The COVID-19 vaccine development: A pandemic paradigm

COVID-19 pandemic has resulted in millions of deaths and a social-economic crisis. A worldwide effort was made to develop efficient vaccines for this disease. A vaccine should produce immune responses with specific and neutralizing antibodies, and without harmful effects such as the antibody-dependent enhancement that may be associated with severe acute respiratory syndrome. Vaccine design involves the selection of platforms that includes viral, viral-vector, protein, nucleic acid, or trained immunity-based strategies. Its development initiates at a pre-clinical stage, followed by clinical trials when successful. Only if clinical trials show no significant evidence of safety concerns, vaccines can be manufactured, stored, and distributed to immunize the population. So far, regulatory authorities from many countries have approved nine vaccines with phase 3 results. In the current pandemic, a paradigm for the COVID-19 vaccine development has arisen, as many challenges must be overcome. Mass-production and cold-chain storage to immunize large human populations should be feasible and fast, and a combination of different vaccines may boost logistics and immunization. In silico trials is an emerging and innovative field that can be applied to predict and simulate immune, molecular, clinical, and epidemiological outcomes of vaccines to refine, reduce, and partially replace steps in vaccine development. Vaccine-resistant variants of SARS-CoV-2 might emerge, leading to the necessity of updates. A globally fair vaccine distribution system must prevail over vaccine nationalism for the world to return to its pre-pandemic status.

U.S. Population-Based background incidence rates of medical conditions for use in safety assessment of COVID-19 vaccines

The Coronavirus Disease 2019 (COVID-19) pandemic has had a devastating impact on global health, and has resulted in an unprecedented, international collaborative effort to develop vaccines to control the outbreak, protect human lives, and avoid further social and economic disruption. Mass vaccination campaigns are underway in multiple countries and are expected worldwide once more vaccine becomes available. Some early candidate vaccines use novel platforms, such as mRNA encapsulated in lipid nanoparticles, and relatively new platforms, such as replication-deficient viral vectors. While these new vaccine platforms hold promise, limited safety data in humans are available. Serious health outcomes linked to vaccinations are rare, and some outcomes may occur incidentally in the vaccinated population. Knowledge of background incidence rates of these medical conditions is a critical component of vaccine safety monitoring to aid in the assessment of adverse events temporally associated with vaccination and to put these events into context with what would be expected due to chance alone. A list of 22 potential adverse events of special interest (AESI), including neurologic, autoimmune, and cardiovascular disorders, was compiled by subject matter experts at the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention. The most recently available U.S. background rates for these medical conditions, overall and by age, sex, and race/ethnicity (when available), were sourced from reported statistics (data published by medical panels/ associations or federal government reports), and literature reviews in PubMed. This review provides estimates of background incidence rates for medical conditions that may be monitored or studied as AESI during safety surveillance and research for COVID-19 vaccines and other new vaccines.

Review the safety of Covid-19 mRNA vaccines: a review

The novel coronavirus disease 2019 (COVID-19) has infected more than 100 million people globally within the first year of the pandemic. With a death toll surpassing 500,000 in the United States alone, containing the pandemic is predicated on achieving herd immunity on a global scale. This implies that at least 70-80 % of the population must achieve active immunity against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), either as a result of a previous COVID-19 infection or by vaccination against SARS-CoV-2. In December 2020, the first two vaccines were approved by the FDA through emergency use authorization in the United States. These vaccines are based on the mRNA vaccine platform and were developed by Pfizer/BioNTech and Moderna. Published safety and efficacy trials reported high efficacy rates of 94-95 % after two interval doses, in conjunction with limited side effects and a low rate of adverse reactions. The rapid pace of vaccine development and the uncertainty of potential long-term adverse effects raised some level of hesitation against mRNA vaccines in the global community. A successful vaccination campaign is contingent on widespread access to the vaccine under appropriate storage conditions, deployment of a sufficient number of vaccinators, and the willingness of the population to be vaccinated. Thus, it is important to clarify the objective data related to vaccine safety, including known side effects and potential adverse reactions. The present review was designed to provide an update on the current state of science related to the safety and efficacy of SARS-CoV-2 mRNA vaccines.

The critical role of background rates of possible adverse events in the assessment of COVID-19 vaccine safety

Beginning in December of 2019, a novel coronavirus, SARS-CoV-2, emerged in China and is now a global pandemic with extensive morbidity and mortality. With the emergence of this threat, an unprecedented effort to develop vaccines against this virus began. As vaccines are now being introduced globally, we face the prospect of millions of people being vaccinated with multiple types of vaccines many of which use new vaccine platforms. Since medical events happen without vaccines, it will be important to know at what rate events occur in the background so that when adverse events are identified one has a frame of reference with which to compare the rates of these events so as to make an initial assessment as to whether there is a potential safety concern or not. Background rates vary over time, by geography, by sex, socioeconomic status and by age group. Here we describe two key steps for post-introduction safety evaluation of COVID-19 vaccines: Defining a dynamic list of Adverse Events of Special Interest (AESI) and establishing background rates for these AESI. We use multiple examples to illustrate use of rates and caveats for their use. In addition we discuss tools available from the Brighton Collaboration that facilitate case evaluation and understanding of AESI.

Vaccine hesitancy and anti-vaccination in the time of COVID-19: A Google Trends analysis

The COVID-19 pandemic has produced many calls for a vaccine. There is growing concern that vaccine hesitancy and anti-vaccination presence will dampen the uptake of a coronavirus vaccine. There are many cited reasons for vaccine hesitancy. Mercury content, autism association, and vaccine danger have been commonly found in anti-vaccination messages. It is also mused that the reduced disease burden from infectious diseases has paradoxically reduced the perceived requirement for vaccine uptake. Our analysis using Google Trends has shown that throughout the pandemic the search interest in a coronavirus vaccine has increased and remained high throughout. Peaks are found when public declarations are made, the case number increases significantly, or when vaccine breakthroughs are announced. Anti-vaccine searches, in the context of COVID-19, have had a continued and growing presence during the pandemic. Contrary to what some may believe, the burden of coronavirus has not been enough to dissuade anti-vaccine searches entirely.

Guidance for design and analysis of observational studies of fetal and newborn outcomes following COVID-19 vaccination during pregnancy

COVID-19 vaccines are now being deployed as essential tools in the public health response to the global SARS-CoV-2 pandemic. Pregnant individuals are a unique subgroup of the population with distinctive considerations regarding risk and benefit that extend beyond themselves to their fetus/newborn. As a complement to traditional pharmacovigilance and clinical studies, evidence to comprehensively assess COVID-19 vaccine safety in pregnancy will need to be generated through observational epidemiologic studies in large populations. However, there are several unique methodological challenges that face observational assessments of vaccination during pregnancy, some of which may be more pronounced for COVID-19 studies. In this contribution, we discuss the most critical study design, data collection, and analytical issues likely to arise. We offer brief guidance to optimize the quality of such studies to ensure their maximum value for informing public health decision-making.

Systematic review and meta-analysis of the effect of pertussis vaccine in pregnancy on the risk of chorioamnionitis, non-pertussis infectious diseases and other adverse pregnancy outcomes

BACKGROUND

Several countries have introduced maternal immunisation with pertussis vaccine to provide protection against pertussis in early infancy. There is increasing interest in non-specific effects of vaccines including that non-live vaccines may enhance susceptibility to non-targeted infections in females. Some studies have shown increased risk of chorioamnionitis among women receiving pertussis vaccine during pregnancy. We aimed to conduct a systematic review and meta-analysis of the effect of maternal pertussis immunisation on the risk of chorioamnionitis, as well as the secondary outcomes of non-pertussis infections in women, non-pertussis infections in infants, spontaneous abortion or stillbirth, maternal death and infant death.

METHODS

We searched PubMed and Embase for articles published until January 14, 2021. We screened articles for eligibility and extracted data using Covidence. Quality was assessed using Cochrane RoB tool and Newcastle-Ottawa Scale. Data were imported into RevMan for pooling and conduction of a meta-analysis stratified by study type. Outcomes are presented as risk ratios.

RESULTS

We identified 13 observational studies and six randomized controlled trials eligible for inclusion. We pooled data on chorioamnionitis from six observational studies and found maternal pertussis vaccine (mostly compared with other maternal immunizations with non-live vaccines) to be associated with an increased risk among the pertussis vaccinated women, RR = 1.27 [CI 95%: 1.14-1.42]. We found no difference in the analysis of our secondary outcomes of non-pertussis infections, spontaneous abortion or stillbirth and death.

CONCLUSION

We found an increased risk of chorioamnionitis among women who received pertussis vaccine in pregnancy. The large number of women receiving pertussis vaccine during pregnancy, as well as the growing evidence of non-live vaccines causing increased susceptibility to infections, indicates a need for further randomised trials to assess potential adverse effects of maternal immunisation with pertussis-containing vaccines.

Perspectives on the receipt of a COVID-19 vaccine: A survey of employees in two large hospitals in Philadelphia

Background

Health care personnel have been identified by the ACIP as a priority group for COVID-19 vaccination. We conducted a survey in November-December 2020 at two large, academic hospitals in Philadelphia to evaluate the intention of hospital employees to be vaccinated.

Methods

The survey was sent electronically to all employees (clinical and nonclinical staff) at a children’s hospital and an adult hospital. The survey was voluntary and confidential. Questions focused on plans to receive a COVID-19 vaccine when available, reasons why employees would/would not get vaccinated, when employees planned to be vaccinated, vaccine safety and efficacy features that would be acceptable, and past history of receipt of other vaccines by the employee and family. Responses were analyzed using univariate and multiple logistic regression methods.

Results

A total of 12,034 hospital employees completed the survey (a 34.5% response rate). Overall, 63.7% of employees reported that they planned to receive a COVID-19 vaccine, 26.3% were unsure, and 10.0% did not plan to be vaccinated. Over 80% of those unsure or unwilling to be vaccinated expressed concerns about vaccine side effects and the vaccines’ newness. In multivariable logistic regression, persons planning to take a COVID-19 vaccine were more likely to be older, male, more educated, Asian or White, up-to-date on vaccinations, without direct patient contact, and tested for COVID-19 in the past. No significant difference in intention to be vaccinated was found between those with higher versus lower levels of exposure to COVID-19 patients or the number of previous exposures to patients with COVID-19.

Conclusions

While the majority of hospital employees are planning to receive a COVID-19 vaccine, many are unsure or not planning to do so. Further education of hospital employees about the safety, efficacy, and value of the currently available COVID-19 vaccines is critical to vaccine acceptance in this population.

Adverse events following measles-mumps-rubella-varicella vaccine: an independent perspective on Italian pharmacovigilance data

Vaccine surveillance programs are crucial for the analysis of the vaccine’s safety profile and the guidance of health policies. The Epidemiological Observatory of the Italian Apulia Region carried out an active surveillance program of adverse effects following immunization (AEFI) after the first dose of the measles-mumps-rubella-varicella (MMRV) vaccine, finding 462 AEFIs per 1000 doses, with 11% rated serious. Applying the World Health Organization (WHO) causality assessment algorithm, 38 serious AEFIs/1000 enrolled were classified as ‘consistent causal associations’ with MMRV immunization. Severe hyperpyrexia, neurological symptoms and gastrointestinal diseases occurred in 38, 20 and 15 cases/1000 enrolled, respectively. A projection of such AEFIs in an Italian birth cohort would give tens of thousands of serious AEFIs. These incidence data are much greater than the incidence of serious AEFIs reported by the Italian Medicines Agency (AIFA) for years 2017 and 2018, mainly based on passive (or mixed) pharmacovigilance. In a previous epidemiological study in the same Italian Region, during an eight year passive surveillance, the reporting rate of serious AEFI was 0.06/1000 doses, and no cases of febrile seizures were detected applying the WHO algorithm. Taken together, the data suggest that passive pharmacovigilance is utterly inadequate to document the real incidence of serious AEFIs and that current methods of assessing causality may be questioned. Active surveillance programs are required in representative population samples, with results presented separately from those of spontaneous reporting, and causality assessment should be performed carefully and using a correct technique for AEFIs presenting as complex and multifactorial diseases, like those with serious neurologic disorders.

COVID-19 Vaccine: Critical Questions with Complicated Answers

COVID-19 has caused extensive human casualties with significant economic impacts around the globe, and has imposed new challenges on health systems worldwide. Over the past decade, SARS, Ebola, and Zika also led to significant concerns among the scientific community. Interestingly, the SARS and Zika epidemics ended before vaccine development; however, the scholarly community and the pharmaceutical companies responded very quickly at that time. Similarly, when the genetic sequence of SARSCoV-2 was revealed, global vaccine companies and scientists have stepped forward to develop a vaccine, triggering a race toward vaccine development that the whole world is relying on. Similarly, an effective and safe vaccine could play a pivotal role in eradicating COVID-19. However, few important questions regarding SARS-CoV-2 vaccine development are explored in this review.

Reports of cell-based influenza vaccine administered during pregnancy in the Vaccine Adverse Event Reporting System (VAERS), 2013-2020

BACKGROUND

In November 2012, the first cell cultured influenza vaccine, a trivalent subunit inactivated influenza vaccine (Flucelvax(®), ccIIV3), was approved in the United States for adults aged ≥18 years. A quadrivalent version (ccIIV4) was later approved in 2016 and replaced ccIIV3. The safety of ccIIV3 or ccIIV4 (ccIIV) was not assessed for pregnant women or their infants during pre-licensure studies.

OBJECTIVE

To assess the safety of ccIIV administered during pregnancy in pregnant women and their infants whose reports were submitted to VAERS during 2013-2020.

MATERIAL AND METHODS

We searched VAERS for United States reports of adverse events (AEs) in pregnant women who received ccIIV from 1 July 2013 through 31 May 2020. Clinicians reviewed reports and available medical records and assigned a primary clinical category for each report. Reports were coded as serious based on the Code of Federal Regulations definition.

RESULTS

VAERS received 391 reports following ccIIV administered to pregnant women. Twenty-four (6.1%) were serious. Two neonatal deaths were reported. No maternal deaths occurred. Among reports with trimester information (n = 340), ccIIV was administered during the second trimester in 170 (50%). The most frequent pregnancy-specific AE was premature delivery in 85 (21.7%) reports, followed by dysmature placenta in 13 (3.3%) and pre-eclampsia/eclampsia in ten (2.3%). The most common non-pregnancy specific conditions were infectious conditions in 32 (8.2%). Among infant conditions, low birth weight was reported in 62 (15.9%) reports. Fifteen birth defects were reported; in 12 with gestational age information, administration of the vaccine occurred late in the second trimester or later.

CONCLUSIONS

Review of maternal ccIIV reports in VAERS was not unexpectedly different from other maternal influenza vaccine safety VAERS reviews.

Measles-mumps-rubella vaccine at 6 months of age, immunology, and childhood morbidity in a high-income setting: study protocol for a randomized controlled trial

BACKGROUND

Measles is a highly contagious and serious infection. Before the introduction of vaccination, measles caused yearly epidemics putting vulnerable children at risk of brain damage and death. Despite safe and cost-effective vaccines, measles remains a leading cause of death in children globally. Due to insufficient vaccine coverage and low levels of in utero transferred antibodies from vaccinated mothers, outbreaks of measles in Denmark and other high-income countries are observed at increasing frequency. The current vaccine was introduced in Denmark in 1987 as a one-shot measles-mumps-rubella vaccine at 15 months, a timing chosen to avoid inhibition of the infant's immune response by maternal antibodies. One generation later, the MMR vaccinated mothers have lower antibody levels compared to the naturally infected, and their infants are already susceptible at 6 months of age or earlier, thus increasing the risk of epidemics.

METHODS

The Danish MMR trial is a double-blind randomized clinical trial recruiting between March 2019 and December 2021 with last patient last visit in February 2022. Altogether N = 6500 infants aged 6 months will be randomly assigned to intramuscular vaccination with routine MMR (M-M-R VaxPro) or placebo (solvent only). According to the Danish Childhood vaccination program, all infants will receive a routine MMR vaccination at 15 months of age. At randomization, 1 month later, and 1 month after routine MMR vaccination at 15 months of age, a blood sample is drawn from app. 10% (N = 600) of the population. Additionally, hair, saliva, and urine are sampled at randomization. The co-primary study outcomes are immunogenicity 1 month after MMR vaccination at 6 months of age assessed as plaque-reduction neutralization test, and incidence of infectious disease hospitalizations from randomization to 12 months of age. Six weeks post randomization, all participants are interviewed regarding adverse events.

TRIAL REGISTRATION

The trial is registered in the EU Clinical Trials Registry. EudraCT registration number: 2016-001901-18 . Registered on 14 February 2017.

Safety profile of rotavirus vaccines among individuals aged ≥8 months of age, United States, vaccine adverse event reporting system (VAERS), 2006-2019

INTRODUCTION

In 2006 and 2008, two live, oral rotavirus vaccines, RotaTeq (RV5) and Rotarix (RV1), were introduced into the routine immunization program in the United States. A previous rotavirus vaccine, RotaShield, was associated with an increased risk of intussusception, with data suggesting an age-dependent variation in risk. Advisory Committee on Immunization Practices (ACIP) currently recommends that RV5 or RV1 immunization be initiated by age 14 weeks and 6 days and completed by 8 months 0 days.

METHODS

We searched for U.S. VAERS reports of RV5, RV1, or unknown rotavirus vaccine brand among individuals aged ≥8 months. We analyzed reports by 2 age groups (individuals aged ≥8 months-≤5 years and ≥6 years), vaccine brand name, adverse event (AE) reported, classification of seriousness (death, non-death serious, and non-serious) and mode of exposure (direct vs. indirect exposure). For serious reports we reviewed available medical records and assigned a primary diagnosis.

RESULTS

VAERS received a total of 344 U.S. reports following rotavirus vaccination among individuals ≥8 months of age, 32 (9.3%) were serious. In the younger age-group, 307 (99%) of 309 reports followed direct vaccination of the child. In contrast, in individuals aged ≥6 years, 21 (60%) of 35 reports were via potential indirect exposure to a vaccinated child. The frequently reported AEs in the younger age-group were inappropriate schedule of drug administration 104 (34%) and drug administered to patient of inappropriate age 45 (15%); in the older group these were accidental exposure 9 (26%) and eye irritation 7 (20%). No difference in the safety profile was observed between RV1 and RV5.

CONCLUSIONS

We did not identify any unexpected AEs for RV vaccines among individuals aged ≥8 months. Health care providers should adhere to the ACIP recommended schedule and older individuals should apply necessary precautions to prevent potential secondary exposure from vaccinated children.

[High-dose trivalent influenza vaccine: safety and immunogenicity]

Las personas mayores son uno de los colectivos que más sufren los efectos de la gripe estacional. Aunque la vacuna antigripal es efectiva a la hora de prevenir la infección por el virus de la gripe y sus complicaciones, no resulta tan efectiva en personas de edad avanzada debido al fenómeno de inmunosenescencia asociado a la edad. Desde 2009 existe en EE. UU. una vacuna antigripal trivalente de alta dosis aprobada para la inmunización de personas ≥ 65 años con una concentración de antígeno cuatro veces mayor que la vacuna estándar. Múltiples ensayos clínicos llevados a cabo a lo largo de distintas temporadas, y mediante diferentes metodologías, han demostrado que la vacuna antigripal trivalente de alta dosis no solo es más efectiva, sino que además presenta un perfil de seguridad similar y es más inmunogénica que la vacuna de dosis estándar en la prevención de la gripe y sus complicaciones en personas de avanzada edad. En este documento se hace una revisión de la evidencia científica actual sobre la seguridad e inmunogenicidad de la vacuna antigripal de alta dosis en personas ≥ 65 años, y se incluye información de ensayos clínicos aleatorizados, estudios observacionales con datos de práctica clínica real y revisiones sistemáticas y metaanálisis.

Considerations for setting occupational exposure limits for novel pharmaceutical modalities

In order to develop new and effective medicines, pharmaceutical companies must be modality agnostic. As science reveals an enhanced understanding of biological processes, new therapeutic modalities are becoming important in developing breakthrough therapies to treat both rare and common diseases. As these new modalities progress, concern and uncertainty arise regarding their safe handling by the researchers developing them, employees manufacturing them and nurses administering them. This manuscript reviews the available literature for emerging modalities (including oligonucleotides, monoclonal antibodies, fusion proteins and bispecific antibodies, antibody-drug conjugates, peptides, vaccines, genetically modified organisms, and several others) and provides considerations for occupational health and safety-oriented hazard identification and risk assessments to enable timely, consistent and well-informed hazard identification, hazard communication and risk-management decisions. This manuscript also points out instances where historical exposure control banding systems may not be applicable (e.g. oncolytic viruses, biologics) and where other occupational exposure limit systems are more applicable (e.g. Biosafety Levels, Biologic Control Categories).

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Review of toxicology and pharmacology information for novel therapeutic modalities.

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Identification of occupational hazards associated with novel therapeutic modalities.

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Occupational hazards and exposure risks differ across pharmaceutical modalities.

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Occupational exposure control banding systems are not one size fits all.

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Banding system variations offer benefits while enabling proper exposure controls.

Vaccine- and natural infection-induced mechanisms that could modulate vaccine safety

A degraded/dysfunctional immune system appears to be the main determinant of serious/fatal reaction to viral infection (for COVID-19, SARS, and influenza alike). There are four major approaches being employed or considered presently to augment or strengthen the immune system, in order to reduce adverse effects of viral exposure. The three approaches that are focused mainly on augmenting the immune system are based on the concept that pandemics/outbreaks can be controlled/prevented while maintaining the immune-degrading lifestyles followed by much of the global population. The fourth approach is based on identifying and introducing measures aimed at strengthening the immune system intrinsically in order to minimize future pandemics/outbreaks. Specifically, the four measures are: 1) restricting exposure to virus; 2) providing reactive/tactical treatments to reduce viral load; 3) developing vaccines to prevent, or at least attenuate, the infection; 4) strengthening the immune system intrinsically, by a) identifying those factors that contribute to degrading the immune system, then eliminating/reducing them as comprehensively, thoroughly, and rapidly as possible, and b) replacing the eliminated factors with immune-strengthening factors. This paper focuses on vaccine safety. A future COVID-19 vaccine appears to be the treatment of choice at the national/international level. Vaccine development has been accelerated to achieve this goal in the relatively near-term, and questions have arisen whether vaccine safety has been/is being/will be compromised in pursuit of a shortened vaccine development time. There are myriad mechanisms related to vaccine-induced, and natural infection-induced, infections that could adversely impact vaccine effectiveness and safety. This paper summarizes many of those mechanisms.

The reporting sensitivity of the Vaccine Adverse Event Reporting System (VAERS) for anaphylaxis and for Guillain-Barré syndrome

BACKGROUND

Underreporting is a limitation common to passive surveillance systems, including the Vaccine Adverse Event Reporting System (VAERS) that monitors the safety of U.S.-licensed vaccines. Nonetheless, previous reports demonstrate substantial case capture for clinically severe adverse events (AEs), including 47% of intussusception cases after rotavirus vaccine, and 68% of vaccine associated paralytic polio after oral polio vaccine.

OBJECTIVES

To determine the sensitivity of VAERS in capturing AE reports of anaphylaxis and Guillain-Barré syndrome (GBS) following vaccination and whether this is consistent with previous estimates for other severe AEs.

METHODS

We estimated VAERS reporting rates following vaccination for anaphylaxis and GBS. We used data from VAERS safety reviews as the numerator, and estimated incidence rates of anaphylaxis and GBS following vaccination from the Vaccine Safety Datalink (VSD) studies as the denominator. We defined reporting sensitivity as the VAERS reporting rate divided by the VSD incidence rate. Sensitivity was reported as either a single value, or a range if data were available from >1 study.

RESULTS

VAERS sensitivity for capturing anaphylaxis after seven different vaccines ranged from 13 to 76%; sensitivity for capturing GBS after three different vaccines ranged from 12 to 64%. For anaphylaxis, VAERS captured 13-27% of cases after the pneumococcal polysaccharide vaccine, 13% of cases after influenza vaccine, 21% of cases after varicella vaccine, 24% of cases after both the live attenuated zoster and quadrivalent human papillomavirus (4vHPV) vaccines, 25% of cases after the combined measles, mumps and rubella (MMR) vaccine, and 76% of cases after the 2009 H1N1 inactivated pandemic influenza vaccine. For GBS, VAERS captured 12% of cases after the 2012-13 inactivated seasonal influenza vaccine, 15-55% of cases after the 2009 H1N1 inactivated pandemic influenza vaccine, and 64% of cases after 4vHPV vaccine.

CONCLUSIONS

For anaphylaxis and GBS, VAERS sensitivity is comparable to previous estimates for detecting important AEs following vaccination.

The use of web analytics combined with other data streams for tailoring online vaccine safety information at global level: The Vaccine Safety Net's web analytics project

The Vaccine Safety Net's Web Analytics Project (VSN-WAP) was launched in October 2017 to monitor the behavior of users visiting websites belonging to the VSN, a global network of websites providing science-based information on vaccine safety. Participating websites could provide web metrics in two ways: through a Google Analytics (GA) script, which automatically forwarded metrics to a central account and through manual input (MI) of a reduced subset of metrics (Sessions, Page Views, New Users, Bounce Rate, Views/Session and Average Session Duration), which were pooled with the metrics obtained through GA. Additional metrics were obtained from websites providing data through Google Analytics (Country, Age, Sex, Device). We report results from February 2018 to March 2019. In March 2019, 32 websites were participating in the project (21 through GA, 11 through MI). From February 2018 to March 2019 we recorded 22,471,535 sessions, with 38,307,349 page views. Sessions, New Users and Page views progressively increased, Views/Session, Bounce Rate and Average Session Duration remained stable. Most users were female (68%) and belonged to the 25-34 age range (37%), followed by 35-44 (22%) and 18-24 (19%). Fifty-four percent of users connected from a mobile device, 42% from a desktop and 4% from a tablet. Digital media monitoring techniques can provide insights on the characteristics of users with a specific interest in vaccines. These data can be exploited to improve the performance of websites providing information on vaccines to the general public.

INCLEN Intussusception Surveillance Network Study Group. Risk of intussusception after monovalent rotavirus vaccine (Rotavac) in Indian infants: A self-controlled case series analysis

Background

An association between rotavirus vaccination and intussusception has been documented in post-licensure studies in some countries. We evaluated the risk of intussusception associated with monovalent rotavirus vaccine (Rotavac) administered at 6, 10 and 14 weeks of age in India.

Methods

Active prospective surveillance for intussusception was conducted at 22 hospitals across 16 states from April 2016 through September 2017. Data on demography, clinical features and vaccination were documented. Age-adjusted relative incidence for 1–7, 8–21, and 1–21 days after rotavirus vaccination in children aged 28–364 days at intussusception onset was estimated using the self-controlled case-series (SCCS) method. Only Brighton Collaboration level 1 cases were included.

Results

Out of 670 children aged 2–23 months with intussusception, 311 (46.4%) children were aged 28–364 days with confirmed vaccination status. Out of these, 52 intussusception cases with confirmed receipt of RVV were included in the SCCS analysis. No intussusception case was observed within 21 days of dose 1. Only one case occurred during 8–21 days after the dose 2. Post-dose 3, two cases in 1–7 days and 7 cases during 8–21 days period were observed. There was no increased risk of intussusception during 1–7 days after the doses 1 and 2 (zero cases observed) or dose 3 (relative incidence [RI], 1.71 [95% confidence interval {CI} 0.0–5.11]). Similarly, no increased risk during 8–21 days after the dose 1 (zero cases observed), dose 2 (RI, 0.71 [95% CI, 0.0–3.28]) or dose 3 (RI, 2.52 [95% CI, 0.78–5.61]). The results were similar for 1–21 day periods after the doses separately or pooled.

Conclusions

The risk of intussusception during the first 21 days after any dose of rotavirus vaccine (Rotavac) was not higher among the Indian infants than the background risk, based on limited SCCS analysis of 52 children.

Post-marketing surveillance of adverse events following measles, mumps, rubella and varicella (MMRV) vaccine: retrospecive study in apulia region (ITALY), 2009-2017

Since 2006, some Italian Regions introduced the active offer of measles, mumps, rubella, and varicella (MMRV) vaccine for all newborns during the second years of life. In 2011, Italian Drug Authority (AIFA) recommended the discontinuation of the MMRV use for an increased risk of febrile seizures following vaccination; furthermore, some Regions (such as Apulia, that introduced MMRV offer in 2009) chose to continue the use of MMRV and Ministry of Health recommended to guarantee supplemental monitoring of safety of the vaccine. In Italy, the surveillance of Adverse Events following immunization (AEFIs) is currently carried out by AIFA and Regional Health Authorities; this paper aims to summarize the results of MMRV-vaccine surveillance of AEFIs program carried out in Apulia. From the AIFA database, we selected MMRV AEFIs that occurred in Apulia (about 4,000,000 inhabitants) from 2009 to 2017. For serious AEFIs, we applied the WHO causality assessment algorithm, using for cases hospitalized information from individual medical records. In the 8 years of observation, 155 MMRV-AEFIs (reporting rate: 37.9×100,000 doses) occurred of which 26 were classified as serious (6.3×100,000 doses) and 22 led to hospitalization. Performing causality assessment, for 10 the classification was "consistent causal association to immunization" (reporting rate: 2.4×100000 doses), for 2 indeterminate, for 13 "inconsistent causal association to immunization" and for 1 not-classifiable. No case of febrile seizure resulted consistent to vaccination. All consistent serious AEFIs were completely resolved at subsequent follow-up.

Adverse events following quadrivalent meningococcal diphtheria toxoid conjugate vaccine (Menactra®) reported to the Vaccine Adverse Event Reporting System (VAERS), 2005-2016

BACKGROUND

Post marketing safety evaluations of quadrivalent meningococcal diphtheria-toxoid conjugate vaccine (MenACWY-D) have focused on post-vaccination risk of Guillain Barré syndrome (GBS), adverse events (AEs) after maternal vaccination, and comparative studies with the newer quadrivalent meningococcal CRM₁₉₇ conjugate vaccine (MenACWY-CRM). To provide an updated general safety assessment, we reviewed reports of AEs following MenACWY-D submitted to the Vaccine Adverse Event Reporting System (VAERS).

METHODS

VAERS is a national spontaneous reporting vaccine safety surveillance system co-administered by the Centers for Disease Control and Prevention and the U.S. Food and Drug Administration. We searched the VAERS database for U.S. reports of AEs after administration of MenACWY-D from January 2005 through June 2016. We conducted clinical reviews of serious reports after MenACWY-D administered alone, reports of MenACWY-D use during pregnancy, and reports of selected pre-specified outcomes. We screened for disproportionate reporting of AEs after MenACWY-D using empirical Bayesian data mining.

RESULTS

VAERS received 13,075 U.S. reports after receipt of MenACWY-D; most (86%) described vaccination in adolescents, were classified as non-serious (94%), and described AEs consistent with pre-licensure studies. We did not find any evidence that reported deaths were related to vaccination. In serious reports, GBS and meningococcal infection were the most commonly reported medical conditions. Many reports of MenACWY-D use during pregnancy described inadvertent vaccination; most (61%) did not report any AE.

CONCLUSIONS

Findings from our comprehensive review of reports to VAERS following MenACWY-D are consistent with data from pre-licensure studies and provide further reassurance on the safety of MenACWY-D.

Safety evaluation of adverse events following vaccination with Havrix, Engerix-B or Twinrix during pregnancy

BACKGROUND

Vaccination of pregnant women against hepatitis A virus (HAV) or hepatitis B virus (HBV) may benefit the mother and the fetus but is not routinely recommended. However, the risk associated with vaccination should be weighed against the risk of HAV or HBV infection. Data on safety profiles after hepatitis A, B or combined AB immunization during pregnancy are limited.

METHODS

We searched the GSK Worldwide Safety Database for adverse events (AEs) following immunization of pregnant women with HAV (Havrix, GSK), HBV (Engerix-B, GSK) or the combined hepatitis AB (Twinrix, GSK) vaccine since market authorization through 31 January 2018, covering at least 25 years. AE reports (spontaneous, post-marketing surveillance and clinical trial cases) in the GSK Worldwide Safety Database were identified using a systematic search and were reviewed by clinicians to ascertain pregnancy status at time of vaccination and characterize adverse pregnancy outcomes, including pregnancy-related AEs and AEs in infants regardless of the causality assessment.

RESULTS

Overall, 613, 700 and 363 pregnancies with exposure to Havrix, Engerix-B and Twinrix, respectively, were reported. Of these, 378, 339 and 194 were analyzed. The most frequently identified pregnancy outcomes were live infants (288, 223 and 151), spontaneous abortions (43, 57 and 26) and elective terminations (25, 24 and 9). A total of 19, 29 and 10 cases of congenital anomalies were reported. Of these, 17, 20 and 7 were major birth defects. The most commonly reported pregnancy-related AE and AE in infants were premature delivery (28) and jaundice (11), respectively. No maternal deaths were reported. Congenital anomalies were reported in all recorded infant deaths.

CONCLUSIONS

This review did not indicate any concerning pattern of adverse pregnancy outcomes following exposure to any of the 3 vaccines during pregnancy.

Adverse events following HPV vaccination: 11 years of surveillance in Australia

BACKGROUND

Australia was the first country to implement a fully funded vaccination program with quadrivalent human papillomavirus vaccine (4vHPV) in 2007, including males from 2013. We examined adverse events (AE) following vaccination with 4vHPV from 11 years of post-marketing data, focusing on a period of enhanced surveillance and adverse events of special interest (AESI).

METHODS

AE following 4vHPV doses administered between April 2007 and December 2017 reported to Australia's national regulator, the Therapeutic Goods Administration, were examined; reports collected during enhanced surveillance in 2013 and 2014 were analyzed separately. Age and sex-specific rates, using denominator data from the national HPV vaccination register, were determined. Pre-specified AESI were identified using Medical Dictionary for Regulatory Activities (MedDRA®) Preferred Terms and examined in detail.

FINDINGS

Following nine million doses of 4vHPV vaccine administered in Australia, 4551 AE reports were identified. The crude reporting rate was 39.8 per 100 000 doses in the funded cohorts, excluding the enhanced surveillance period. The reported rate of syncope in 12 to 13-year-old males and females was 29.6 per 100 000 doses during enhanced surveillance and 7.1 per 100 000 doses during the remaining study period; rates of syncope were higher in younger compared to older adolescents. The rate of anaphylaxis (0.32 per 100 000 doses) was consistent with published rates. Other AESI including autoimmune disease, postural orthostatic tachycardia syndrome, primary ovarian insufficiency, Guillain-Barré syndrome, complex regional pain syndrome and venous thromboembolism, were reported at low rates and analysis did not reveal unexpected patterns that would suggest causal association.

INTERPRETATION

AESI, apart from syncope, were reported rarely. The higher rate of syncope among younger adolescents highlights the need for management protocols to prevent syncope-related injury. Analysis of this large, longitudinal dataset in a country with high vaccine uptake, including a period of enhanced surveillance, affirms the safety profile of 4vHPV.

Maternal and infant outcomes following exposure to quadrivalent human papillomavirus vaccine during pregnancy

INTRODUCTION

The Department of Defense encourages service members ≤26 years of age to receive the human papillomavirus (HPV) vaccine. Although this vaccine is not recommended in pregnancy, inadvertent vaccination may occur. The objective of this study was to assess whether active duty US military women who received the quadrivalent HPV vaccine (4vHPV) during pregnancy were at increased risk for adverse maternal or infant outcomes.

METHODS

The study population included active duty US military women aged 17-28 years with at least one pregnancy between 2007 and 2014, and the infants resulting from those pregnancies. Pregnancies, live births, and outcomes were identified using medical codes in administrative medical records. Exposure to 4vHPV during pregnancy was ascertained from personnel immunization records. Multivariable regression models were used to calculate risk estimates and 95% confidence intervals for the maternal outcomes of spontaneous abortion, preeclampsia/eclampsia and preterm labor, and the infant outcomes of preterm birth, birth defects, growth problems in infancy or in utero, and infant sex.

RESULTS

Overall, 90,600 pregnancies and 75,670 singleton infants were identified. Approximately 2% of pregnancies and infants were exposed to 4vHPV during pregnancy. After adjustments, no positive associations were detected between inadvertent exposure to 4vHPV during pregnancy and any adverse pregnancy or infant outcomes.

DISCUSSION

Our findings add to an established body of literature demonstrating the safety of 4vHPV when inadvertently administered during pregnancy. Although 4vHPV is no longer administered in the US, its use continues overseas; therefore, safety studies remain important. Furthermore, such studies can provide reassurance to women inadvertently exposed to nonavalent HPV vaccine (9vHPV) in pregnancy, which protects against four of the same antigens as 4vHPV, since safety of 9vHPV has not yet been established in pregnant women.

Monitoring the safety of high-dose, trivalent inactivated influenza vaccine in the vaccine adverse event reporting system (VAERS), 2011 - 2019

BACKGROUND

On 12/23/2009 a new high-dose trivalent inactivated influenza vaccine (IIV3-HD) was licensed for adults aged ≥65 years. We assessed the post-licensure safety data for IIV3-HD in the Vaccine Adverse Event Reporting System (VAERS) during 2011-2019.

METHODS

We searched VAERS for reports after IIV3-HD during 1/1/2011-06/30/2019 in persons aged ≥65 years. Medical records were reviewed for all death reports and for certain pre-specified conditions (e.g. Guillain Barré Syndrome [GBS], anaphylaxis). We also reviewed certain groups who received IIV3-HD erroneously (e.g. pregnant women, children). Empirical Bayesian data mining was used to identify disproportional reporting.

RESULTS

VAERS received 12,320 reports after IIV3-HD;723 reports (5.9%) were serious. The most common adverse events (AEs) among serious reports were pyrexia (30.2%), asthenia (28.9%), and dyspnea (24.9%), and among non-serious reports were injection site erythema (16.8%), pain in extremity (15.8%), and injection site pain (14.2%). Among 55 death reports, the most common causes of death were diseases of the circulatory system (n = 23;41.8%). Based on medical record review, there were 61 reports of GBS and 13 of anaphylaxis. There were 13 reports of pregnant-women who inadvertently received IIV3-HD; three reports described arm pain or local reactions, and 10 did not report any AE. Among 59 reports of children who erroneously received IIV3-HD, 31 experienced an AE (most commonly injection site or constitutional reactions) and the remaining 28 reports did not describe any AE.

CONCLUSIONS

Post-licensure safety data of IIV3-HD during 9 influenza seasons revealed no new or unexpected safety concerns among individuals ≥65 years. Inadvertent administration of IIV3-HD to children or pregnant women was observed, although with no serious AEs reported. Training and education of providers in vaccine recommendations and groups for whom the vaccine is indicated may help in preventing these vaccine administration errors. This review provides baseline information for future monitoring of the quadrivalent-high-dose influenza vaccine.

Adverse events following immunization with the live-attenuated recombinant Japanese encephalitis vaccine (IMOJEV®) in Taiwan, 2017-18

BACKGROUND

Japanese encephalitis (JE) is a significant public health concern in the Asia-Pacific region, with a case-fatality rate of around 20% for those who develop encephalitis. Mouse-brain derived vaccines against JE have been used in the publicly funded national immunization program (NIP) in Taiwan since 1968. They were replaced with a live-attenuated recombinant vaccine (JE-CV, IMOJEV®) in May 2017. We assessed reports of adverse events (AE) following the introduction of JE-CV into the Taiwan NIP to characterize its post-licensure safety profile.

METHODS

AEs reported between 1 May 2017 and 31 December 2018 post vaccination with JE-CV were extracted from the National Adverse Drug Reactions (ADR) Reporting System, a passive surveillance system run by the Taiwan Food and Drug Administration. The report rates were calculated based on the number of doses distributed by the manufacturer during the assessment period.

RESULTS

There were 51 AEs reported among 30 subjects (12 girls and 18 boys; mean age 25 months), with a reporting rate of 4.7 AEs per 100,000 doses distributed. The AEs occurred after a median of. 1-day post vaccination. Eight subjects had received concomitant vaccination with another vaccines. There were four serious AEs reported: febrile seizure, acute renal failure, viral respiratory tract infection, and injection site cellulitis. None of these serious AEs were classified as being causally related to JE-CV vaccination.

CONCLUSION

These post-licensure AE surveillance data confirm the favorable safety profile of JE-CV.

Assessment of risk of intussusception after pilot rollout of rotavirus vaccine in the Indian public health system

BACKGROUND

Pre-licensure trials of ROTAVAC® were not adequately powered to assess risk of intussusception, a rare adverse event associated with other rotavirus vaccines in some settings. We examined the risk of intussusception after ROTAVAC® vaccination among Indian infants during pilot rollout of the vaccine in the public health system in three states - Himachal Pradesh, Maharashtra and Tamil Nadu.

METHODS

Passive surveillance for intussusception was set up in 35 sentinel health facilities covering 26.3 million population in the three states under monitoring of an Interministerial-Interagency Steering Committee. Clinical and immunization data were collected by independent teams. An expert committee blinded to vaccination status, classified intussusception cases using Brighton criteria. The self-controlled case-series method was used to estimate risk of intussusception (Brighton Level 1) after ROTAVAC® vaccination.

RESULTS

151 intussusception cases were included in the analysis. The relative incidence (incidence during the risk period compared to the control period) 1-21 days after doses 1 and 2 combined was 1.56 (95% CI, 0.0-5.28) and that for three doses combined was 1.88 (95% CI, 0.76-4.30). Attributable risk 1-21 days after doses 1 and 2 combined was 0.11 (95% CI, 0.0-0.25) and that for 3 doses combined was 0.42 (95% CI, 0.0-0.70) per 100,000 doses.

CONCLUSIONS

No increased risk of intussusception within 21 days of receipt of the first two doses combined or all 3 doses combined of ROTAVAC® was detected.

Lessons on causality assessment and communications from the 2019 South-East Asia Regional (SEAR) workshop on inter-country expert review of selected Adverse Events Following Immunization (AEFI) cases

BACKGROUND

Surveillance of AEFI is fundamental for improving safety and maintaining public support for vaccination. In SEAR, billions of doses of vaccine are given annually. The objective of the 2019 SEAR AEFI training workshop was to further strengthen in-country vaccine safety, assess capacity compared to 2014 and to better integrate communication into the AEFI causality assessment program.

METHODS

A 3 ½ day workshop with AEFI experts from all 11 SEAR countries. Participants outlined each county's AEFI data, critiqued their AEFI program, reviewed and critiqued causality assessment of 23 anonymized serious AEFI cases and proposed communication plans for each.

RESULTS

Between 2016 and 2018, over 2.9 billion doses of vaccine were given in SEAR. Compared to 2014, AEFI detection and causality assessment skills had improved. AEFI experts' communication planning skills markedly improved during the workshop. Good concordance was found between country causality assessment findings and the workshop critiques. A list of targeted recommendations (country, regional and global levels) arose from the workshop.

CONCLUSIONS

SEAR countries have much improved their AEFI detection and causality assessment expertise since 2014. Given the high volume of doses administered and the AEFI technical expertise, SEAR countries can well monitor safety of regionally produced vaccines. Integration of AEFI communication into AEFI causality assessment can help mitigate potential negative impacts of serious AEFIs.

Active SMS-based surveillance of adverse events following immunisation with influenza and pertussis-containing vaccines in Australian pregnant women using AusVaxSafety

BACKGROUND

Maternal immunisation is important to protect both mother and baby, but safety concerns can lead to low uptake. AusVaxSafety participant-based surveillance actively monitors adverse events following immunisation (AEFI) in Australia. We aimed to analyse AEFI in the days following vaccination with seasonal inactivated influenza vaccine (IIV) and/or reduced antigen diphtheria-tetanus-acellular pertussis vaccine (dTpa) in pregnant women in Australia.

METHODS

De-identified AEFI reports were solicited from vaccine recipients via automated SMS survey (using SmartVax software) following routine vaccination with IIV and/or dTpa at 219 national sentinel surveillance sites from 2015 to 2018. AEFI rates were compared by vaccine group (IIV alone, dTpa alone, or IIV and dTpa together), vaccine brand, trimester (IIV only) and vaccination period (April to August 2016-2018; IIV only). Women who had two vaccination encounters during surveillance were identified and AEFI rates compared for each dose.

RESULTS

Among 13,758 participants, overall AEFI rates were lower following IIV (4.9%) than dTpa (6.4%) or IIV and dTpa given concomitantly (7.4%). The AEFI profile was similar for both vaccines, with injection site reactions, tiredness, and headache most commonly reported. Injection site pain and swelling/redness were significantly more common in women who received dTpa than IIV. Reports of medical attendance following immunisation were similar (0.3%) for each vaccine group. AEFI rates did not differ by IIV brand (FluQuadri®, Fluarix® Tetra), dTpa brand (Boostrix®, Adacel®), or by trimester. Among women with sequential dTpa vaccinations, 6.0% (7/116) had an AEFI following their second dTpa dose.

CONCLUSIONS

Self-reported AEFI rates did not differ by trimester (IIV), or by vaccine brand (IIV or dTpa). Concomitant influenza and pertussis vaccination was associated with more frequent, but low rates of minor, expected AEFI. These real world 'citizen science-based' data provide further reassuring evidence of the safety of maternal vaccination.

Nephrotic syndrome in infants and toddlers before and after introduction of the meningococcal B vaccine programme in England: An ecological study

A possible increased risk of nephrotic syndrome (NS) following a meningococal group B vaccination campaign was identified during active safety surveillance in a province in Quebec, Canada where 4 cases were reported from an exposed population of ~490,000, a higher rate than in provinces not using the vaccine. Meningococcal B vaccine has been given routinely at 2, 4 and 12 months of age in the United Kingdom since September 2015. To investigate the Canadian signal we used English hospital admissions data from 2005 to 2019 in 2-23 month old children to determine whether the rate of NS changed following the introduction of the vaccine. The analysis was stratified by age 2-5 months, 6-11 months, 12-17 months and 18-23 months. The results showed no evidence of an increased risk with incidence rate ratios between 0.81 (95% confidence interval 0.56-1.19) for age 6-11 months and 1.18 (0.84-1.66) for age 12-17 months.

Consensus summary report for CEPI/BC March 12-13, 2020 meeting: Assessment of risk of disease enhancement with COVID-19 vaccines

A novel coronavirus (CoV), Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in late 2019 in Wuhan, China and has since spread as a global pandemic. Safe and effective vaccines are thus urgently needed to reduce the significant morbidity and mortality of Coronavirus Disease 2019 (COVID-19) disease and ease the major economic impact. There has been an unprecedented rapid response by vaccine developers with now over one hundred vaccine candidates in development and at least six having reached clinical trials. However, a major challenge during rapid development is to avoid safety issues both by thoughtful vaccine design and by thorough evaluation in a timely manner. A syndrome of “disease enhancement” has been reported in the past for a few viral vaccines where those immunized suffered increased severity or death when they later encountered the virus or were found to have an increased frequency of infection. Animal models allowed scientists to determine the underlying mechanism for the former in the case of Respiratory syncytial virus (RSV) vaccine and have been utilized to design and screen new RSV vaccine candidates. Because some Middle East respiratory syndrome (MERS) and SARS-CoV-1 vaccines have shown evidence of disease enhancement in some animal models, this is a particular concern for SARS-CoV-2 vaccines. To address this challenge, the Coalition for Epidemic Preparedness Innovations (CEPI) and the Brighton Collaboration (BC) Safety Platform for Emergency vACcines (SPEAC) convened a scientific working meeting on March 12 and 13, 2020 of experts in the field of vaccine immunology and coronaviruses to consider what vaccine designs could reduce safety concerns and how animal models and immunological assessments in early clinical trials can help to assess the risk. This report summarizes the evidence presented and provides considerations for safety assessment of COVID-19 vaccine candidates in accelerated vaccine development.

Review of pediatric encephalitis and encephalopathy cases following immunization reported to the Canadian Immunization Monitoring Program Active (IMPACT) from 1992 to 2012

BACKGROUND

Neurological adverse events following immunization (AEFI) remain poorly characterized. Our objective was to describe pediatric acute and chronic encephalopathy and encephalitis cases following immunization reported via active sentinel surveillance from 1992 to 2012.

METHODS

This case series provides a descriptive analysis of encephalopathy/encephalitis admissions reported to the Canadian Immunization Monitoring Program ACTive (IMPACT). Acute cases were reported if symptom onset (seizures, decreased level of consciousness, change in mental status) occurred 0-7 days after tetanus or pertussis-containing vaccines, 0-15 days after other inactivated vaccines, or 5-30 days after live vaccines. Chronic cases of subacute sclerosing panencephalitis or subacute progressive rubella encephalitis were reported at any interval after vaccination. Clinical data were examined to identify possible causes for encephalopathy/encephalitis other than vaccination.

RESULTS

Sixty-one cases of encephalopathy/encephalitis following immunization were reported to IMPACT over 21 years; 57 (93.4%) were classified as acute and 4 (6.6%) were chronic cases of subacute sclerosing panencephalitis. Most patients (73.8%) were previously healthy and immunocompetent. The vaccines most frequently administered prior to presentation were diphtheria-tetanus-pertussis, measles-mumps-rubella, and influenza. At discharge, 38 patients (62.3%) had normal neurological status or were expected to recover. Forty patients (70.2%) with acute encephalopathy/encephalitis had a more likely alternate etiology besides vaccination based on neuroimaging, symptoms suggestive of infection, laboratory-confirmed non-vaccine-related infection, or clinical diagnosis. No cases of encephalitis were causally associated with pertussis or influenza vaccines. Two patients (50%) with subacute sclerosing panencephalitis had known wild-type measles infection prior to immunization. Three deaths were reported during hospitalization (4.9%); all were acute encephalitis/encephalopathy cases and none were confirmed to be vaccine-related.

CONCLUSIONS

Encephalopathy/encephalitis following immunization remains a rare but serious adverse event. Most cases had another more likely etiology than vaccination. Continued monitoring and analysis of AEFI is paramount to ensure the safety of immunization programs.

Obstetrics risk Assessment: Evaluation of selection criteria for vaccine research studies in pregnant women

Vaccines designed for use in pregnancy and vaccine trials specifically involving pregnant women are rapidly expanding. One of the key challenges in designing maternal immunization trials is that developing exclusion criteria requires understanding and quantifying the background risk for adverse pregnancy outcomes in the pregnancy being studied, which can occur independent of any intervention and be unrelated to vaccine administration. The Global Alignment of Immunization Safety Assessment in Pregnancy (GAIA) project has developed and published case definitions and guidelines for data collection, analysis, and evaluation of maternal immunization safety in trials involving pregnant women. Complementing this work, we sought to understand how to best assess obstetric risk of adverse outcomes and differentiate it from the assessment of vaccine safety. Quantification of obstetric risk is based on prior and current obstetric, and maternal medical history. We developed a step-wise approach to evaluate and quantify obstetric and maternal risk factors in pregnancy based on review of published literature and guidelines, and critically assessed these factors in the context of designing inclusion and exclusion criteria for maternal vaccine studies. We anticipate this risk assessment evaluation may assist clinical trialists with study design decisions, including selection of exclusion criteria for vaccine trials involving pregnant women, consideration of sub-group classification, such as high or low risk subjects, or schedule considerations, such as preferred trimester of gestation for an intervention during pregnancy. Additionally, this tool may be utilized in data stratification at time of study analyses.

Zebrafish as an alternative animal model in human and animal vaccination research

Much of medical research relies on animal models to deepen knowledge of the causes of animal and human diseases, as well as to enable the development of innovative therapies. Despite rodents being the most widely used research model worldwide, in recent decades, the use of the zebrafish (Danio rerio) model has exponentially been adopted among the scientific community. This is because such a small tropical freshwater teleost fish has crucial genetic, anatomical and physiological homology with mammals. Therefore, zebrafish constitutes an excellent experimental model for behavioral, genetic and toxicological studies which unravels the mechanism of various human diseases. Furthermore, it serves well to test new therapeutic agents, such as the safety of new vaccines. The aim of this review was to provide a systematic literature review on the most recent studies carried out on the topic. It presents numerous advantages of this type of animal model in tests of efficacy and safety of both animal and human vaccines, thus highlighting gains in time and cost reduction of research and analyzes.

Vaccine Safety

The details of vaccine development, licensing, and monitoring have never been more important and relevant to the health care conversation in the United States. The potential exists for a preventive medicine such as a vaccine to cause harm, and physicians and patients need to understand the real balance of risks and benefits of immunization. Vaccines given in the United States undergo rigorous testing before licensure as well as extensive postlicensure safety monitoring.

Safety of live attenuated herpes zoster vaccine in adults 70-79 years: A self-controlled case series analysis using primary care data from Australia's MedicineInsight program

BACKGROUND

Australia introduced a funded shingles vaccination program for older adults in November 2016, administered predominantly in primary care clinics. MedicineInsight, a nationally representative primary care database, was used to investigate the risk of pre-specified outcomes following live attenuated herpes zoster vaccine (ZVL) in Australia.

METHODS

Individuals aged 70-79 years who received ZVL between 1 November 2016 and 31 July 2018 were identified from MedicineInsight. The self-controlled case series (SCCS) method was used to estimate the seasonally-adjusted relative incidence (RI) of seven pre-specified outcome events (injection site reaction (ISR) [positive control], burn [negative control], myocardial infarction (MI), stroke, rash, rash with an antiviral prescription, and clinical attendance) during a plausible post-vaccination at-risk window compared with times distant from vaccination. Sensitivity analyses examined the effect of common concomitant vaccinations and restriction to first outcome events.

RESULTS

A total of 332,988 vaccination encounters among 150,054 individuals were identified during the study period; over 2 million clinical attendances were observed. There was an increased RI of ISR in the seven days following ZVL (RI = 77.4, 95% CI 48.1-124.6); the RI of clinical attendance (RI = 0.94, 95% CI 0.94-0.95) and stroke (RI = 0.58, 95% CI 0.44-0.78) were lower in the 42 days following administration of ZVL compared to control periods. There was no evidence of a change in the RI of MI (RI = 0.74, 95% CI 0.41-1.33), rash (RI = 0.97, 95% CI 0.88-1.08), or rash with antiviral prescription (RI = 0.83, 95% CI 0.62-1.10) in the 42 days following ZVL compared to control periods.

CONCLUSION

No new safety concerns were identified for ZVL in this study based on a novel, Australian primary care data source. An expected increased risk of ISR was identified; findings in relation to cardiovascular disease were reassuring but require confirmation using additional data, including hospital records.

Age inappropriate influenza vaccination in infants less than 6 months old, 2010-2018

BACKGROUND

Annual influenza vaccination is recommended for persons 6 months or older and vaccination in infants less than 6 months old is a vaccine administration error. There are limited safety studies in this population, particularly among infants less than 6 weeks old.

METHODS

We searched the U.S. Vaccine Adverse Event Reporting System (VAERS) database for reports of adverse events (AEs) following influenza vaccination in infants less than 6 months old for the 2010-2018 influenza seasons. We conducted a descriptive and qualitative analysis of reports to describe AEs and identify possible risk factors.

RESULTS

In total, 114 reports were identified; only 21 reported a specific AE. Pyrexia, irritability, crying and diarrhea were the most common symptoms. There were 12 reports involving newborns; the most common circumstance cited was confusion with the birth dose of hepatitis B vaccine. The following risk factors were identified: (1) individuals getting vaccinated together resulting in patient mix-ups; (2) healthcare provider not verifying the patient's information; (3) individual provider confusion due to similarities in vaccines' packaging and names of vaccines that sound alike.

CONCLUSIONS

Reports identified of influenza vaccination in infants less than 6 months old indicate that vaccination errors in this age group are occurring and healthcare providers who vaccinate infants should be aware of how to prevent such events. Our study adds to the existing literature by providing valuable information regarding the general absence of serious adverse events in the case of vaccination errors associated with inadvertent influenza vaccine within this population.

Investigating the association of receipt of seasonal influenza vaccine with occurrence of anesthesia/paresthesia and severe headaches, Canada 2012/13-2016/17, the Canadian Vaccine Safety Network

BACKGROUND

Concern about adverse events following immunization is frequently cited by both those who receive or decline vaccines. Neurological adverse events are especially concerning.

OBJECTIVES

Our aim was to detect associations between seasonal influenza vaccination and the occurrence of severe anesthesia/paresthesia or severe headaches.

METHODS

Data were analyzed from the Canadian National Vaccine Safety network. Events occuring on days 0-7 were self-reported and prevented daily activity, led to school or work absenteeism, or required medical attention. Controls were the previous year's vaccinees; events in controls were collected prior to the start of the influenza vaccination program of each year (2012/13 through 2016/17). Multivariable logistic regression was used to determine the association between seasonal influenza vaccination and the occurrence of anesthesia/paresthesia or severe headaches.

RESULTS

The total sample was 107,565 for investigating anesthesia/paresthesia and 97,420 for investigating severe headaches. Anesthesia/paresthesia was reported by 104/107,565 (0.10%) participants; 63/69,129 (0.09%) vaccinees and 41/38,436 (0.11%) controls (adjusted odds ratio (aOR) = 0.89; 95% CI = 0.60, 1.32). Severe headaches were reported by 1361/97,420 (1.40%) participants; 907/61,463 (1.48%) vaccinees and 454/35,957 (1.26%) controls (aOR = 1.21; 95% CI = 1.08, 1.36). No specific vaccine product was associated with severe headaches.

CONCLUSIONS

Our study found no association between severe anesthesia/paresthesia and seasonal influenza vaccination. While there was an association with severe headaches as an adverse event following influenza vaccination, the rates of these events are similar to rates reported from clinical trials and are not a cause for additional concern.

Chinese social media suggest decreased vaccine acceptance in China: An observational study on Weibo following the 2018 Changchun Changsheng vaccine incident

China is home to the world's largest population, with the potential for disease outbreaks to affect billions. However, knowledge of Chinese vaccine acceptance trends is limited. In this work we use Chinese social media to track responses to the recent Changchun Changsheng Biotechnology vaccine scandal, which led to extensive discussion regarding vaccine safety and regulation in China. We analyzed messages from the popular Chinese microblogging platform Sina Weibo in July 2018 (n = 11,085), and August 2019 (n = 500). Thus, we consider Chinese vaccine acceptance, before, during, immediately after, and one year after the scandal occurred. Results show that expressions of distrust in government pertaining to vaccines increased significantly during and immediately after the scandal. Self-reports of vaccination occurred both before, and one year after, the scandal; however, these self-reports changed from positive endorsements of vaccination to concerns about vaccine harms. Data suggest that expressed support for vaccine acceptance in China may be decreasing.

Prevalence and types of vaccination errors from 2009 to 2018: A systematic review of the medical literature

INTRODUCTION

Vaccination practices and the programmatic factors that influence them are essential for public health. Several barriers impact vaccination efforts, including vaccination errors, which pose the risk of reduced population-wide vaccination efficacy and individual adverse drug events. This study aimed to define the prevalence of vaccination errors documented in English language medical literature between 2009 and 2018 and to identify the common types of errors that occurred during this period.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) guidelines. The study protocol was registered with the International Prospective Register of Systematic Reviews prior to research activities. The Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, Google Scholar, ProQuest Central, PubMed, Scopus, and Web of Science were searched using predetermined search terms. Included data were from primary studies or retrospective analyses that assessed the prevalence and/or type of vaccination errors and that were peer-reviewed, conducted between 2009 and 2018, and published in English. Data were extracted using the Cochrane Data Extraction and Assessment Template and assessed using the Appraisal tool for Cross-Sectional Studies. Pooled vaccination error prevalence was then calculated.

RESULTS

Of the 1310 independent records that were identified and screened, 17 studies from five countries met all inclusion criteria. Pooled vaccination error prevalence was calculated to be 1.15 per 10,000 vaccine doses (range, 0.005-141.69 per 10,000 doses). The most commonly reported vaccination errors were "wrong vaccine administered" and "off-schedule administration."

CONCLUSIONS

International rates of vaccination error reporting remain low, with few reports of significant adverse reactions. Vaccination programs should consider the impact of vaccination errors on individual and population health, particularly focusing on the impact of "wrong vaccine" administration. Continued monitoring and promotion of error reporting will enable further understanding of this topic.

Safety of influenza vaccination on adverse birth outcomes among pregnant women: A prospective cohort study in Japan

BACKGROUND

Pregnant women are in the highest priority group for receiving influenza vaccination. However, they may be reluctant to receive the vaccination due to concerns about the influence of vaccination on the fetuses.

METHODS

This prospective cohort study of 10 330 pregnant women examined the safety of influenza vaccination in terms of adverse birth outcomes. Influenza vaccination during pregnancy was determined from questionnaires before and after the 2013/2014 influenza season. All subjects were followed until the end of their pregnancy. Adverse birth outcomes, including miscarriage, stillbirth, preterm birth, low birth weight, and malformation, were assessed by obstetrician reports.

RESULTS

Adverse birth outcomes were reported for 641 (10%) of the 6387 unvaccinated pregnant women and 356 (9%) of the 3943 vaccinated pregnant women. Even after adjusting for potential confounders, vaccination during pregnancy showed no association with the risk of adverse birth outcomes (odds ratio 0.90, 95% confidence interval 0.76-1.07). Vaccination during the first or second trimester displayed no association with adverse birth outcomes, whereas vaccination during the third trimester was associated with a decreased risk of adverse birth outcomes (odds ratio 0.70, 95% confidence interval 0.51-0.98).

CONCLUSIONS

Influenza vaccination during pregnancy did not increase the risk of adverse birth outcomes, regardless of the trimester in which vaccination was performed, when compared to unvaccinated pregnant women.

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

BACKGROUND

The tetanus, diphtheria, and acellular pertussis (Tdap) vaccine was approved for U.S. adults in 2005 and recommended for administration in every pregnancy in 2012, with optimal timing between 27 and 36 weeks' gestation. In the military, however, a current Tdap vaccination status is compulsory for service, and active duty women may be inadvertently exposed in early pregnancy. Safety data in this population are limited.

OBJECTIVES

To assess safety of inadvertent (0-13 weeks' gestation) and recommended (27-36 weeks' gestation) exposure to the Tdap vaccine in pregnancy.

METHODS

Pregnancies and live births from Department of Defense Birth and Infant Health Research program data were linked with military personnel immunization records to determine pregnancy Tdap vaccine exposure among active duty women, 2006-2014. Multivariable Cox and generalized linear regression models estimated associations between Tdap vaccine exposure and adverse pregnancy or infant outcomes.

RESULTS

Of 145,883 pregnancies, 1272 were exposed to the Tdap vaccine in the first trimester and 9438 between 27 and 36 weeks' gestation. Neither inadvertent nor recommended vaccine exposure were associated with spontaneous abortion, preeclampsia, or preterm labor. Among 117,724 live born infants, 984 were exposed to the Tdap vaccine in the first trimester and 9352 between 27 and 36 weeks' gestation. First trimester exposure was not associated with birth defects, growth problems in utero, growth problems in infancy, preterm birth, or low birth weight. Tdap vaccine exposure between 27 and 36 weeks' gestation was not associated with any adverse infant outcome.

CONCLUSIONS

Among a population of active duty women in the U.S. military who received the Tdap vaccine during pregnancy, we detected no increased risks for adverse maternal, fetal, or infant outcomes. Our findings corroborate existing literature on the safety of exposure to the Tdap vaccine in pregnancy.

Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017-2018

BACKGROUND

Annual vaccination against seasonal influenza is widely recognized as the primary intervention method in preventing morbidity and mortality from influenza, but coverage among adults is suboptimal in the United States. Safety and effectiveness perceptions regarding vaccines are consistently cited as factors that influence adults' decisions to accept or reject vaccination. Therefore, we conducted this analysis in order to understand sociodemographic, attitude, and knowledge factors associated with these perceptions for influenza vaccine among adults in three different age groups.

METHODS

Probability-based Internet panel surveys using nationally representative samples of adults aged ≥19 years in the United States were conducted during February-March of 2017 and 2018. We asked respondents if they believed the influenza vaccine was safe and effective. We calculated prevalence ratios using chi-square and pairwise t-tests to determine associations between safety and effectiveness beliefs and sociodemographic variables for adults aged 19-49, 50-64, and ≥65 years.

RESULTS

Survey completion rates were 58.2% (2017) and 57.2% (2018); we analyzed 4597 combined responses. Overall, most adults reported the influenza vaccine was safe (86.3%) and effective (73.0%). However, fewer younger adults reported positive perceptions compared with older age groups. Respondents who believed the vaccine was safe also reported it was effective.

CONCLUSIONS

Generally, adults perceived the influenza vaccine as safe and effective. Considering this, any improvements to these perceptions would likely be minor and have a limited effect on coverage. Future research to understand why, despite positive perceptions, adults are still choosing to forego the vaccine may be informative.

Safety review of tetanus toxoid, reduced diphtheria toxoid, acellular pertussis vaccines (Tdap) in adults aged ≥65 years, Vaccine Adverse Event reporting System (VAERS), United States, September 2010-December 2018

INTRODUCTION

The Advisory Committee on Immunization Practices (ACIP) recommends vaccination with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) in persons ≥65 years of age. To date, few studies have assessed the safety of Tdap in this population. We aimed to summarize reports submitted to the Vaccine Adverse Event Reporting System (VAERS) following receipt of Tdap in this age group.

METHODS

We searched for and analyzed U.S. VAERS reports of Tdap among individuals ≥65 years of age submitted from September 1, 2010 through December 31, 2018. We classified reports according to concurrent vaccination, seriousness, and outcome (death, non-death) and determined the frequency of reported adverse events (AEs). For serious reports, we reviewed available medical records. Data mining analyses were undertaken to detect disproportionality in reporting.

RESULTS

VAERS received a total of 1,798 reports following Tdap, of which 104 (6%) were serious. The most common AEs were injection site erythema (26%; n = 468), injection site pain (19%; n = 335), injection site swelling (18%; n = 329), and erythema (18%; n = 321). We identified seven deaths; none were attributed to Tdap. Among serious non-death reports, nervous system disorders (35.1%; n = 34) and infections and infestations (n = 18.6%; n = 18) were most commonly reported. Data mining did not identify any vaccine-AE combination reported more frequently than expected.

CONCLUSIONS

We did not identify any new safety concern over nearly a decade of recommended Tdap use among adults ≥65 years of age. Findings from this post-marketing review are consistent with prior post-marketing observations and pre-licensure studies.

Erythema multiforme, Stevens Johnson syndrome, and toxic epidermal necrolysis reported after vaccination, 1999-2017

BACKGROUND

Since the last review of vaccine safety surveillance data for erythema multiforme (EM), Stevens Johnson syndrome (SJS), SJS/TEN, and toxic epidermal necrolysis (TEN) (EM/SJS/TEN), over 37 new vaccines have been introduced in the United States. We sought to describe reported EM/SJS/TEN after vaccines during 1999-2017.

METHODS

We identified U.S. reports of EM/SJS/TEN received by the Vaccine Adverse Event Reporting System (VAERS) during 1999-2017. We stratified analysis by condition (EM, SJS, or TEN), and analyzed reports by serious or non-serious status, sex, age group, time from vaccination to symptom onset, exposure to known causes of EM/SJS/TEN, and vaccines administered. We used Empirical Bayesian data mining to detect vaccine-AE pairs reported more frequently than expected.

RESULTS

Of 466,027 reports to VAERS during 1999-2017, we identified 984 reports of EM, 89 reports of SJS, 6 reports of SJS/TEN, and 7 reports of TEN. Few reports of EM (9%), and most reports of SJS (52%), SJS/TEN (100%), and TEN (100%) were serious. Overall, 55% of reports described males, 48% described children aged < 4 years; 58% of EM/SJS/TEN occurred ≤ 7 days after vaccination. Few reports (≤5%) described exposure to known causes of EM/SJS/TEN. Overall, childhood vaccines (e.g., combined measles, mumps, and rubella vaccine) were most commonly reported. We identified 6 deaths; 4 were exposed to medications associated with EM/SJS/TEN. EM after smallpox vaccine was reported disproportionately among people aged 19-49 years.

CONCLUSIONS

EM/SJS/TEN were rarely reported after vaccination; data mining identified a known association between EM and smallpox vaccine.

Field evaluation of the safety and compatibility of a combined vaccine against porcine parvovirus 1 and porcine reproductive and respiratory syndrome virus in breeding animals

BACKGROUND

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine parvovirus 1 (PPV1) are two common causes of reproductive failure. ReproCyc® ParvoFLEX is a novel subunit vaccine based on the protective viral protein (VP) 2 of PPV1 that has been recently licensed in the European (EU) market, whereas ReproCyc® PRRS EU is a porcine reproductive and respiratory syndrome (PRRS) modified live virus (MLV) vaccine authorized in 2015. The present work sought to evaluate the safety and compatibility of the combined administration of the abovementioned vaccines in target animals under the context of a field PRRSV (experiment A) and PPV1 (experiment B) infection. To achieve this objective, safety and lack of vaccines' antigen interference were established according to the absence of significant differences between the combined vaccinated animals (PPRSV+PPV1) and the single vaccinated animals against PRRSV or PPV1. In both experiments, gilts and sows were evaluated for local and systemic reactions after vaccination as well as for reproductive and productive performance. In addition, tissues from abortions, mummified fetuses and stillborn piglets were analyzed for the presence of PRRSV and PPV1. Lastly, serology and viremia were determined in experiment B.

RESULTS

No relevant differences in terms of safety, reproductive and productive performance between the single vaccinated and the combined vaccinated animals in either experiment were observed.

CONCLUSIONS

ReproCyc® PRRS EU mixed with ReproCyc® ParvoFLEX can be used as a safe method of protection against the detrimental effects of PRRSV and PPV1 infections in breeding female pigs in one single injection. The present results also open up opportunities to tackle reproductive problems as a whole by combining control programs against swine reproductive pathogens.

Safety profile of rubella vaccine administered to pregnant women: A systematic review of pregnancy related adverse events following immunisation, including congenital rubella syndrome and congenital rubella infection in the foetus or infant

BACKGROUND

Data on the safety of inadvertent rubella vaccination in pregnancy is important for rubella vaccination programs aimed at preventing congenital rubella syndrome.

METHODS

The association between monovalent rubella or combination vaccinations in or shortly before pregnancy and potential harm to the foetus was examined by conducting a systematic review and meta-analysis using fixed effect methods and simulation.

RESULTS

Four cohort studies of inadvertently vaccinated and unvaccinated women were found, 15 cohorts of pregnant women who were rubella susceptible at time of inadvertent vaccination and 9 cohort studies with no information on susceptibility and case series. No case of vaccine associated congenital rubella syndrome (CRS) was identified. Cohort studies with an unvaccinated comparison group were limited in number and size, and based on these only a theoretical additional risk of 6 or more cases of CRS per 1000 vaccinated women (0% observed, upper 95% CI 0.6%) could be excluded. Based on cohorts of vaccinated rubella susceptible pregnant women a maximum theoretical risk of 1 CRS case in 1008 vaccinated women (0% observed, upper 95% CI 0.099%) was estimated. Asymptomatic rubella vaccine virus infection of the neonate was also noted (fixed effects estimate of risk overall 1.74%, 95% CI 1.21, 2.28).

CONCLUSION

There is no evidence that CRS is caused by rubella-containing vaccines but transplacental vaccine virus infection can occur. CRS is effectively prevented by vaccination, thus the risk/benefit balance is unequivocally in favour of vaccination. The data confirm previous recommendations that inadvertent vaccination during pregnancy is not an indication for termination of pregnancy.