Effect of Dengue Serostatus on Dengue Vaccine Safety and Efficacy.

BACKGROUND: In efficacy trials of a tetravalent dengue vaccine (CYD-TDV), excess hospitalizations for dengue were observed among vaccine recipients 2 to 5 years of age. Precise risk estimates according to observed dengue serostatus could not be ascertained because of the limited numbers of samples collected at baseline. We developed a dengue anti-nonstructural protein 1 (NS1) IgG enzyme-linked immunosorbent assay and used samples from month 13 to infer serostatus for a post hoc analysis of safety and efficacy. METHODS: In a case-cohort study, we reanalyzed data from three efficacy trials. For the principal analyses, we used baseline serostatus determined on the basis of measured (when baseline values were available) or imputed (when baseline values were missing) titers from a 50% plaque-reduction neutralization test (PRNT50), with imputation conducted with the use of covariates that included the month 13 anti-NS1 assay results. The risk of hospitalization for virologically confirmed dengue (VCD), of severe VCD, and of symptomatic VCD according to dengue serostatus was estimated by weighted Cox regression and targeted minimum loss-based estimation. RESULTS: Among dengue-seronegative participants 2 to 16 years of age, the cumulative 5-year incidence of hospitalization for VCD was 3.06% among vaccine recipients and 1.87% among controls, with a hazard ratio (vaccine vs. control) through data cutoff of 1.75 (95% confidence interval [CI], 1.14 to 2.70). Among dengue-seronegative participants 9 to 16 years of age, the cumulative incidence of hospitalization for VCD was 1.57% among vaccine recipients and 1.09% among controls, with a hazard ratio of 1.41 (95% CI, 0.74 to 2.68). Similar trends toward a higher risk among seronegative vaccine recipients than among seronegative controls were also found for severe VCD. Among dengue-seropositive participants 2 to 16 years of age and those 9 to 16 years of age, the cumulative incidence of hospitalization for VCD was 0.75% and 0.38%, respectively, among vaccine recipients and 2.47% and 1.88% among controls, with hazard ratios of 0.32 (95% CI, 0.23 to 0.45) and 0.21 (95% CI, 0.14 to 0.31). The risk of severe VCD was also lower among seropositive vaccine recipients than among seropositive controls. CONCLUSIONS: CYD-TDV protected against severe VCD and hospitalization for VCD for 5 years in persons who had exposure to dengue before vaccination, and there was evidence of a higher risk of these outcomes in vaccinated persons who had not been exposed to dengue. (Funded by Sanofi Pasteur; ClinicalTrials.gov numbers, NCT00842530 , NCT01983553 , NCT01373281 , and NCT01374516 .).

Suitability of databases in the Asia-Pacific for collaborative monitoring of vaccine safety.

INTRODUCTION: Information regarding availability of electronic healthcare databases in the Asia-Pacific region is critical for planning vaccine safety assessments particularly, as COVID-19 vaccines are introduced. This study aimed to identify data sources in the region, potentially suitable for vaccine safety surveillance. This manuscript is endorsed by the International Society for Pharmacoepidemiology (ISPE). METHODS: Nineteen countries targeted for database reporting were identified using published country lists and review articles. Surveillance capacity was assessed using two surveys: a 9-item introductory survey and a 51-item full survey. Survey questions related to database characteristics, covariate and health outcome variables, vaccine exposure characteristics, access and governance, and dataset linkage capability. Other questions collated research/regulatory applications of the data and local publications detailing database use for research. RESULTS: Eleven databases containing vaccine-specific information were identified across 8 countries. Databases were largely national in coverage (8/11, 73%), encompassed all ages (9/11, 82%) with population size from 1.4 to 52 million persons. Vaccine exposure information varied particularly for standardized vaccine codes (5/11, 46%), brand (7/11, 64%) and manufacturer (5/11, 46%). Outcome data were integrated with vaccine data in 6 (55%) databases and available via linkage in 5 (46%) databases. Data approval processes varied, impacting on timeliness of data access. CONCLUSIONS: Variation in vaccine data availability, complexities in data access including, governance and data release approval procedures, together with requirement for data linkage for outcome information, all contribute to the challenges in building a distributed network for vaccine safety assessment in the Asia-Pacific and globally. Common data models (CDMs) may help expedite vaccine safety research across the region.

Background incidence rates of health outcomes of interest for COVID-19 vaccine safety monitoring in a US population: a claims database analysis.

OBJECTIVE: To evaluate background incidence rates of 59 health outcomes of interest (HOI) in a diverse population, including important subpopulations, during the pre-COVID-19 era (1 January 2017-31 December 2019) and the COVID-19 era (1 March 2020-31 December 2020), before the introduction of COVID-19 vaccines. DESIGN: Observational retrospective cohort study. Annual incidence rates and 95% confidence intervals (CIs) of HOIs were estimated for each population of interest, stratified by: age, sex, age and sex and seasonality. DATA SOURCE: Optum's de-identified Clinformatics Data Mart Database (CDM). PARTICIPANTS: Individuals from the US general population and four subgroups of interest: influenza-vaccinated, paediatric (<18 years of age), elderly (≥65 years of age) and pregnant women. RESULTS: During the COVID-19 era, the incidence of several cardiac conditions, coagulation disorders and acute liver injury increased across all populations assessed while the rates of some dermatological and neurological HOIs decreased relative to the pre-COVID-19 era. The incidence of acute respiratory distress syndrome (ARDS) varied considerably by subgroup: among the elderly, it decreased annually during the pre-COVID-19 era but peaked during the COVID-19 era; among pregnant women, it slightly increased annually during the pre-COVID-19 era and substantially increased during the COVID-19 era; among paediatrics, it decreased annually over the entire study. The incidence of the majority of HOIs increased with age, but were generally comparable between sexes with few exceptions. Cardiac, gastrointestinal, neurological and haematological HOIs, along with acute kidney injury and ARDS, were more common in males, whereas several immunological HOIs and chilblain-like lesions were more common in females. Pregnancy-related HOIs did not increase during the COVID-19 era, except for spontaneous abortions which increased annually over the entire study. CONCLUSION: These observations help contextualise fluctuations in background rates of adverse events noted during the COVID-19 era, and provide insight on how their use may impact safety surveillance for other vaccines.

Manufacturers' postmarketing safety surveillance of influenza vaccine exposure in pregnancy.

Pregnant women are at increased risk for hospitalization and death with influenza infection. The limited data on safety and effectiveness of influenza immunization in pregnancy emphasizes the importance of developing new and well-designed studies and of enhancing safety surveillance in pregnant women who are vaccinated with licensed influenza vaccines. Pregnancy exposure registries aim to collect and maintain data on the effects of marketed drugs and vaccines, when prescribed in pregnancy or during breastfeeding, on the women themselves and their children. Women who are prescribed a medication or vaccine as part of their routine clinical care can be enrolled directly or through reporting health care providers on a voluntary basis. Such registries generally are established for products that are intended for use by adolescents and adults and are a key component of the safety monitoring of licensed products. This article reviews some of the pregnancy registries that have been established for US-licensed vaccines, which includes influenza vaccines, and other postlicensure safety surveillance efforts for monitoring safety in vaccinated pregnant women.

Exposure to quadrivalent influenza vaccine during pregnancy: Results from a global pregnancy registry.

BACKGROUND: The Fluzone® Quadrivalent (IIV4, Sanofi Pasteur) Pregnancy Registry was created to monitor vaccine safety during pregnancy (clinicaltrials.gov, NCT01945424). Here, we describe maternal, pregnancy, obstetrical and neonatal outcomes after vaccine exposure in pregnant women between August 2013 and September 2019. METHODS: All women exposed to IIV4 during their pregnancy were eligible for inclusion. Outcomes were prospective (reported following vaccine exposure but before knowledge of pregnancy outcome ascertained through prenatal tests) or retrospective (prenatal tests were undertaken before the exposure was reported). RESULTS: Among 239 IIV4 vaccine exposure reports received, there were 105 prospective and 10 retrospective reports of maternal adverse events (AEs). The most frequent prospectively reported maternal AEs were medication errors (expired product [n = 8, 3.8%]; extra dose [n = 7, 3.3%]) and injection site pain (n = 7, 3.3%). Among 62 prospectively reported pregnancy and obstetrical events with available follow-up information, seven AEs were reported, four (6.4%) of which were spontaneous abortions. A further seven AEs were reported among the 29 retrospective pregnancy and obstetrical events with available follow-up information. Among neonatal outcomes (15 prospective; 28 retrospective), >85% were reported as full-term births. One premature birth was reported prospectively. Four other neonatal AEs were reported, all retrospectively: two cases of talipes (club foot), one central nervous system anomaly and one atrial septal defect. All infants with available information had normal APGAR scores at 5 minutes. CONCLUSIONS: The frequency of AEs following exposure to IIV4 during pregnancy did not indicate new safety concerns.

Yellow fever vaccine usage in the United States and risk of neurotropic and viscerotropic disease: A retrospective cohort study using three healthcare databases.

BACKGROUND: Yellow fever (YF) vaccines are highly effective and have a well-established safety profile despite the risk of rare serious adverse events (SAEs), vaccine-associated neurotropic (YEL-AND) and viscerotropic disease (YEL-AVD). This study aimed to describe US civilian YF vaccine usage, the population characteristics and pre-existing immunosuppressive medical conditions among those vaccinated, and to provide updated risk estimates of neurotropic and viscerotropic disease post-vaccination. METHODS: A retrospective cohort study was conducted using de-identified patient information from Optum Electronic Healthcare Record (EHR) (2007-2019), Optum Clinformatics Data Mart (CDM) (2004-2019) and IBM MarketScan (2007-2019) databases. YF vaccine recipients were identified using relevant vaccination and procedural codes. Demographic characteristics and pre-existing medical conditions were described. Incidence proportions with 95% confidence intervals (CI) of neurotropic and viscerotropic diseases occurring ≤ 30 days post-vaccination, after exclusion of unlikely cases based on current clinical guidelines of YEL-AND and YEL-AVD, were calculated. RESULTS: A total of 92,205, 46,539 and 125,235 YF vaccine recipients were retrieved from Optum EHR, Optum CDM and IBM MarketScan databases, respectively. The majority of vaccine recipients were aged < 60 years (highest proportion aged 18-29 years) with a higher proportion of females overall. Few vaccine recipients (<1%) had conditions predisposing them to immunosuppression. Four non-fatal cases of neurotropic disease and zero cases of viscerotropic disease were identified. The incidence proportion of post-vaccination neurotropic disease was 1.41 (95% CI: 0.15-6.61) and 3.04 (95% CI: 0.86-8.11) per 100,000 vaccine recipients in Optum EHR and IBM MarketScan, respectively, with no events identified in Optum CDM. CONCLUSIONS: This study provides updated insights into current YF vaccine usage in US civilian recipients and supports the safety profile of YF vaccines in US practice. The low frequency of pre-existing immunosuppressive medical conditions among vaccine recipients suggests good adherence to vaccination guidelines by healthcare practitioners. The risk of developing neurotropic and viscerotropic disease post-vaccination remains rare.

Safety and use of tetanus-diphtheria-acellular pertussis-5 (Tdap5) vaccine during pregnancy: findings from 11 years of reporting to a pregnancy registry.

The "Adacel (Tdap5) Pregnancy Registry" was used to identify 1182 women who received the tetanus, diphtheria, acellular pertussis [5 components] (Tdap5) vaccine during pregnancy from 2005 to 2016. To evaluate the safety and use of prenatal Tdap5, we calculated the rate of maternal, obstetrical, pregnancy and neonatal outcomes following Tdap5 pregnancy exposure and assessed vaccine uptake by year and trimester of exposure. The most commonly reported maternal adverse events included injection site reactions (2.6%; 95% Confidence Interval 1.8%, 3.7%), nervous system events (1.3%; 0.8%, 2.1%) and musculoskeletal events (1.1%; 0.6%, 1.9%). The most commonly reported complications of pregnancy were hypertension/preeclampsia (5.5%; 3.3%, 8.9%) and gestational diabetes (2.5%; 1.1%, 5.3%), while those for labor and delivery were premature labor (2.9%; 1.4%, 5.7%) and premature membrane rupture (1.5%; 0.4%, 3.8%). These rates were similar to, or lower than those reported for the general population of pregnant women. Among pregnancies with known birth outcomes (N = 275), 90.4% (86.2%, 93.4%) resulted in a live birth, 5.9% (3.6%, 9.5%) in spontaneous abortion, 3.0% (1.4%, 5.8%) in stillbirth, and 0.7% (0.0%, 2.8%) in ectopic pregnancies. Most newborns had normal APGAR scores and birth weights (98.1% and 93.0%, respectively), and only two reported a congenital anomaly (0.7%; 0.0%, 2.8%). An influx of reports in 2012 with third trimester Tdap5 exposure coincided with the 2012 updated Advisory Committee on Immunization Practices recommendations. This analysis did not identify any safety concerns across the continuum of maternal, obstetrical, pregnancy, and neonatal outcomes in women who received Tdap5 vaccination during pregnancy.

Why we need more collaboration in Europe to enhance post-marketing surveillance of vaccines.

The influenza A/H1N1 pandemic in 2009 taught us that the monitoring of vaccine benefits and risks in Europe had potential for improvement if different public and private stakeholders would collaborate better (public health institutes (PHIs), regulatory authorities, research institutes, vaccine manufacturers). The Innovative Medicines Initiative (IMI) subsequently issued a competitive call to establish a public-private partnership to build and test a novel system for monitoring vaccine benefits and risks in Europe. The ADVANCE project (Accelerated Development of Vaccine benefit-risk Collaboration in Europe) was created as a result. The objective of this paper is to describe the perspectives of key stakeholder groups of the ADVANCE consortium for vaccine benefit-risk monitoring and their views on how to build a European system addressing the needs and challenges of such monitoring. These perspectives and needs were assessed at the start of the ADVANCE project by the European Medicines Agency together with representatives of the main stakeholders in the field of vaccines within and outside the ADVANCE consortium (i.e. research institutes, public health institutes, medicines regulatory authorities, vaccine manufacturers, patient associations). Although all stakeholder representatives stated they conduct vaccine benefit-risk monitoring according to their own remit, needs and obligations, they are faced with similar challenges and needs for improved collaboration. A robust, rapid system yielding high-quality information on the benefits and risks of vaccines would therefore support their decision making. ADVANCE has developed such a system and has tested its performance in a series of proof of concept (POC) studies. The system, how it was used and the results from the POC studies are described in the papers in this supplementary issue.

Incidence rates of neurotropic-like and viscerotropic-like disease in three dengue-endemic countries: Mexico, Brazil, and Malaysia.

BACKGROUND: The background incidence of viscerotropic- (VLD) and neurotropic-like disease (NLD) unrelated to immunization in dengue-endemic countries is currently unknown. METHODS: This retrospective population-based analysis estimated crude and standardized incidences of VLD and NLD in twelve hospitals in Brazil (n = 3), Mexico (n = 3), and Malaysia (n = 6) over a 1-year period before the introduction of the tetravalent dengue vaccine. Catchment areas were estimated using publicly available population census information and administrative data. The denominator population for incidence rates was calculated, and sensitivity analyses assessed the impact of important assumptions. RESULTS: Total cases adjudicated as definite VLD were 5, 57, and 56 in Brazil, Mexico, and Malaysia, respectively. Total cases adjudicated as definite NLD were 103, 29, and 26 in Brazil, Mexico, and Malaysia, respectively. Crude incidence rates of cases adjudicated as definite VLD in Brazil, Mexico, and Malaysia were 1.17, 2.60, and 1.48 per 100,000 person-years, respectively. Crude incidence rates of cases adjudicated as definite NLD in Brazil, Mexico, and Malaysia were 4.45, 1.32, and 0.69 per 100,000 person-years, respectively. CONCLUSIONS: Background incidence estimates of VLD and NLD obtained in Mexico, Brazil, and Malaysia could provide context for cases occurring after the introduction of the tetravalent dengue vaccine.

Vaccine safety perceptions and experience with adverse events following immunization in Kazakhstan and Uzbekistan: a summary of key informant interviews and focus groups.

Few studies have examined vaccine safety attitudes in developing countries and countries in economic transition. The objectives of this study were to identify concerns about immunizations and strategies to address these concerns in Kazakhstan and Uzbekistan, two Central Asian countries in economic transition. Qualitative text analysis was conducted on 16 focus groups and 24 key informant interviews to identify discussion themes related to the study objectives. Specific areas of concern included: adverse events following immunizations, vaccine quality, healthcare worker competence, and lack of vaccine information available to parents. Focus group participants also suggested relevant topics and sources for informational materials.

Yellow fever vaccine: an updated assessment of advanced age as a risk factor for serious adverse events.

Since 1996, the scientific community has become aware of 14 reports of yellow fever vaccine (YEL)-associated viscerotropic disease (YEL-AVD) cases and four reports of YEL-associated neurotropic disease (YEL-AND) worldwide, changing our understanding of the risks of the vaccine. Based on 722 adverse event reports after YEL submitted to the U.S. Vaccine Adverse Event Reporting System in 1990-2002, we updated the estimates of the age-adjusted reporting rates of serious adverse events, YEL-AVD and YEL-AND. We found that the reporting rates of serious adverse events were significantly higher among vaccinees aged > or =60 years than among those 19-29 years of age (reporting rate ratio = 5.9, 95% CI 1.6-22.2). Yellow fever is a serious and potentially fatal disease. For elderly travelers, the risk for severe illness and death due to yellow fever infection should be balanced against the risk of a serious adverse event due to YEL.