Background rates of adverse events of special interest for COVID-19 vaccines: A multinational Global Vaccine Data Network (GVDN) analysis

Covid-19 Vaccination During Pregnancy in France: a Descriptive Study of Uptake Using the National Healthcare data System

Pregnant women and their fetus are at increased risk of complications when infected by SARS-CoV-2. This study describes COVID-19 vaccine uptake during pregnancy in France (i) according to socio-demographic characteristics, and (ii) over calendar time and pregnancy stages. Using the hospital discharge records of the national healthcare database, we identified women ending pregnancy at hospital between Dec 27, 2020, i.e. beginning of Covid-19 vaccine availability, and Dec 31, 2022. Covid-19 vaccinations and SARS-CoV-2 infections were also available on two specific linked databases. Vaccine coverage was defined as uptake of at least one dose of vaccine during the 2-year study period, or more specifically during one of five phases of pregnancy (first, second and third trimesters, pre-conceptional and post-pregnancy periods). We also defined ineligibility as the six-month period following each Covid-19 infection. We calculated weekly rates of vaccination by pregnancy phase, accounting for ineligibility. About 75% of women received at least one dose of vaccine in 2021-2022 vs. 90% in the general population with a similar age structure. About 26% received at least one dose of vaccine while pregnant. The rate was lower among younger women, deprived women, and those living in the south-east of mainland France or in overseas territories. Weekly vaccination rates according to the phase of pregnancy showed that women mostly received vaccination outside the pregnancy trimesters (after or, to a less extent, before pregnancy). Vaccinations during pregnancy mostly occurred in the second trimester. When only elective terminations were considered, weekly rates of vaccination were almost identical, whatever the pregnancy phase (before, during or after pregnancy). Overall, our results show the positive impact of national recommendations on uptake dynamics. Vaccine coverage in pregnant women could be improved with targeted campaigns.

[COVID-19 vaccine safety: results of active surveillance at a sentinel site in ArgentinaSegurança das vacinas contra COVID-19: resultados da vigilância ativa em uma unidade sentinela da Argentina]

Objective

To analyze the results of surveillance of adverse events of special interest (AESI) within the context of the COVID-19 vaccination campaign at a sentinel site in Argentina. The retrospective (pre-vaccination) period was compared with the prospective (vaccination) period to identify safety signals.

Methods

Retrospective and prospective search for AESI based on ICD-10 hospital discharge codes. A descriptive analysis, moving-averages trend smoothing, and control charts were used to detect changes in AESI behavior.

Results

A total of 1,586 AESI were identified. Analysis of the proportion of AESI codes at hospital discharge revealed an increase during the pandemic period (2020) and a progressive decrease during the vaccination period (2021-2022), accounted for by the incidence of acute respiratory distress syndrome (ARDS). Moving-average smoothing and control charts were compared to identify time points at which the proportion of AESI exceeded the upper limits of control. During the vaccination period, this occurred for ARDS, thrombosis, myocarditis, meningoencephalitis, multisystem inflammatory syndrome, and anaphylaxis. No differences were observed for Guillain-Barré syndrome, thrombocytopenia, or pericarditis. Acute disseminated encephalomyelitis, meningoencephalitis, and pericarditis events during the vaccination period all occurred in subjects with no history of vaccination.

Conclusion

Active sentinel-site surveillance allowed identification of AESI occurring at a higher frequency during the vaccination period compared to the pre-vaccination baseline. The protective effect of the vaccine against COVID -19 was clearly observed, as manifested especially by a reduction of ARDS cases in the post-vaccination period. This strategy is useful for assessing vaccine safety by identification of safety signals.

Nuvaxovid NVX-CoV2373 vaccine safety profile: real-world data evidence after 100,000 doses, Australia, 2022 to 2023

IntroductionNuvaxovid became available in Australia from February 2022, a year after the first COVID-19 vaccines. This protein-based vaccine was an alternative for people who had had an adverse event to and/or were hesitant to receive an mRNA or adenovirus-based COVID-19 vaccine. Although safety from clinical trials was reassuring, small trial populations, low administration rates and limited post-licensure intelligence meant potential rare adverse events were underinformed.AimWe aimed to describe Nuvaxovid's safety profile in a real-world setting.MethodsWe conducted a retrospective observational analysis of adverse events following immunisation (AEFI) spontaneously reported to SAFEVAC, the integrated vaccine safety surveillance system in Victoria and Western Australia. Reports from 14 February 2022 to 30 June 2023 were analysed by vaccinee demographics, reported reactions and COVID-19 vaccine dose, and compared as reporting rates (RR) per 100,000 doses administered.ResultsWe received 356 AEFI reports, following 102,946 Nuvaxovid doses administered. Rates were higher after dose 1 than dose 2 (rate ratio: 1.5, p = 0.0008), primary series than booster (rate ratio: 2.4, p < 0.0001), and in females vs males (rate ratio: 1.4, p = 0.004). Clinically confirmed serious AEFI included 94 cases of chest pain (RR = 91.3), two myocarditis (RR = 1.9) and 20 pericarditis (RR = 19.4). Guillain-Barré syndrome or thrombosis with thrombocytopaenia syndromes were not reported, nor deaths attributable to vaccination.ConclusionSAFEVAC's collaborative data model enabled pooling of clinically reviewed data across jurisdictions, increasing the safety profile evidence for Nuvaxovid and improving the odds for identification and description of rare events. This analysis affirmed the safety profile of Nuvaxovid.

Deaths Related to New-Onset Seizures After Vaccination

Background: Adverse effects following vaccination are well-known. While most effects are mild and transient, some may be severe or even lethal. Particularly with regard to coronavirus disease 2019 (COVID-19) vaccinations, which were "fast-tracked," it is incumbent upon the medical community to be diligent in identifying potential vaccine-associated adverse events so that physicians and patients can make truly informed decisions when considering the risks versus benefits of vaccination. Objective: To provide an in-depth discussion about post-vaccination seizures, particularly with regard to COVID-19 vaccinations. Research Design: Retrospective review of two cases where death was deemed to be the result of new-onset seizures; in each case, the seizures began shortly following vaccination. Subjects: In one case, death was certified by the primary care physician, without implicating the recent COVID-19 vaccination. In the other case, certified by the medical examiner, recent simultaneous vaccination with a COVID-19 vaccine and an influenza vaccine were considered to be contributory to death. Measures: The case specifics are presented for each case, including clinical work-up (both cases) and autopsy findings (one case). Conclusions: When attempting to determine whether or not a seizure-related death is due to a vaccine-induced new-onset seizure disorder, forensic pathologists need to rule-out other explanations for the seizures. Although a temporal association between seizures and vaccination is not sufficient, in and of itself, to prove causality, the temporal association, in combination with the absence of another explanation for seizures, and knowledge of similar cases in the medical literature, is sufficient to ascribe a causal role to the vaccination.

Validation of the newly proposed Brighton Collaboration case definition for vaccine-induced immune thrombocytopenia and thrombosis

Vaccine-induced immune thrombocytopenia and thrombosis (VITT) is a newly recognized syndrome mediated by anti-platelet factor 4 antibodies induced by Covid-19 adenovirus-vectored vaccines including ChAdOx1 nCoV-19 and Ad26.COV2.S. This study validated a proposed Brighton Collaboration case definition for VITT. A data collection form was developed and used to capture the variations in VITT criteria and assess their level of diagnostic certainty from adjudicated positive VITT case datasheets in Germany (n = 71), UK (n = 220), Australia (n = 203), and Taiwan (n = 56). We observed high prevalence of each component of the proposed VITT definition in positive cases (84%-100%), except for the occurrence of thrombosis or thromboembolism criterion in only 34% of VITT cases in Taiwan. The sensitivity of this proposed definition was 100% for Germany and UK, 92% for Australia, and 89% for Taiwan cases. These findings support the validity of this case definition for VITT.

Establishing the Vaccine Safety Health Link: A large, linked data resource for the investigation of vaccine safety concerns

OBJECTIVE

Post-licensure vaccine safety surveillance of adverse events following immunisation is critical to ensure public safety and confidence in vaccines. This paper aims to describe the governance structure and data linkage methodology behind the establishment of the largest linked vaccine safety surveillance data resource in Australia - The Vaccine Safety Health Link (VSHL).

METHODS

The Vaccine Safety Health Link contains linked records from the Australian Immunisation Register with records from hospital, perinatal, mortality, and notifiable disease datasets in near real-time. Linkage is done by the Centre for Victorian Data Linkage who receive the datasets in an identifiable format which then undergo standardisation, enrichment, linkage, quality assurance and de-identification, prior to being supplied for analysis.

RESULTS

The VSHL data resource allows sensitive and rapid analysis of a broad spectrum of suspected adverse events to ensure the safety of all vaccines administered. It is also used to refute spurious concerns where no associations are found, upholding trust, and maintaining vaccine confidence.

CONCLUSIONS

The Vaccine Safety Health Link's surveillance design complements existing vaccine safety surveillance methods. Challenges encountered and lessons learnt using Vaccine Safety Health Link would benefit linkage projects globally.

IMPLICATIONS FOR PUBLIC HEALTH

In its first two years, The Vaccine Safety Health Link has been used for 14 vaccine safety investigations. Studies into these conditions would not have otherwise been possible. The Vaccine Safety Health Link also partners with the Global Vaccine Data Network™ for approved collaborative studies with a combined population of over 300 million people.

COVID-19 vaccines and adverse events of special interest: A multinational Global Vaccine Data Network (GVDN) cohort study of 99 million vaccinated individuals

BACKGROUND

The Global COVID Vaccine Safety (GCoVS) Project, established in 2021 under the multinational Global Vaccine Data Network™ (GVDN®), facilitates comprehensive assessment of vaccine safety. This study aimed to evaluate the risk of adverse events of special interest (AESI) following COVID-19 vaccination from 10 sites across eight countries.

METHODS

Using a common protocol, this observational cohort study compared observed with expected rates of 13 selected AESI across neurological, haematological, and cardiac outcomes. Expected rates were obtained by participating sites using pre-COVID-19 vaccination healthcare data stratified by age and sex. Observed rates were reported from the same healthcare datasets since COVID-19 vaccination program rollout. AESI occurring up to 42 days following vaccination with mRNA (BNT162b2 and mRNA-1273) and adenovirus-vector (ChAdOx1) vaccines were included in the primary analysis. Risks were assessed using observed versus expected (OE) ratios with 95 % confidence intervals. Prioritised potential safety signals were those with lower bound of the 95 % confidence interval (LBCI) greater than 1.5.

RESULTS

Participants included 99,068,901 vaccinated individuals. In total, 183,559,462 doses of BNT162b2, 36,178,442 doses of mRNA-1273, and 23,093,399 doses of ChAdOx1 were administered across participating sites in the study period. Risk periods following homologous vaccination schedules contributed 23,168,335 person-years of follow-up. OE ratios with LBCI > 1.5 were observed for Guillain-Barré syndrome (2.49, 95 % CI: 2.15, 2.87) and cerebral venous sinus thrombosis (3.23, 95 % CI: 2.51, 4.09) following the first dose of ChAdOx1 vaccine. Acute disseminated encephalomyelitis showed an OE ratio of 3.78 (95 % CI: 1.52, 7.78) following the first dose of mRNA-1273 vaccine. The OE ratios for myocarditis and pericarditis following BNT162b2, mRNA-1273, and ChAdOx1 were significantly increased with LBCIs > 1.5.

CONCLUSION

This multi-country analysis confirmed pre-established safety signals for myocarditis, pericarditis, Guillain-Barré syndrome, and cerebral venous sinus thrombosis. Other potential safety signals that require further investigation were identified.

Acute disseminated encephalomyelitis and transverse myelitis following COVID-19 vaccination - A self-controlled case series analysis

Acute Disseminated Encephalomyelitis (ADEM) and Transverse Myelitis (TM) are within the group of immune mediated disorders of acquired demyelinating syndromes. Both have been described in temporal association following various vaccinations in case reports and case series and have been evaluated in observational studies. A recent analysis conducted by The Global Vaccine Data Network (GVDN) observed an excess of ADEM and TM cases following the adenoviral vectored ChAdOx1 nCoV-19 (AZD1222) and mRNA-1273 vaccines, compared with historically expected background rates from prior to the pandemic. Further epidemiologic studies were recommended to explore these potential associations. We utilized an Australian vaccine datalink, Vaccine Safety Health-Link (VSHL), to perform a self-controlled case series analysis for this purpose. VSHL was selected for this analysis as while VSHL data are utilised for GVDN association studies, they were not included in the GVDN observed expected analyses. The VSHL dataset contains vaccination records sourced from the Australian Immunisation Register, and hospital admission records from the Victorian Admitted Episodes Dataset for 6.7 million people. These datasets were used to determine the relative incidence (RI) of G040 (ADEM) and G373 (TM) ICD-10-AM coded admissions in the 42-day risk window following COVID-19 vaccinations as compared to control periods either side of the risk window. We observed associations between ChAdOx1 adenovirus vector COVID-19 vaccination and ADEM (all dose RI: 3.74 [95 %CI 1.02,13.70]) and TM (dose 1 RI: 2.49 [95 %CI: 1.07,5.79]) incident admissions. No associations were observed between mRNA COVID-19 vaccines and ADEM or TM. These findings translate to an extremely small absolute risk of ADEM (0.78 per million doses) and TM (1.82 per million doses) following vaccination; any potential risk of ADEM or TM should be weighed against the well-established protective benefits of vaccination against COVID-19 disease and its complications. This study demonstrates the value of the GVDN collaboration leveraging large population sizes to examine important vaccine safety questions regarding rare outcomes, as well as the value of linked population level datasets, such as VSHL, to rapidly explore associations that are identified.

Risk of encephalitis and meningitis after COVID-19 vaccination in South Korea: a self-controlled case series analysis

BACKGROUND

Several neurological manifestations shortly after a receipt of coronavirus infectious disease 2019 (COVID-19) vaccine have been described in the recent case reports. Among those, we sought to evaluate the risk of encephalitis and meningitis after COVID-19 vaccination in the entire South Korean population.

METHODS

We conducted self-controlled case series (SCCS) analysis using the COVID-19 immunization record data from the Korea Disease Control Agency between February 2021 and March 2022, linked with the National Health Insurance Database between January 2021 and October 2022. We retrieved all medical claims of adults aged 18 years or older who received at least one dose of COVID-19 vaccines (BNT162b2, mRNA-1273, ChAdOx1-S, or Ad26.COV2.S), and included only those who had a diagnosis record for encephalitis or meningitis within the 240-day post-vaccination period. With day 0 defined as the date of vaccination, risk window was defined as days 1-28 and the control window as the remainder period excluding the risk windows within the 240-day period. We used conditional Poisson regression to estimate the incidence rate ratios (IRR) with 95% confidence intervals (CI), stratified by dose and vaccine type.

RESULTS

From 129,956,027 COVID-19 vaccine doses administered to 44,564,345 individuals, there were 251 and 398 cases of encephalitis and meningitis during the risk window, corresponding to 1.9 and 3.1 cases per 1 million doses, respectively. Overall, there was an increased risk of encephalitis in the first 28 days of COVID-19 vaccination (IRR 1.26; 95% CI 1.08-1.47), which was only significant after a receipt of ChAdOx1-S (1.49; 1.03-2.15). For meningitis, no increased risk was observed after any dose of COVID-19 vaccine (IRR 1.03; 95% CI 0.91-1.16).

CONCLUSIONS

Our findings suggest an overall increased risk of encephalitis after COVID-19 vaccination. However, the absolute risk was small and should not impede COVID-19 vaccine confidence. No significant association was found between the risk of meningitis and COVID-19 vaccination.

What would have happened anyway? Population data source considerations when estimating background incident rates of adverse events following immunisation to inform vaccine safety

INTRODUCTION

Understanding background incident rates of adverse events following immunisation (AEFI) is essential to rapidly detect, evaluate, respond to, and communicate about vaccine safety concerns, especially for new vaccines. Creating estimates based on geographic specific population level data is increasingly important, as new AEFI presentations will be subject to the same local influences of population demography, exposures, health system variations and level of health care sought.

METHODS

We conducted a retrospective cohort analysis of hospital admissions, emergency department presentations and general practice consultations from 2015 to 2019-before introduction of COVID-19, Mpox or Shingrix vaccination-to estimate background incident rates for 37 conditions considered potential AEFI of special interest (AESI). Background incident rates per 100,000 population were calculated and presented as cases expected to occur coincidentally 1 day, 1 week and 6 weeks post-vaccination, by life-stage age-groups and presenting healthcare setting. We then assessed the proportional contribution of each data source to inform each AESI background rate estimate.

RESULTS

16,437,156 episodes of the 37 AESI were identified. Hospital admissions predominantly informed 19 (51%) of AESI, including exclusively ADEM and CVST; 8 AESI (22%) by primary care, and 10 (27%) a mix. Four AESI (allergic urticaria, Bell's palsy, erythema multiform and sudden death) were better informed by emergency presentations than admissions, but conversely 11 AESI (30%) were not captured in ICD-10 coded emergency presentations at all.

CONCLUSIONS

Emergent safety concerns are inevitable in population-wide implementation of new vaccines, therefore understanding local background rates aids both safety signal detection as well as maintaining public confidence in vaccination. Hospital and primary care data sources can be interrogated to inform expected background incident rates of adverse events that may occur following vaccination. However, it is necessary to understand which data-source provides best intelligence according to nature of condition and presenting healthcare setting.

The role of real-world evidence for regulatory and public health decision-making for Accelerated Vaccine Deployment- a meeting report

The COVID-19 pandemic underscored the need for rapid evidence generation to inform public health decisions beyond the limitations of conventional clinical trials. This report summarises presentations and discussions from a conference on the role of Real-World Evidence (RWE) in expediting vaccine deployment. Attended by regulatory bodies, public health entities, and industry experts, the gathering was a collaborative exchange of experiences and recommendations for leveraging RWE for vaccine deployment. RWE proved instrumental in refining decision-making processes to optimise dosing regimens, enhance guidance on target populations, and steer vaccination strategies against emerging variants. Participants felt that RWE was successfully integrated into lifecycle management, encompassing boosters and safety considerations. However, challenges emerged, prompting a call for improvements in data quality, standardisation, and availability, acknowledging the variability and potential inaccuracies in data across diverse healthcare systems. Regulatory transparency should also be prioritised to foster public trust, and improved collaborations with governments are needed to streamline data collection and navigate data privacy regulations. Moreover, building and sustaining resources, expertise, and infrastructure in LMICs emerged as imperative for RWE-generating capabilities. Continued stakeholder collaboration and securing adequate funding emerged as vital pillars for advancing the use of RWE in shaping responsive and effective public health strategies.

Incidence and Nature of Short-Term Adverse Events following COVID-19 Second Boosters: Insights from Taiwan's Universal Vaccination Strategy

This study evaluates the incidence and characteristics of adverse events (AEs) following the second COVID-19 booster dose, leveraging Taiwan's distinctive approach of extending booster vaccinations to all citizens, unlike the targeted high-risk group strategies in other countries. Utilizing data from Taipei Veterans General Hospital's Vaccine Adverse Event Reporting System (VAERS) from 27 October 2022 to 19 January 2023, this research examines AEs in 441 out of 1711 booster recipients, considering factors like age, vaccine brands, and booster combinations. The findings revealed incidence rates (IRs) of 25.6% (95% CI: 21.1-30.8) after the first booster and 24.9% (95% CI: 20.5-30.0) after the second, mostly non-serious, with those having AEs post-first booster being five times more likely to report them again (incidence rate ratio, 5.02, p < 0.001). Significantly, switching from the mRNA1273 vaccine to another brand reduced AE risk by 18%. This study underscores that AEs are more repetitive than cumulative with additional booster doses, advocating for personalized vaccination strategies based on individual medical histories and previous vaccine reactions. These insights are valuable for healthcare providers in discussing potential AEs with patients, thereby improving vaccine compliance and public trust, and for policymakers in planning future booster vaccination strategies.