Demonstration of background rates of three conditions of interest for vaccine safety surveillance

Adverse events following Measles-Mumps-Rubella and varicella immunization: A safety profile analysis and comparison of different vaccination schedules based on the Italian Pharmacovigilance Network in the Veneto Region

Objective

The vaccines for measles, mumps, rubella and varicella (MMR and V) have been mandatory in Italy since 2017. Two different vaccination strategies are suggested for the first dose: trivalent MMR and a separate V vaccine or the tetravalent MMRV vaccine. Our aim is to compare the safety profile of MMRV and MMR-V vaccines through the passive adverse event reporting system in the Veneto region and to perform a case-by-case review of a few conditions of interest (febrile and afebrile seizures, ataxia, encephalitis, Guillain-Barré Syndrome, thrombocytopenia, neutropenia and Henoch-Schönlein Purpura). Age and sex differences were also explored.

Methods

We identified all reports following MMRV or MMR-V vaccination in the Veneto Region and received into the National Pharmacovigilance Network between 2007 and April 30, 2022.

Results

9,510 reports were retrieved, of which 5,662 (59.5 %) were related to MMRV and 3,848 (40.5 %) to MMR-V. No safety signals were detected supporting the evidence that MMRV and MMR-V vaccinations have a good safety profile. The reporting rate (RR) for serious events between 2007 and 2022 resulted in 13.67 per 10,000 administered doses for MMRV and 10.90 for MMR-V.

Conclusion

Passive surveillance data show a significantly higher rate of serious events for males 0-2 years old, both overall and stratified per vaccination strategy. Further studies are needed to confirm this observation. The analyses suggest that retrieved differences do not have a significant impact on the overall safety of both formulations.

COVID-19 vaccine safety: Background incidence rates of anaphylaxis, myocarditis, pericarditis, Guillain-Barré Syndrome, and mortality in South Korea using a nationwide population-based cohort study

BACKGROUND

To properly assess an association between vaccines and specific adverse events requires a comparison between the observed and background rates; however, studies in South Korea are currently limited. Therefore, in this study, we estimated the background incidence of anaphylaxis, myocarditis, pericarditis, Guillain-Barré syndrome (GBS), and mortality in South Korea.

METHODS

A retrospective cohort study was conducted using the National Sample Cohort (NSC) data. Using NSC, the background incidence rate was estimated by dividing the number of episodes during 2009-2019 by the total population by year and then multiplying by 100,000. Using Statistics Korea data, the background mortality rate was estimated by dividing the number of deaths, during 2009-2019 by the standard population for that year and then multiplying by 100,000. Using background mortality rates, we predicted mortality rates for 2021 using autoregressive integrated moving average models. Further, the expected mortality rates were compared with observed mortality rates.

RESULTS

The age-adjusted incidence rate (AIR) of anaphylaxis increased from 4.28 to 22.90 cases per 100,000 population (p = 0.003); myocarditis showed no significant increase, changing from 0.56 to 1.26 cases per 100,000 population (p = 0.276); pericarditis increased from 0.94 to 1.88 cases per 100,000 population (p = 0.005); and GBS increased from 0.78 to 1.21 cases per 100,000 population (p = 0.013). The age-adjusted mortality rate decreased from 645.24 to 475.70 deaths per 100,000 population (p <0.001). The 2021 observed/expected mortality rates for overall (ratio: 1.08, 95% confidence interval [CI]: 1.07-1.08), men (ratio: 1.07, 95% CI: 1.07-1.08), and women (ratio: 1.08, 95% CI: 1.07-1.09), were all significantly higher. When stratified by age group, those aged ≥80 (ratio: 1.16, 95% CI: 1.15-1.17), 60-69 (ratio: 1.11, 95% CI: 1.10-1.13), and 20-29 years old (ratio: 1.07, 95% CI: 1.02-1.13) were also significantly higher.

CONCLUSION

Through the estimation of background rates related to anaphylaxis, myocarditis, pericarditis, GBS, and mortality, we established a reference point for evaluating the potential excess occurrence of adverse events following COVID-19 vaccination. This reference point serves as substantive evidence supporting the safety profile of COVID-19 vaccines.

Background incidence rates of adverse events of special interest related to COVID-19 vaccines in Ontario, Canada, 2015 to 2020, to inform COVID-19 vaccine safety surveillance

Background

Background incidence rates are critical in pharmacovigilance to facilitate identification of vaccine safety signals. We estimated background incidence rates of 11 adverse events of special interest related to COVID-19 vaccines in Ontario, Canada.

Methods

We conducted a population-based retrospective observational study using linked health administrative databases for hospitalizations and emergency department visits among Ontario residents. We estimated incidence rates of Bell’s palsy, idiopathic thrombocytopenia, febrile convulsions, acute disseminated encephalomyelitis, myocarditis, pericarditis, Kawasaki disease, Guillain-Barré syndrome, transverse myelitis, acute myocardial infarction, and anaphylaxis during five pre-pandemic years (2015–2019) and 2020.

Results

The average annual population was 14 million across all age groups with 51% female. The pre-pandemic mean annual rates per 100,000 population during 2015–2019 were 191 for acute myocardial infarction, 43.9 for idiopathic thrombocytopenia, 28.8 for anaphylaxis, 27.8 for Bell’s palsy, 25.0 for febrile convulsions, 22.8 for acute disseminated encephalomyelitis, 11.3 for myocarditis/pericarditis, 8.7 for pericarditis, 2.9 for myocarditis, 2.0 for Kawasaki disease, 1.9 for Guillain-Barré syndrome, and 1.7 for transverse myelitis. Females had higher rates of acute disseminated encephalomyelitis, transverse myelitis and anaphylaxis while males had higher rates of myocarditis, pericarditis, and Guillain-Barré syndrome. Bell’s palsy, acute disseminated encephalomyelitis, and Guillain-Barré syndrome increased with age. The mean rates of myocarditis and/or pericarditis increased with age up to 79 years; males had higher rates than females: from 12 to 59 years for myocarditis and ≥12 years for pericarditis. Febrile convulsions and Kawasaki disease were predominantly childhood diseases and generally decreased with age.

Conclusions

Our estimated background rates will permit estimating numbers of expected events for these conditions and facilitate detection of potential safety signals following COVID-19 vaccination.

Trends and Resource Utilization in Kawasaki Disease Hospitalizations in the United States, 2008-2017

OBJECTIVES

To explore trends in hospitalization rate, resource use, and outcomes of Kawasaki Disease (KD) in children in the United States from 2008 to 2017.

METHODS

This was a retrospective, serial cross-sectional analysis of pediatric hospitalizations with International Classification of Disease diagnostic codes for KD in the National Inpatient Sample. Hospitalization rates per 100 000 populations were calculated and stratified by age group, gender, race, and US census region. Prevalence of coronary artery aneurysms (CAA) were expressed as proportions of KD hospitalizations. Resource use was defined in terms of length of stay and hospital cost. Cochran-Armitage and Jonckheere-Terpstra trend tests were used for categorical and continuous variables, respectively. P <.05 was considered significant.

RESULTS

A total of 43 028 pediatric hospitalizations identified with KD, yielding an overall hospitalization rate of 5.5 per 100 000 children. The overall KD hospitalization rate remained stable over the study period (P = .18). Although KD hospitalization rates differed by age group, gender, race, and census region, a significant increase was observed among Native Americans (P = .048). Rates of CAA among KD hospitalization increased from 2.4% to 6.8% (P = .04). Length of stay remained stable at 2 to 3 days, but inflation-adjusted hospital cost increased from $6819 in 2008 to $10 061 in 2017 (Ptrend < 0.001).

CONCLUSIONS

Hospitalization-associated costs and rates of CAA diagnostic codes among KD hospitalizations increased, despite a stable KD hospitalization rate between 2008 and 2017. These findings warrant further investigation and confirmation with databases with granular clinical information.

Adverse events following pediatric immunization in an Indian city

Purpose

Adverse effects are noticeable immediately after vaccination, especially when vaccinated to healthy people at the time of vaccination. The vaccine may cause adverse events which are very rare but adverse event following immunization surveillance becomes correspondingly more important in a less studied population like India. Hence, there is a need for carrying out a study pertaining to vaccine safety in the pediatric population of age 0-12 years and assessing the events occurring post-vaccination.

Materials and Methods

A prospective observational study was conducted in three primary healthcare centers and two tertiary care hospitals for 6 months from April 2016 to September 2016 with a total of 826 children enrolled. Detected adverse events for suspected vaccines were analyzed for causality by the World Health Organization causality assessment instrument. Sex-specific differences in incidences of adverse events were assessed.

Results

The cumulative adverse events were found highest in pentavalent vaccines (510 incidences, 62.04%) followed by the bacillus Calmette-Guérin vaccine (189 incidences, 22.99%). The study didn't reveal any significant association in incidences of adverse events following immunization and sex of the children.

Conclusion

Vaccine safety surveillance studies are need of the hour in developing countries to maintain public trust in vaccines, the ultimate objective being to have vaccines with the most favorable benefit-risk profile. The present study discussed the various adverse events following immunization and suggested the absence of any sex-specific difference in incidences of adverse events in children.