6 to 91.4 per 100,000 persons and were higher among women and highest in those 50-64 years of age. Patients with COPD or asthma had higher incidence rates and an increased risk for pertussis compared with the overall population ≥50 years of age. Our findings suggest that persons ≥50 years of age in Australia with COPD or asthma have a higher incidence of and risk for pertussis diagnosis.

Prospective, multi-center post-marketing surveillance cohort study to monitor the safety of the human papillomavirus-16/18 AS04-adjuvanted vaccine in Chinese girls and women aged 9 to 45 years, 2018-2020

Following the approval of Cervarix for the immunization of girls and women in China against high-risk human papillomavirus types 16 and 18, a non-interventional post-authorization safety study was performed. A multi-center prospective cohort study assessed safety following Cervarix vaccination of Chinese girls and women aged 9-45 years between 31 May 2018 and 3 December 2020. Adverse events following immunization (AEFIs), potential immune-mediated diseases (pIMDs), and pregnancy-related outcomes were collected up to 12 months from the third immunization or 24 months from the first immunization, whichever came first. Among 3,013 women who received 8,839 Cervarix doses, 167 (5.5%) reported ≥ 1 any AEFI, and 22 (0.7%) reported 40 serious AEFIs. During the 30 days after each dose, 147 women (4.9%) reported 211 medically attended AEFIs, including 3 serious AEFIs reported by 1 woman (0.03%). One woman reported a pIMD. Cervarix was inadvertently administered to 65 women (2.2%) within 60 days before conception or during pregnancy. Of these women, 34 (52.3%) gave birth to live infant(s) with no apparent congenital anomalies, and 1 (1.5%) woman gave birth to a live infant with a congenital anomaly. No serious AEFIs or pIMDs were considered to be related to the vaccination. In Chinese women aged 9-45 years, immunization with the Cervarix three-dose schedule was well tolerated. Overall, no safety concerns were identified, although rare adverse events may have been missed due to the study sample size.Clinical trial registration: NCT03438006.

Incidence and Healthcare Burden of Pertussis among Older Adults with and without Pre-Existing Chronic Obstructive Pulmonary Disease or Asthma in South Korea

A retrospective cohort study was conducted to examine trends in the incidence and burden of pertussis among adults ≥50 years in South Korea, with/without pre-existing chronic obstructive pulmonary disease (COPD) or asthma. The nationwide Health Insurance Review and Assessment Service (HIRA) database was used to identify patients ≥50 years diagnosed with pertussis (2009-2018). Mean annual incidence of pertussis per 100 000 persons and overall mean incidence rate ratios (IRR) were calculated for patients with pre-existing COPD or asthma versus those with neither. Incremental healthcare costs (all-cause and pertussis-related) and healthcare utilisation (number of outpatient visits, emergency room visits, and number and length of hospitalisations) up to 12 months after, compared to 3 months before pertussis diagnosis, were also measured for each group (matched on sex, age, and Charlson Comorbidity Index). Of 1011 pertussis cases, 175 had asthma, 96 had COPD (not mutually exclusive), and 796 had neither. Overall mean pertussis incidence was 2.5, 3.4, and 0.5 for adults with pre-existing COPD, asthma, and those with neither. IRR (95% confidence interval) of pertussis for adults with pre-existing COPD and asthma was 4.9 (4.0-‍6.1) and 6.7 (5.7-7.9). Both COPD-pertussis and asthma-pertussis groups had higher mean incremental all-cause costs and length of hospitalisations than the general-pertussis group 3 months following pertussis diagnosis. In conclusion, individuals ≥50 years in South Korea with pre-existing COPD or asthma were at an increased risk of being diagnosed with pertussis and had higher healthcare resource utilisation than those without these conditions.

Incidence of Cytomegalovirus Primary and Secondary Infection in Adolescent Girls: Results From a Prospective Study

Developing a vaccine to prevent congenital cytomegalovirus (CMV) infection and newborn disability requires an understanding of infection incidence. In a prospective cohort study of 363 adolescent girls (NCT01691820), CMV serostatus, primary infection, and secondary infection were determined in blood and urine samples collected at enrollment and every 4 months for 3 years. Baseline CMV seroprevalence was 58%. Primary infection occurred in 14.8% of seronegative girls. Among seropositive girls, 5.9% had ≥4-fold increase in anti-CMV antibody, and 23.9% shed CMV DNA in urine. Our findings provide insights on infection epidemiology and highlight the need for more standardized markers of secondary infection.

Effectiveness of maternal immunisation with a three-component acellular pertussis vaccine at preventing pertussis in infants in the United States: Post-hoc analysis of a case-control study using Bayesian dynamic borrowing

BACKGROUND

Immunisation during pregnancy with a tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine can protect infants against pertussis between birth and paediatric vaccination. We aimed to estimate the vaccine effectiveness (VE) of third-trimester pregnancy immunisation with the three-component acellular pertussis (Td3ap) vaccine at preventing pertussis in infants <2 months in the United States (US), to support a label update.

METHODS

We performed a post-hoc sub-analysis of a case-control study conducted in six US Emerging Infections Program Network states between 2011 and 2014. Our analysis included only cases and controls whose mothers were either vaccinated with Td3ap or did not receive any Tdap vaccine. The association between Td3ap maternal immunisation and pertussis in infants was assessed for US data using a frequentist method with conditional logistic regression. A robustified analysis was conducted using Bayesian dynamic borrowing of non-US data, considering a mixing-weighted prior of 90% for historical non-US VE data, and of 10% for a vague prior. VE was estimated as (1-odds ratio) × 100%. Sensitivity analyses accounting for the impact of each non-US study, different mixing weights and missing/ambiguous data were performed.

RESULTS

We included 108 cases and 183 controls. Based on US data, the estimated VE of third-trimester maternal immunisation with Td3ap at preventing pertussis in infants <2 months was 78.0% (95% confidence interval: -38.0; 96.5). VE estimated by Bayesian dynamic borrowing of non-US data (with a 90% weight for historical data) was 83.4% (95% credible interval: 55.7; 92.5); sensitivity analyses produced similar VE estimates.

CONCLUSIONS

Effectiveness of third-trimester pregnancy immunisation with Td3ap at preventing infant pertussis in the US is very likely to be ≥ 50% and is most likely ∼ 80%. Bayesian dynamic borrowing of non-US VE data allowed overcoming the limited power (due to small sample size) of a brand-specific sub-analysis by considering additional evidence.

Risk Factors of Pertussis Among Older Adults in South Korea: A Nationwide Health Data-Based Case-Control Study

INTRODUCTION

To better understand the conditions associated with pertussis diagnosis among older adults in South Korea, a matched case-control study was conducted of individuals ≥ 50 years diagnosed with pertussis between 2009 and 2018.

METHODS

Pertussis cases were identified using the nationwide Health Insurance Review and Assessment service (HIRA) database. Each case was then matched to up to 10 controls identified using the National Health Insurance Service-National Sample Cohort (NHIS-NSC) by age, sex, and geographic region at index date. In the 12 months and 30 days prior to index date, the presence of clinical characteristics previously reported to be related to pertussis and pertussis-like conditions were assessed, respectively. A conditional multivariate logistic regression model was then used to calculate odds ratios (ORs) of pertussis diagnosis, adjusted for each of the characteristics.

RESULTS

Pertussis cases (n = 1004) generally demonstrated a higher prevalence of comorbidities compared to controls (n = 9710). Pre-existing asthma and chronic obstructive pulmonary disease (COPD) within 12 months of index date were associated with a two-fold increased risk of pertussis with adjusted ORs (95% confidence interval) of 2.08 (1.68-2.58) and 2.32 (1.59-3.39), respectively. Gastroesophageal reflux disease [GERD; 2.67 (2.23-3.19)], cancer [1.68 (1.23-2.31)], cardiovascular disease [1.62 (1.31-2.00)], renal disease [1.56 (1.12-2.16)], autoimmune disease [1.50 (1.25-1.79)], and hyperlipidemia [1.43 (1.16-1.77)] were also associated with pertussis diagnosis. Finally, acute respiratory events within 30 days prior to index date, such as pneumonia, acute bronchitis, and upper respiratory tract infection (URTI), were highly associated with increased odds of pertussis diagnosis [adjusted ORs of 8.28 (5.10-13.44), 4.86 (3.84-6.14), and 2.90 (2.30-3.67), respectively].

CONCLUSIONS

This study's findings complement and expand upon previous studies on the adult pertussis population, generating real-world data to describe underlying clinical characteristics of those diagnosed with pertussis in South Korea.

Investigating Tetanus, Diphtheria, Acellular Pertussis Vaccination During Pregnancy and Risk of Congenital Anomalies

INTRODUCTION

This observational retrospective matched cohort study evaluated the safety of a prenatal tetanus, diphtheria, acellular pertussis (Tdap) vaccination, Boostrix. We previously reported on the risk of maternal and neonatal outcomes; here we report on the risk of congenital anomalies in infants at birth through 6 months of age.

METHODS

The study included pregnant Kaiser Permanente Southern California members. Women who received the Tdap vaccine on or after the 27th week of pregnancy between January 2018 and January 2019 were matched to women who were pregnant between January 2012 and December 2014 and were not vaccinated with Tdap during pregnancy. Unadjusted and adjusted relative risks (aRRs) with 95% confidence intervals were estimated by Poisson regression. Quantitative secular trend analyses, from 2011 to 2017, were conducted on congenital anomalies with a statistically significant aRR > 1.

RESULTS

The analysis consisted of 16,350 and 16,088 live-born infants in the Tdap-exposed and unexposed cohorts, respectively. Of the 14 congenital anomaly body systems evaluated, 8 (eye, ear/face/neck, respiratory, upper gastrointestinal, genital, renal, musculoskeletal, integument) had statistically significant elevated aRRs, with point estimates ranging from 1.17 to 2.02. The observed elevated aRRs were consistent with their respective secular increases over time.

CONCLUSION

Cautious interpretation of these findings is warranted as these increases may have resulted from improved identification and diagnosis. Furthermore, the biological plausibility of an association between maternal vaccine exposure in the third trimester of pregnancy and birth defects is low. The overall study findings support the safety of maternal immunization with Boostrix during the third trimester of pregnancy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT03463577.

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.

Assessing the burden of dengue among household members in Alaminos, Laguna, the Philippines: a prospective cohort study

Background

The incidence of dengue is increasing rapidly and is a challenging health issue in the Philippines. Epidemiological data are largely based on a passive-surveillance reporting system, which leads to substantial under-reporting of cases.

Objectives

To estimate dengue infection and disease incidence prospectively at the community level in an endemic area of the Philippines using an active surveillance strategy.

Methods

We implemented active surveillance in the highly endemic community of Alaminos, Laguna. The study consisted of a 1-year follow-up with 2 visits scheduled at the start and end of the study, as well as regular active surveillance in between and unscheduled visits for suspected cases. Blood samples were collected and analyzed to detect dengue during the first scheduled visit and all unscheduled visits, and clinical examination was performed at all visits (registered at clinicaltrials.gov NCT02766088).

Results

We enrolled 500 participants, aged from 6 months to 50 years; 76.2% were found positive for immunoglobulin G (95% confidence interval [CI], 71.9-80.0), with 92.0% among those aged 9-17 years. Active (weekly) surveillance identified 4 virologically confirmed cases of dengue (incidence proportion 0.8; 95% CI 0.3-2.1); all in participants aged ≤14 years.

Conclusions

Routine surveillance programs such as sentinel sites are needed to characterize the entire clinical spectrum of symptomatic dengue, disease incidence, and transmission in the community.

Incidence of dengue illness in Mexican people aged 6 months to 50 years old: A prospective cohort study conducted in Jalisco

Background and objectives

The burden of dengue virus (DENV), a mosquito-borne pathogen, remains difficult to assess due to misdiagnosis and underreporting. Moreover, the large proportion of asymptomatic dengue cases impairs comprehensive assessment of its epidemiology even where effective surveillance systems are in place. We conducted a prospective community-based study to assess the incidence of symptomatic dengue cases in Zapopan and neighboring municipalities in the state of Jalisco, Mexico.

Methods

Healthy subjects aged 6 months to 50 years living in households located in the Zapopan and neighboring municipalities were enrolled for a 24-month follow-up study (NCT02766088). Serostatus was determined at enrolment and weekly contacts were conducted via phone calls and home visits. Participants had to report any febrile episode lasting for at least two days. Suspected dengue cases were tested by reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR), detection of non-structural protein 1 (NS1), anti-DENV immunoglobulin G and M (IgG and IgM) assays.

Results

A total of 350 individuals from 87 households were enrolled. The overall seroprevalence of anti-DENV IgG at enrolment was 19.4% (95% confidence interval [CI] 14.5–25.6) with the highest seroprevalence rate observed in the adult group. Over the 27-month study period from July 2016 to September 2018, a total of 18 suspected dengue cases were reported. Four cases were confirmed by RT-qPCR and serotyped as DENV-1. A fifth case was confirmed by the NS1 assay. The 13 remaining suspected cases were tested negative by these assays. Based on the 5 virologically confirmed cases, symptomatic dengue incidence proportion of 1.4% (95%CI 0.5–3.8) was estimated. No severe cases or hospitalizations occurred during the study.

Conclusion

Community-based active surveillance was shown as efficient to detect symptomatic dengue cases.

Clinical trial registration

NCT02766088.

A prospective, multicentre, cohort study to assess the incidence of dengue illness in households from selected communities in Brazil (2014-2018)

OBJECTIVES

To estimate the incidence of dengue infection across geographically distinct areas of Brazil.

METHODS

This prospective, household-based, cohort study enrolled participants in five areas and followed them up for up to 4 years (2014-2018). Dengue seroprevalence was assessed at each scheduled visit. Suspected dengue cases were identified through enhanced passive and active surveillance. Acute symptomatic dengue infection was confirmed through reverse-transcriptase quantitative polymerase chain reaction in combination with an antigenic assay (non-structural protein 1) and serology.

RESULTS

Among 3300 participants enrolled, baseline seroprevalence was 76.2%, although only 23.3% of participants reported a history of dengue. Of 1284 suspected symptomatic dengue cases detected, 50 (3.9%) were laboratory-confirmed. Based on 8166.5 person-years (PY) of follow-up, the incidence of laboratory-confirmed symptomatic infection (primary endpoint) was 6.1 per 1000 PY (95% confidence interval [CI]: 4.5, 8.1). Incidence varied substantially in different years (1.8-7.4 per 1000 PY). The incidence of inapparent primary dengue infection was substantially higher: 41.7 per 1000 PY (95% CI: 31.1, 54.6).

CONCLUSIONS

Our findings, highlighting that the incidence of dengue infection is underestimated in Brazil, will inform the design and implementation of future dengue vaccine trials.

CLINICAL TRIAL REGISTRATION

NCT01751139.

Hepatitis A antibody persistence 8 and 10 years after 1-dose and 2-dose vaccination in children from Panama

BACKGROUND

Hepatitis A virus (HAV) remains a global public health concern, which is potentially growing in Latin America, due to an expected shift from high to intermediate endemicity levels. The use of HAV vaccines in pediatric national immunization programs (NIPs), either as a 2-dose or a 1-dose schedule, has been explored in Latin American countries; however, evidence demonstrating long-term protection in this population is limited in the region. We evaluated long-term antibody persistence following a 1-dose partial series and the recommended 2-dose schedule used in Panama's pediatric NIP.

METHODS

Two independent cross-sectional serological surveys were conducted at year 8 (Y8) and Y10 following vaccination under the NIP with 1 or 2 doses of an inactivated HAV vaccine (Havrix, GSK). Seropositivity (anti-HAV antibody concentration ≥ 15 mIU/mL) rates and antibody geometric mean concentrations (GMCs) were assessed at each serosurvey. Non-inferiority of 1 dose versus 2 doses was also explored.

RESULTS

This study (NCT02712359) included 600 and 599 children at Y8 and Y10 post-vaccination, respectively. Seropositivity rates were 74.3% (95% confidence interval [CI]: 69.0; 79.2) and 97.7% (95% CI: 95.3; 99.1) at Y8 and 71.9% (95% CI: 66.4; 76.9) and 96.3% (95% CI: 93.5; 98.2) at Y10, in the 1-dose and 2-dose groups, respectively. Antibody GMCs were lower in the 1-dose versus the 2-dose group in both surveys. Non-inferiority was not demonstrated since the lower limit of the 2-sided 95% CI for the between-group difference in seropositivity rates (1-dose minus 2-dose) was < -10%.

CONCLUSION

Anti-HAV antibody persistence was observed in lower percentages of children receiving 1 dose versus 2 doses of Havrix, at 8 and 10 years post-vaccination in Panama. Further investigations are needed to confirm antibody persistence and conclude on the protection afforded beyond 10 years in the pediatric population in Latin America.

A systematic review of the burden of pertussis disease in infants and the effectiveness of maternal immunization against pertussis

Introduction Infants too young to be fully immunized are the most vulnerable to severe pertussis disease. To close this susceptibility gap, passive infant immunization through vaccination of pregnant women against pertussis was first introduced in 2011 in the United States and has been extended since then to more than 40 countries. Areas covered We conducted two systematic literature searches to describe the worldwide burden of pertussis disease in infants <6 months of age since 2005, and the effectiveness and impact of maternal pertussis vaccination in preventing infant pertussis since 2011. Expert opinion Pertussis disease incidence rates in infants aged <2-3 months were substantial in all countries with available data, exceeding 1000 cases per 100,000 population during outbreaks. Virtually all pertussis deaths occurred in this age group. Data from Africa, Eastern Mediterranean, and Asia were limited, but suggest a similar or higher disease burden than in Europe or the Americas. Estimates of effectiveness of second/third trimester pertussis vaccination in preventing pertussis disease in <2-3 months old infants were consistently high (69%-93%) across the observational studies reviewed, conducted in various settings with different designs. Maternal vaccination programs appear to be achieving their goal of reducing the burden of disease in very young infants. Plain language summary What is the context? Pertussis, also known as whooping cough, is a highly contagious disease of the respiratory tract. Infants too young to be fully vaccinated are at the highest risk of severe pertussis disease, hospitalization, and death. Vaccinating pregnant women against pertussis with a Tdap vaccine is recommended in more than 40 countries as a safe and effective strategy to protect infants for the first months of life. What is new? This review summarizes recent literature describing the burden of pertussis disease in infants worldwide prior to the introduction of maternal vaccination programs; pertussis disease incidence rates in infants aged <2-3 months were substantial in all countries with available data, exceeding 1000 cases per 100,000 population during outbreaks. Immunization of pregnant women with a Tdap vaccine can prevent about 70-90% of pertussis disease and up to 90.5% of pertussis hospitalizations in infants under 3 months of age. What is the impact? Limited available data suggest that incidence rates of pertussis disease after the introduction of Tdap maternal immunization have declined in infants. Current knowledge supports the implementation of Tdap maternal immunization programs.

Dengue Infection in Children in Fortaleza, Brazil: A 3-Year School-Based Prospective Cohort Study

Dengue is endemic in Brazil. The dengue surveillance system's reliance on passive reporting may underestimate disease incidence and cannot detect asymptomatic/pauci-symptomatic cases. In this 3-year prospective cohort study (NCT01391819) in 5- to 13-year-old children from nine schools in Fortaleza (N = 2,117), we assessed dengue virus (DENV) infection seroprevalence by IgG indirect ELISA at yearly visits and disease incidence through active and enhanced passive surveillance. Real-time quantitative polymerase chain reaction (RT-qPCR) and DENV IgM/IgG capture ELISA were used for diagnosis. We further characterized confirmed and probable cases with a plaque reduction neutralization test. At enrollment, 54.1% (95% CI: 46.6, 61.4) of children were DENV IgG positive. The annual incidence of laboratory-confirmed symptomatic dengue cases was 11.0 (95% CI: 7.3, 14.7), 18.1 (10.4, 25.7), and 10.2 (0.7, 19.7), and of laboratory-confirmed or probable dengue cases with neutralizing antibody profile evocative of dengue exposure was 13.2 (6.6, 19.9), 18.7 (5.3, 32.2), and 8.4 (2.4, 19.2) per 1,000 child-years in 2012, 2013, and 2014, respectively. By RT-qPCR, we identified 14 DENV-4 cases in 2012-2013 and seven DENV-1 cases in 2014. During the course of the study, 32.8% of dengue-naive children experienced a primary infection. Primary inapparent dengue infection was detected in 20.3% (95% CI: 13.6, 29.1) of dengue-naive children in 2012, 8.7% (6.9, 10.9) in 2013, and 5.1% (4.4, 6.0) in 2014. Our results confirmed the high dengue endemicity in Fortaleza, with active and enhanced passive surveillance detecting three to five times more cases than the National System of Disease Notification.

Meta-analysis of the risk of autoimmune thyroiditis, Guillain-Barré syndrome, and inflammatory bowel disease following vaccination with AS04-adjuvanted human papillomavirus 16/18 vaccine

Purpose

To assess the risk of three autoimmune diseases ‐ autoimmune thyroiditis (AIT), Guillain‐Barré syndrome (GBS), and inflammatory bowel disease (IBD) ‐ in females following AS04‐HPV‐16/18 vaccination.

Methods

This meta‐analysis included data from 18 randomized controlled trials, one cluster‐randomized trial, two large observational retrospective cohort studies, and one case‐control study. Following vaccination, a risk window of 2 years was defined for AIT and IBD and 42 days for GBS. Odds ratios (ORs) were estimated using three methods: meta‐analysis inverse‐variance with continuity correction (primary analysis), pooled estimate, and beta‐binomial regression.

Results

In all studies apart from the case‐control study, 154 398 exposed and 1 504 322 non‐exposed subjects were included, among whom there were 141 and 1972 cases of (autoimmune) thyroiditis; 2 and 2 cases of GBS; and 43 and 401 cases of IBD, respectively. In the case‐control study, there were 97 cases of AIT and 13 of GBS; matched with 802 and 130 controls, respectively. The primary analysis OR estimates were 1.46 (95% confidence interval [CI] 1.22‐1.76), 11.14 (2.00‐61.92), and 1.11 (0.75‐1.66) for (autoimmune) thyroiditis, GBS, and IBD, respectively.

Conclusions

This meta‐analysis did not show an increased risk of IBD following vaccination with AS04‐HPV‐16/18. The 1.5‐fold increased risk of (autoimmune) thyroiditis does not allow us to conclude about a causal association. For GBS, the very low number of cases and wide 95% CIs negate any firm conclusion.

Immune interference (blunting) in the context of maternal immunization with Tdap-containing vaccines: is it a class effect?

INTRODUCTION

Maternal immunization with reduced antigen content tetanus-diphtheria-acellular pertussis (Tdap)-containing vaccines has been recommended to prevent infant pertussis. However, maternal antibodies may interfere with infant responses to routine immunization with diphtheria-tetanus-acellular pertussis (DTaP)-containing vaccines, raising concerns of suboptimal protection after infant vaccination. We performed a narrative literature review to assess whether blunting occurs regardless of the manufacturer of maternal and infant vaccines. Because internationally agreed correlates of protection are lacking, the clinical significance of blunting is not yet fully understood. We have reviewed the evidence available to date.

AREAS COVERED

Thirteen studies that evaluated blunting after maternal immunization and infant primary/booster series were identified. Blunting was observed with various combinations of Tdap- and DTaP-containing vaccines for maternal and pediatric immunization. Studies assessing the effectiveness of maternal Tdap immunization beyond the primary infant immunization series in England and in the United States suggested no evidence of a clinically relevant blunting effect so far.

EXPERT COMMENTARY

This review indicates that the phenomenon of blunting does not depend on the manufacturer/brand of the pertussis-containing vaccines used for immunizing mothers or children. Currently, there is no epidemiological evidence that children whose mothers received Tdap are at increased risk of pertussis after pediatric vaccinations, although longer follow-up is required.

Prevalence and Persistence of Maternal Dengue Neutralizing Antibodies in Infants From Central and Southern Thailand: A Retrospective Cohort Study

Understanding maternal dengue virus (DENV) neutralizing antibody kinetics in infants remains timely to develop a safe and effective childhood immunization. This retrospective study evaluated the prevalence and persistence of maternal antibody titers against DENV serotypes 1 to 4 in 139 Thai infants at 2, 6, and 7 months of age, using serum samples collected in a vaccination trial ( http://clinicaltrials.gov ; NCT00197275). Neutralizing antibodies against all 4 DENV serotypes were detected in 87.8% and 22.9% of infants at 2 and 7 months, respectively. At 2 months, DENV-4 neutralizing antibody geometric mean titers were notably lower (80) compared with DENV-1 to DENV-3 (277-471). Our results corroborate previous findings that DENV-1 to DENV-4 maternal antibodies persist at 7 months despite titers decrease from 2 months onwards. As persisting maternal antibodies may inhibit immune responses in DENV-vaccinated infants, a comprehensive understanding of DENV antibody kinetics is required in the perspective of vaccine development for infants.

Introducing new vaccines in low- and middle-income countries: challenges and approaches

INTRODUCTION

The number of new vaccine introductions (NVIs) in low and middle-income countries (LMICs) has markedly increased since 2010, raising challenges to often overstretched and underfunded health care systems.

AREAS COVERED

We present an overview of some of these challenges, focusing on programmatic decisions, delivery strategy, information and communication, pharmacovigilance and post-licensure evaluation. We also highlight field-based initiatives that may facilitate NVI.

EXPERT COMMENTARY

Some new vaccines targeting populations other than infants require alternative delivery strategies. NVIs impact upon existing supply chain management, in particular vaccines with novel characteristics. A lack of understanding about immunization and misconceptions may be detrimental to NVI, as well as insufficient or poorly trained health care workforce. Many barriers exist to achieving good vaccination coverage. Real-world evaluation of vaccine safety, effectiveness and impact in LMICs may be limited by lack of robust demographic and disease epidemiology data, as well as limited health care and surveillance infrastructure. A thorough planning phase is crucial to define the most suitable delivery strategy based on the vaccine's and country's specificities. A communication plan and social mobilization are essential. Implementation research and innovative approaches applied to logistics, delivery, communication and program evaluation can facilitate NVI.

Biased efficacy estimates in phase-III dengue vaccine trials due to heterogeneous exposure and differential detectability of primary infections across trial arms

Vaccine efficacy (VE) estimates are crucial for assessing the suitability of dengue vaccine candidates for public health implementation, but efficacy trials are subject to a known bias to estimate VE toward the null if heterogeneous exposure is not accounted for in the analysis of trial data. In light of many well-characterized sources of heterogeneity in dengue virus (DENV) transmission, our goal was to estimate the potential magnitude of this bias in VE estimates for a hypothetical dengue vaccine. To ensure that we realistically modeled heterogeneous exposure, we simulated city-wide DENV transmission and vaccine trial protocols using an agent-based model calibrated with entomological and epidemiological data from long-term field studies in Iquitos, Peru. By simulating a vaccine with a true VE of 0.8 in 1,000 replicate trials each designed to attain 90% power, we found that conventional methods underestimated VE by as much as 21% due to heterogeneous exposure. Accounting for the number of exposures in the vaccine and placebo arms eliminated this bias completely, and the more realistic option of including a frailty term to model exposure as a random effect reduced this bias partially. We also discovered a distinct bias in VE estimates away from the null due to lower detectability of primary DENV infections among seronegative individuals in the vaccinated group. This difference in detectability resulted from our assumption that primary infections in vaccinees who are seronegative at baseline resemble secondary infections, which experience a shorter window of detectable viremia due to a quicker immune response. This resulted in an artefactual finding that VE estimates for the seronegative group were approximately 1% greater than for the seropositive group. Simulation models of vaccine trials that account for these factors can be used to anticipate the extent of bias in field trials and to aid in their interpretation.

Incidence and prevalence of hepatitis B in patients with diabetes mellitus in the UK: A population-based cohort study using the UK Clinical Practice Research Datalink

We assessed the incidence and prevalence of hepatitis B (Hep B) in patients with or without diabetes mellitus (DM) using the UK Clinical Practice Research Datalink (CPRD). This was a retrospective, observational study of diabetic and nondiabetic cohorts aged 0-80 years using CPRD (NCT02324218). Incidence rates (IR) for each cohort were calculated. Crude and adjusted (Poisson regression) IR ratios (IRR) were estimated with 95% confidence intervals (CI) to compare the cohorts. Hep B prevalence stratified by age, and hospitalization related to Hep B was also calculated. Of 7 712 043 subjects identified, 4 839 770 were included (DM: 160 760; non-DM: 4 679 010). Mean ages were 54.4 and 32.0 years, and 57.20% and 50.14% were male in the diabetic and nondiabetic cohorts, respectively. Hep B was identified in 29 diabetic and 845 nondiabetic subjects; IR was 4.03 per 100 000 person-years and 2.88 per 100 000 person-years, respectively. The adjusted IRR was 1.00 (95% CI: 0.70-1.50) between diabetic and nondiabetic cohorts. Hep B prevalence was higher in the diabetic cohort (0.01%-0.26%) than in the nondiabetic cohort (0.00%-0.03%) across the different age groups. Hep B-associated hospitalization IR was higher in the diabetic cohort (4.98-10.91) than the nondiabetic cohort (0.26-2.44). The Hep B IR, hospitalization and prevalence were higher in males in both cohorts. In conclusion, the risk of incident Hep B diagnosis in the diabetic cohort was not different from that in the nondiabetic cohort. However, prevalence of Hep B and Hep B-associated hospitalization rate was higher in the diabetic than in the nondiabetic cohort.

Incidence and costs of herpes zoster and postherpetic neuralgia in German adults aged ≥50 years: A prospective study

OBJECTIVES

Herpes zoster (HZ) mainly affects elderly people and immunocompromised individuals. HZ is usually characterized by a unilateral painful skin rash. Its most common complication, postherpetic neuralgia (PHN), may cause chronic debilitating pain. This study aimed to estimate the HZ incidence in individuals aged ≥50 years in Germany, the proportion of PHN and the economic burden.

METHODS

From 2010 to 2014, HZ patients were recruited when consulting physicians in physician networks covering about 157,000 persons aged ≥50 years. PHN was defined as "worst pain" rated ≥3 on the zoster brief pain inventory persisting or appearing over 90 days after rash onset. Costs were calculated based on medical resource utilization and lost working time.

RESULTS

HZ incidence was estimated as 6.7/1000 person-years, increasing with age to 9.4/1000 in ≥80 year-olds. Among 513 HZ patients enrolled, the proportion of PHN was 11.9%, rising with age to 14.3% in HZ patients ≥80 years. Estimated total cost per HZ patient was €156 from the healthcare system perspective and €311 from the societal perspective.

CONCLUSIONS

The study confirmed previous findings that HZ causes a substantial clinical and economic burden in older German adults. It also confirmed the age-related increasing risk of HZ and PHN.

Modeling the hepatitis A epidemiological transition in Brazil and Mexico

Background: Many low- to middle-income countries have completed or are in the process of transitioning from high or intermediate to low endemicity for hepatitis A virus (HAV). Because the risk of severe hepatitis A disease increases with age at infection, decreased incidence that leaves older children and adults susceptible to HAV infection may actually increase the population-level burden of disease from HAV. Mathematical models can be helpful for projecting future epidemiological profiles for HAV.

Methods: An age-specific deterministic, dynamic compartmental transmission model with stratification by setting (rural versus urban) was calibrated with country-specific data on demography, urbanization, and seroprevalence of anti-HAV antibodies. HAV transmission was modeled as a function of setting-specific access to safe water. The model was then used to project various HAV-related epidemiological outcomes in Brazil and in Mexico from 1950 to 2050.

Results: The projected epidemiological outcomes were qualitatively similar in the 2 countries. The age at the midpoint of population immunity (AMPI) increased considerably and the mean age of symptomatic HAV cases shifted from childhood to early adulthood. The projected overall incidence rate of HAV infections decreased by about two thirds as safe water access improved. However, the incidence rate of symptomatic HAV infections remained roughly the same over the projection period. The incidence rates of HAV infections (all and symptomatic alone) were projected to become similar in rural and urban settings in the next decades.

Conclusion: This model featuring population age structure, urbanization and access to safe water as key contributors to the epidemiological transition for HAV was previously validated with data from Thailand and fits equally well with data from Latin American countries. Assuming no introduction of a vaccination program over the projection period, both Brazil and Mexico were projected to experience a continued decrease in HAV incidence rates without any substantial decrease in the incidence rates of symptomatic HAV infections.

A dynamic transmission model with age-dependent infectiousness and reactivation for cytomegalovirus in the United States: Potential impact of vaccination strategies on congenital infection

We present an age-structured dynamic transmission model for cytomegalovirus (CMV) in the United States, based on natural history and available data, primarily aiming to combine the available qualitative and quantitative knowledge toward more complex modeling frameworks to better reflect the underlying biology and epidemiology of the CMV infection. The model structure explicitly accounts for primary infections, reactivations and re-infections. Duration of infectiousness and likelihood of reactivation were both assumed to be age-dependent, and natural reduction in the re-infection risk following primary infection was included. We used an empirical social contact matrix (POLYMOD-based) as support for CMV transmission between different age groups. The baseline model reproduced well the age-stratified seroprevalence data (National Health and Nutrition Examination Survey III) used for calibration. The model was further used to explore the potential impact of hypothetical vaccination on reducing congenital CMV infection under various vaccine profiles and vaccination scenarios. Our preliminary model-based simulations suggested that while infant vaccination may represent an attractive way to reduce congenital CMV infection over time, adolescent female vaccination with an adequate routine booster platform may, under certain conditions, provide an alternative. However, for such tools to be considered toward actual decision-making, enhanced validations based on additional studies and data would be further necessary. The modeling framework presented in this paper was designed to be sufficiently general and flexible, such that it can allow for further adaptations to reflect new knowledge or data that may become available in the future.

Incidence and risk factors of herpes zoster among hiv-positive patients in the german competence network for HIV/AIDS (KompNet): a cohort study analysis

Background

HIV infection is a risk factor for the development of Herpes zoster (HZ) and its complications. Prior to antiretroviral therapy (ART), HZ incidence in HIV-infected individuals ranged from 2.9–5.1/100 person-years. There is limited evidence for the impact of ART on HZ occurrence among HIV-infected adults. We analysed the incidence of, and risk factors for, HZ in a large cohort of German HIV-positive patients.

Methods

The study population was taken from the German KompNet cohort, a nationwide multicenter HIV cohort study. The study population was defined by age (≥ 18 years), year of first positive HIV diagnosis, CD4 values ± 6 months from HIV diagnosis (t₀), and month of HZ diagnosis. Incidences were estimated using a Poisson distribution, and uni- and multivariate Cox proportional Hazard ratio (HR) regression models were fitted to identify risk factors for developing an initial HZ episode. Independent variables were sex, age at HIV diagnosis, route of HIV transmission, ART status, CD4 count before HZ episode, immunosuppressive medication, and mode of data documentation (retrospective or prospective).

Results

HZ incidence in the overall study population was 1.2/100 person-years. In a subset of patients for that we were able to examine risk factors the following was observed: We examined 3,757 individuals whose mean age at t₀ was 38 years. Of those individuals, 96% were diagnosed with HIV in 1996 or later, with a mean observation time of 5.8 years. HZ episodes (n = 362) were recorded in 326 patients (8.7%), resulting in annual HZ incidences of 1.7/100 person-years overall, and 1.6/100 person-years for initial HZ cases. The main risk factors associated with an initial HZ episode were: not partaking in ART compared with an ART regimen containing a non-nucleoside reverse-transcriptase inhibitor (HR 0.530, p < 0.001) or a protease inhibitor (HR 0.624, p = 0.004); and lower CD4 count by 100 cells/μl (HR 0.918, p=0.001).

Conclusions

HZ incidence was 4-11-fold higher than in non HIV-infected individuals, but in our study HZ incidences were lower than in previous studies relating to HIV-positive patients. We showed that ART is an important protective factor for HZ episodes.

A risk-based sampling plan for monitoring of histamine in fish products

In 2008, the French Institute for Public Health Surveillance reported an increase in the number of histamine food poisoning outbreaks and cases in France. The aim of this study was to propose a new monitoring plan for characterizing consumers' exposure to histamine through fishery products. As fish products of concern are numerous, we proposed that the number of samples allocated for a fish category be chosen based on the risk associated with the category. Point risk estimates of histamine poisoning were assessed with the Risk Ranger tool. Fresh fish with high histidine content was found to contribute most to the number of cases. The (estimated) risks associated with the consumption of canned and deep-frozen fish appear marginal as compared with the risk associated with fresh fish with high histidine concentrations. Accordingly, we recommend excluding canned and deep-frozen fish from the monitoring plan, although these risk estimates can be biased. Within a category, samples were proportional to the relative food consumption of the different fishes. The spatial and seasonal consumption patterns were also taken into account for the design of the new monitoring plan. By testing appropriate numbers of samples from categories of fish products of concern, this plan will permit investigation of trends or comparison of product categories presenting risks of histamine poisoning.