Adverse Events Following Immunization With mRNA and Viral Vector Vaccines in Individuals With Previous Severe Acute Respiratory Syndrome Coronavirus 2 Infection From the Canadian National Vaccine Safety Network.

BACKGROUND: Adults previously infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop short-term immunity and may have increased reactogenicity to coronavirus disease 2019 (COVID-19) vaccines. This prospective, multicenter, active-surveillance cohort study examined the short-term safety of COVID-19 vaccines in adults with a prior history of SARS-CoV-2. METHODS: Canadian adults vaccinated between 22 December 2020 and 27 November 2021 were sent an electronic questionnaire 7 days post-dose 1, dose 2, and dose 3 vaccination. The main outcome was health events occurring in the first 7 days after each vaccination that prevented daily activities, resulted in work absenteeism, or required a medical consultation, including hospitalization. RESULTS: Among 684 998 vaccinated individuals, 2.6% (18 127/684 998) reported a prior history of SARS-CoV-2 infection a median of 4 (interquartile range: 2-6) months previously. After dose 1, individuals with moderate (bedridden) to severe (hospitalized) COVID-19 who received BNT162b2, mRNA-1273, or ChAdox1-S vaccines had higher odds of a health event preventing daily activities, resulting in work absenteeism or requiring medical consultation (adjusted odds ratio [95% confidence interval]: 3.96 [3.67-4.28] for BNT162b2, 5.01 [4.57-5.50] for mRNA-1273, and 1.84 [1.54-2.20] for ChAdox1-S compared with no infection). Following dose 2 and 3, the greater risk associated with previous infection was also present but was attenuated compared with dose 1. For all doses, the association was lower or absent after mild or asymptomatic infection. CONCLUSIONS: Adults with moderate or severe previous SARS-CoV-2 infection were more likely to have a health event sufficient to impact routine activities or require medical assessment in the week following each vaccine dose.

mRNA COVID-19 vaccine safety among older adults from the Canadian National Vaccine Safety Network.

This study examined short-to-medium term safety of COVID-19 vaccines among adults aged ≥65 years using the Canadian National Vaccine Safety Network active safety surveillance data. Both vaccinated and unvaccinated older adult participants recruited from seven provinces and territories were included in the analysis. Safety was assessed at 7 days after COVID-19 vaccination (dose 1, 2 and 3), and 7 months after dose 1. Multivariable logistic regression was used to examine the association between BNT162b2/mRNA-1273 COVID-19 vaccines and two short-term health events: 1) health event preventing daily activities and/or required medical consultation, 2) serious health events resulting in an emergency department visit and/or hospitalization within 7 days following each dose. We also assessed the rates of serious health events for the period between dose 1 and 2, and 7-months following dose 1. Between December 2020 and February 2022, a total of 173,038, 104,452, and 13,970 older adults completed dose 1, dose 2, and dose 3 surveys, respectively. The control survey was completed by 2,955 unvaccinated older adults. Health events occurred more frequently among recipients after dose 2 homologous mRNA-1273 (adjusted odds ratio [95 % confidence interval]: 2.91 [2.24-3.79]) and dose two heterologous (BNT162b2 followed by mRNA-1273): 1.50 [1.12-2.02] compared to unvaccinated counterparts. There was no difference in event rates after any dose of BNT162b2 and unvaccinated participants. The rates of serious health events following COVID-19 vaccination were very low (≤0.3 %) across all vaccine products and doses, and were not higher compared to unvaccinated controls, and were not associated with an emergency department visit or hospitalization within 7 days following vaccination. Reported symptoms were self-limited and rarely required medical assessment. Our findings further strengthen the current evidence that mRNA COVID-19 vaccines are safe and can be used to inform older adults about expected adverse events following COVID-19 vaccination.

Immune thrombocytopenic purpura and Guillain-Barré syndrome after 23-valent pneumococcal polysaccharide vaccination in Japan: The vaccine effectiveness, networking, and universal safety (VENUS) study.

BACKGROUND: To address the lack of an active vaccine safety surveillance system in Japan, the Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study was initiated in 2021 as a pilot system using existing health insurance claims data and vaccination records. METHODS: This study evaluated the value of the VENUS study by assessing the incidence of immune thrombocytopenic purpura (ITP) and Guillain-Barré syndrome (GBS) following vaccination with the 23-valent pneumococcal polysaccharide vaccine (PPSV23) using a self-controlled case series (SCCS) design. RESULTS: Incidence rate ratios for ITP during 28-day and 42-day risk periods were 0.89 (95% confidence interval [CI], 0.12-6.4), and 0.58 (95% CI, 0.081-4.2), respectively. Neither was statistically significant. Incidence rate ratios could not be estimated for GBS due to the limited sample size. CONCLUSION: The VENUS study can provide valuable insights to facilitate the establishment of an advanced vaccine monitoring system in Japan.

Unpacking adverse events and associations post COVID-19 vaccination: a deep dive into vaccine adverse event reporting system data.

INTRODUCTION: The rapid development of COVID-19 vaccines has provided crucial tools for pandemic control, but the occurrence of vaccine-related adverse events (AEs) underscores the need for comprehensive monitoring. METHODS: This study analyzed the Vaccine Adverse Event Reporting System (VAERS) data from 2020-2022 using statistical methods such as zero-truncated Poisson regression and logistic regression to assess associations with age, gender groups, and vaccine manufacturers. RESULTS: Logistic regression identified 26 System Organ Classes (SOCs) significantly associated with age and gender. Females displayed especially higher odds in SOC 19 (Pregnancy, puerperium and perinatal conditions), while males had higher odds in SOC 25 (Surgical and medical procedures). Older adults (>65) were more prone to symptoms like Cardiac disorders, whereas those aged 18-65 showed susceptibility to AEs like Skin and subcutaneous tissue disorders. Moderna and Pfizer vaccines induced fewer SOC symptoms compared to Janssen and Novavax. The zero-truncated Poisson regression model estimated an average of 4.243 symptoms per individual. CONCLUSION: These findings offer vital insights into vaccine safety, guiding evidence-based vaccination strategies and monitoring programs for precise and effective outcomes.

Adverse events following mRNA SARS-CoV-2 vaccination among U.S. nursing home residents.

BACKGROUND: The devastating impact of the SARS-CoV-2 pandemic prompted the development and emergency use authorization of two mRNA vaccines in early 2020. Vaccine trials excluded nursing home (NH) residents, limiting adverse event data that directly apply to this population. METHODS: To prospectively monitor for potential adverse events associated with vaccination, we used Electronic Health Record (EHR) data from Genesis HealthCare, the largest NH provider in the United States. EHR data on vaccinations and pre-specified adverse events were updated daily and monitored for signal detection among residents of 147 facilities who received the first dose of vaccine between December 18, 2020 and January 3, 2021. For comparison, unvaccinated residents during the same time period were included from 137 facilities that started vaccinating at least 15 days after the vaccinating-facilities. RESULTS: As of January 3, 2021, 8553 NH residents had received one dose of SARS-CoV-2 vaccine and by February 20, 2021, 8371 residents had received their second dose of vaccine; 11,072 were included in the unvaccinated comparator group. No significant associations were noted for neurologic outcomes, anaphylaxis, or cardiac events. CONCLUSIONS: No major safety problems were detected following the first or second dose of the vaccine to prevent COVID-19 in the study cohort from December 18, 2020 through March 7, 2021.

Safety of pentavalent DTaP-IPV/Hib combination vaccine in post-marketing surveillance in Guangzhou, China, from 2011 to 2017.

BACKGROUND: The DTaP-IPV/Hib combination vaccine can replace the acellular tetanus vaccine, polio vaccine, and the Haemophilus influenzae type B vaccine. Data on the safety of DTaP-IPV/Hib vaccines are required. We aimed to evaluate the safety of the vaccination program. METHODS: Using the National Adverse Events Following Immunization (AEFI) surveillance system (CNAEFIS) in Guangzhou, China, a retrospective study was performed from May 11, 2011, to December 31, 2017. There were 376 cases of adverse events after vaccination with the DTaP IPV/Hib vaccine. The primary analysis indicators were the number of vaccines used, the number of AEFI reports received, and the reporting rate (per 100,000). RESULTS: From May 1, 2011, to December 31, 2017, 516,000 doses of vaccine were inoculated, and 376 cases of adverse reactions were reported; the reporting rate was 72.8 per 100,000 vaccines. There were eight cases of serious AEFIs (1.5 per 100,000), with four cases of thrombocytopenic purpura (0.8 per 100,000); three cases of cyanosis of the lips, stiffness, and flexion of limbs, and convulsions (0.6 per 100,000); and one case of a high fever (0.2 per 100,000). The highest incidence of AEFIs occurred after the fourth dose (n = 207, 55.0%, 40.1 per 100,000), followed by the first dose (n = 81, 21.5%, 15.7 per 100,000), second dose (n = 48, 12.8%, 9.3 per 100,000) and third dose (n = 40, 10.6%, 7.7 per 100,000). The AEFI incidence was higher after injection of the vaccine into the deltoid muscle of the upper arm (n = 276, 73.4%, 53.5 per 100,000) than after injection of the vaccine into the thigh (n = 100, 26.6%, 19.4 per 100,000). There was a significant difference between AEFIs after injection into the deltoid of the upper arm deltoid and the thigh (x2 = 164.8, P < 0.05). CONCLUSIONS: Most of the reported AEFIs after DTaP-IPV/Hib vaccination are not serious. There were four cases of TP in this study; vaccination may be a rare cause of thrombocytopenic purpura.

On the contextual nature of vaccine safety monitoring: Adverse events reporting after HPV-vaccination in Denmark, 2015.

BACKGROUND: In 2013-15, Denmark experienced an increase in reported suspected adverse events following vaccination (AEFI) against human papilloma virus (HPV). Dedicated centres ("One Access") were established in order to standardize management of patients who experienced medically unexplained physical symptoms after HPV vaccination. Since One Access was targeted patients with suspected AEFI after HPV vaccination, we used this opportunity to estimate completeness in AEFI reporting to the Danish Medicines Agency (DMA), and explore the topic of AEFI reporting from the perspective of physicians working at the centres to better understand health professionals' reporting behaviour. METHODS: The study consisted of a quantitative and a qualitative part. In the quantitative analysis, we used the Danish civil registry number to merge a line-list of all One Access patients referred in 2015 with total number of patients who had reported suspected serious AEFI following HPV vaccination to the DMA in the years 2009-2015. We conducted four semi-structured interviews with doctors representing three out of five regions. The Theoretical Domains Framework together with empirical data from two clinical fieldtrips guided the formation of the qualitative study. RESULTS: Among 1577 One Access patients, only 404 (26%) were reported to the DMA. We found significant regional differences in reporting completeness (p < 0.001) and differences between regions when looking at reporters' backgrounds (healthcare professionals vs non-professionals; p = 0.004). We identified several factors of importance for reporting behaviour amongst physicians, mainly under the domains of Knowledge, Motivation & Goals, and Environmental Context. CONCLUSIONS: Despite an official aim of homogenous case management, reporting of suspected AEFI was incomplete with large regional differences. The qualitative study corroborated that reporting behaviour was contextual. This observation represents an important caveat in interpreting data from AEFI reporting, in particular when these data are used for research or policymaking.

Vaccine monitoring systems: A potential model for medications in pregnancy.

Multiple vaccine safety systems contribute to monitor and assess the safety of vaccines given to pregnant women and their offspring. This article presents a review of the strengths and limitations of several national vaccine safety systems. The review concludes that the present framework of vaccine safety systems offers lessons to be learned toward the design of a system for monitoring and assessing the safety of medications administered to pregnant women in clinical practice and research.

An algorithm developed using the Brighton Collaboration case definitions is more efficient for determining diagnostic certainty.

The Brighton Collaboration is a global research network focused on vaccine safety. The Collaboration has created case definitions to determine diagnostic certainty for several adverse events. Currently nested within multi-page publications, these definitions can be cumbersome for use. We report the results of a randomized trial in which the case definition for anaphylaxis was converted into a user-friendly algorithm and compared the algorithm with the standard case definition. The primary outcomes were efficiency and accuracy. Forty medical students determined the Brighton Level of diagnostic certainty of a sample case of anaphylaxis using either the algorithm or the original case definition. Most participants in both groups selected the correct Brighton Level. Participants using the algorithm required significantly less time to review the case and determine the level of diagnostic certainty [mean difference=107 s (95% CI: 13-200; p=0.026)], supporting that the algorithm was more efficient without impacting accuracy.