In the heat of a signal: Responding to a vaccine safety signal for febrile seizures after 2010–11 influenza vaccine in young children, United States

A narrative review of vaccine pharmacovigilance during mass vaccination campaigns: Focus on myocarditis and pericarditis after COVID-19 mRNA vaccination

Vaccines have had a tremendous impact on reducing the burden of infectious diseases; however, they have the potential to cause adverse events following immunization (AEFIs). Prelicensure clinical trials are limited in their ability to detect rare AEFIs that may occur in less than one per thousand individuals. While postmarketing surveillance systems have shown COVID-19 mRNA vaccines to be safe, they led to the identification of rare cases of myocarditis and pericarditis after COVID-19 vaccination that were not initially detected in clinical trials. In this narrative review, we highlight concepts of vaccine pharmacovigilance during mass vaccination campaigns and compare the approaches used in the context of myocarditis and pericarditis following COVID-19 vaccination to historical examples. We describe mechanisms of passive and active surveillance, their strengths and limitations, and how they interacted to identify and characterize the safety signal of myocarditis and pericarditis after COVID-19 mRNA vaccination. Articles were synthesized from a PubMed search using relevant keywords for articles published on vaccine surveillance systems and myocarditis and pericarditis after COVID-19 vaccination, as well as the authors' collections of relevant publications and grey literature reports. The global experience around the identification and monitoring of myocarditis and pericarditis after COVID-19 mRNA vaccination has provided important lessons for vaccine safety surveillance and highlighted its importance in maintaining public trust in mass vaccination programmes in a pandemic context.

Challenges in implementing yearly enhanced safety surveillance of influenza vaccination in Europe: lessons learned and future perspectives

Seasonal influenza vaccines are frequently reformulated, leading to specific challenges for continuous benefit/risk monitoring. In 2014, the European Medicines Agency started requiring annual enhanced safety surveillance (ESS). This article provides a perspective on ESS studies conducted ever since and aims to map existing initiatives used to monitor adverse events following influenza immunization. Of 11 ESS studies, reporting surveillance data of at least five different vaccine brands during four seasons, all were able to rapidly capture vaccine-specific adverse events of interest reports. However, challenges have been identified during study implementation, including recruitment of sufficient participants, enrolling younger age groups, collecting data of vaccine batch numbers, comparing observed with expected rates and achieving adequate return of reported events. Harmonizing safety monitoring standards across countries, and bridging between routine pharmacovigilance and ESS, is likely to allow more comprehensive assessments of influenza vaccine safety, requiring close collaboration between regulators, public health, and manufacturers.

Safety of 9-valent human papillomavirus vaccine administration among pregnant women: Adverse event reports in the Vaccine Adverse Event Reporting System (VAERS), 2014-2017

INTRODUCTION

9-valent human papillomavirus vaccine (9vHPV) was approved by the Food and Drug Administration (FDA) in December 2014. 9vHPV is not recommended during pregnancy, but some women of childbearing age may be inadvertently exposed. This study aims to evaluate reports submitted to the Vaccine Adverse Event Reporting System (VAERS) of pregnant women exposed to 9vHPV.

METHODS

We searched the VAERS database, a national post-licensure vaccine safety surveillance system, for reports of pregnant women vaccinated with 9vHPV in the United States between December 10, 2014 and December 31, 2017. Disproportionate reporting of adverse events (AEs) was assessed using proportional reporting ratios (PRRs).

RESULTS

A total of 82 pregnancy reports were identified. Sixty reports (73.2%) did not describe an AE and were submitted only to report the vaccine exposure during pregnancy. The most frequently reported pregnancy-specific AE was spontaneous abortion (n = 3; 3.7%), followed by vaginal bleeding (n = 2; 2.4%). Among non-pregnancy-specific AEs, injection site reaction (n = 3; 3.7%) was most common. No disproportionate reporting of any AE was found.

DISCUSSION

No unexpected AEs were observed among these pregnancy reports.

Allergic adverse events following 2015 seasonal influenza vaccine, Victoria, Australia

Australia was alerted to a possible increase in allergy-related adverse events following immunisation (AEFI) with 2015 seasonal trivalent influenza vaccines (TIV) by the Victorian state vaccine safety service, SAEFVIC. We describe SAEFVIC’s initial investigation and upon conclusion of the 2015 influenza vaccination programme, to define the signal event and implications for vaccine programmes. Allergy-related AEFI were defined as anaphylaxis, angioedema, urticaria or generalised allergic reaction. Investigations compared 2015 TIV AEFI reports to previous years as proportions and reporting risk (RR) per 100,000, stratified by influenza vaccine brand. The initial investigation showed an increased proportion of allergy-related AEFI compared with 2014 (25% vs 12%), predominantly in adults, with insufficient clinical severity to alter the programme risk-benefit. While overall TIV AEFI RR in 2015 was similar to previous years (RR: 1.07, 95% confidence interval (CI): 0.88–1.29), we identified a near-doubling RR for allergy-related AEFI in 2015 (RR: 1.78, 95% CI: 1.14­– 2.80) from 2011 to 2014 with no difference by vaccine brand or severity increase identified. This increase in generalised allergy-related AEFI, across all used vaccine brands, supports evidence of variable reactogenicity arising from influenza vaccine strain variations. This investigation underlines the importance of effective seasonal influenza vaccine pharmacovigilance.

Surveillance systems and methods for monitoring the post-marketing safety of influenza vaccines at the Centers for Disease Control and Prevention

INTRODUCTION

Annual influenza vaccine safety monitoring is an important component of the influenza vaccination program in the United States to ensure that vaccines are safe, which is important for maintaining public trust in the national vaccination program. This is specially the case for influenza vaccines since the antigen composition of the viruses of which the vaccine is made often changes from one season to the next, based on the circulating strain of influenza virus.

AREAS COVERED

This review describes the two surveillance systems used by the Centers for Disease Control and Prevention (CDC) to monitor the safety of influenza vaccines: 1) the Vaccine Adverse Event Reporting System (VAERS); and 2) the Vaccine Safety datalink (VSD).

EXPERT OPINION

VAERS and VSD are used routinely to monitor the safety of influenza vaccines in the United States, and over the years they have demonstrated their value in monitoring vaccine safety since their implementation in 1990. Both systems, although different, complemented each other well to study febrile seizures in young children following influenza vaccination during the 2010-2011 influenza season. Other examples of potential safety concerns after influenza vaccines are also presented and discussed.

Febrile Seizure Risk After Vaccination in Children 6 to 23 Months

BACKGROUND AND OBJECTIVE

An increased risk of febrile seizure (FS) was identified with concomitant administration of trivalent inactivated influenza vaccine (IIV3) and pneumococcal conjugate vaccine (PCV) 13-valent during the 2010-2011 influenza season. Our objective was to determine whether concomitant administration of IIV3 with other vaccines affects the FS risk.

METHODS

We examined the risk of FS 0 to 1 day postvaccination for all routinely recommended vaccines among children aged 6 through 23 months during a period encompassing 5 influenza seasons (2006-2007 through 2010-2011). We used a population-based self-controlled risk interval analysis with a control interval of 14 to 20 days postvaccination. We used multivariable regression to control for receipt of concomitant vaccines and test for interaction between vaccines.

RESULTS

Only PCV 7-valent had an independent FS risk (incidence rate ratio [IRR], 1.98; 95% confidence interval [CI], 1.00 to 3.91). IIV3 had no independent risk (IRR, 0.46; 95% CI, 0.21 to 1.02), but risk was increased when IIV3 was given with either PCV (IRR, 3.50; 95% CI, 1.13 to 10.85) or a diphtheria-tetanus-acellular-pertussis (DTaP)-containing vaccine (IRR, 3.50; 95% CI, 1.52 to 8.07). The maximum estimated absolute excess risk due to concomitant administration of IIV3, PCV, and DTaP-containing vaccines compared with administration on separate days was 30 FS per 100 000 persons vaccinated.

CONCLUSIONS

The administration of IIV3 on the same day as either PCV or a DTaP-containing vaccine was associated with a greater risk of FS than when IIV3 was given on a separate day. The absolute risk of postvaccination FS with these vaccine combinations was small.

Vaccines and febrile seizures

Vaccine administration is the second leading cause of febrile seizures (FS). FS occurrence in children is a serious concern because it leads to public apprehension of vaccinations. This review discusses the clinical implications of FS, its potential link to vaccinations and its impact on official recommendations for vaccinations in children. Vaccines such as the pertussis antigen-containing vaccine, the measles-containing vaccine and the influenza vaccine have been linked to FS. However, FS events are very rare and are not usually associated with downstream complications or severe neurologic diseases. Considering their significant health benefits, vaccinations have not been restricted in the pediatric population. Nevertheless, vaccine-induced FS could be a problem, particularly in genetically predisposed children. Therefore, post-marketing surveillance studies are required to accurately assess the incidence of FS and identify individuals who are particularly susceptible to FS after vaccination.

Risk of fever after pediatric trivalent inactivated influenza vaccine and 13-valent pneumococcal conjugate vaccine

IMPORTANCE

An observational study found an increased risk of febrile seizure on the day of or 1 day after vaccination (days 0-1) with trivalent inactivated influenza vaccine (TIV) in the 2010-2011 season; risk was highest with simultaneous vaccination with TIV and 13-valent pneumococcal vaccine (PCV13) in children who were 6 to 23 months old. Text messaging is a novel method for surveillance of adverse events after immunization that has not been used for hypothesis-driven vaccine safety research.

OBJECTIVE

To prospectively evaluate whether children receiving TIV and PCV13 simultaneously had higher rates of fever on days 0 to 1 than those receiving either product without the other.

DESIGN, SETTING, AND PARTICIPANTS

Prospective observational cohort study of parents of children 6 to 23 months old recruited from 3 medical center-affiliated clinics in New York City from November 1, 2011, through April 5, 2012. A total of 530 of 614 eligible participants (86.3%) were enrolled. Parents were texted on the night of vaccination (day 0) and the 7 subsequent nights (days 1-7) to report their child's temperature. We used log-binomial regression to calculate adjusted relative risks (aRRs) and excess risk for fever on days 0 to 1, adjusted for age group, past influenza vaccination and simultaneous receipt of selected inactivated vaccines.

EXPOSURES

Receipt of TIV and/or PCV13.

MAIN OUTCOME(S) AND MEASURE(S)

Temperature of 38°C or higher on days 0 to 1 after vaccination.

RESULTS

On days 0 to 1, children receiving TIV and PCV13 simultaneously had higher rates (37.6%) of fever (temperature ≥38°C) than those receiving TIV (7.5%; aRR, 2.69; 95% CI, 1.30-5.60) or PCV13 (9.5%; aRR, 2.67; 95% CI, 1.25-5.66). The excess risk of fever after TIV and PCV13 was 20 and 23 per 100 vaccinations compared with TIV without PCV13 and PCV13 without TIV, respectively. Fever rates for days 2 to 7 were similar across groups. For days 0 to 1, 74.8% of the text messages were confirmed delivered; for another 9.0%, delivery status was unknown. Response rates were 95.1% and 90.9% for days 0 and 1 for confirmed delivered messages, respectively.

CONCLUSIONS AND RELEVANCE

Simultaneous TIV and PCV13 administration was associated with higher transient increased fever risk than administration of either vaccine without the other product. Text messaging to prospectively assess a specific vaccine adverse event has potential for enhancing prelicensure and postlicensure monitoring of adverse events after immunization and deserves further study.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01467934.

Absence of associations between influenza vaccines and increased risks of seizures, Guillain-Barré syndrome, encephalitis, or anaphylaxis in the 2012-2013 season

PURPOSE

We conducted weekly surveillance for pre-specified adverse events following receipt of the 2012-2013 influenza vaccines in the Vaccine Safety Datalink (VSD).

METHODS

For each outcome, risk intervals (i.e., period after vaccination with a potentially increased risk) were defined on the basis of biologic plausibility and prior literature. Seizures following inactivated influenza vaccine (IIV) were monitored in children in three age groups (6-23 months, 24-59 months, and 5-17 years) using a self-controlled risk interval design. We also monitored for Guillain-Barré syndrome, encephalitis, and anaphylaxis following IIV in patients ≥6 months of age using a cohort design with historical controls. In the risk intervals following live attenuated influenza vaccine (LAIV), we collected weekly counts of Guillain-Barré syndrome, encephalitis, and anaphylaxis in patients ages 2-49. Among LAIV vaccinees, numbers of expected events based on rates in historical controls were calculated, adjusted for age and site.

RESULTS

At the end of surveillance, approximately 3.6 million first doses of IIV and 250 000 first doses of LAIV had been administered in the VSD. No elevated risks were identified in risk intervals following 2012-2013 IIV, as compared with a self-matched control interval or to historical controls. For each outcome, fewer than three events occurred in the risk interval following 2012-2013 LAIV, and we thus were unable to estimate measures of relative risks.

CONCLUSIONS

No increased risk was identified for any of the pre-specified outcomes following 2012-2013 influenza vaccinations in the VSD. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Healthcare providers' knowledge, experience and challenges of reporting adverse events following immunisation: a qualitative study

Background

Healthcare provider spontaneous reporting of suspected adverse events following immunisation (AEFI) is central to monitoring post-licensure vaccine safety, but little is known about how healthcare professionals recognise and report to surveillance systems. The aim of this study was explore the knowledge, experience and attitudes of medical and nursing professionals towards detecting and reporting AEFI.

Methods

We conducted a qualitative study, using semi-structured, face to face interviews with 13 Paediatric Emergency Department consultants from a tertiary paediatric hospital, 10 General Practitioners, 2 local council immunisation and 4 General Practice nurses, recruited using purposive sampling in Adelaide, South Australia, between December 2010 and September 2011. We identified emergent themes related to previous experience of an AEFI in practice, awareness and experience of AEFI reporting, factors that would facilitate or impede reporting and previous training in vaccine safety. Thematic analysis was used to analyse the data.

Results

AEFI reporting was infrequent across all groups, despite most participants having reviewed an AEFI. We found confusion about how to report an AEFI and variability, according to the provider group, as to the type of events that would constitute a reportable AEFI. Participants’ interpretation of a “serious” or “unexpected” AEFI varied across the three groups. Common barriers to reporting included time constraints and unsatisfactory reporting processes. Nurses were more likely to have received formal training in vaccine safety and reporting than medical practitioners.

Conclusions

This study provides an overview of experience and beliefs of three healthcare professional groups in relation to identifying and reporting AEFI. The qualitative assessment reveals differences in experience and awareness of AEFI reporting across the three professional groups. Most participants appreciated the importance of their role in AEFI surveillance and monitoring the ongoing safety of vaccines. Future initiatives to improve education, such as increased training to health care providers, particularly, medical professionals, are required and should be included in both undergraduate curricula and ongoing, professional development.