A summary of the Advisory Committee for Immunization Practices (ACIP) use of a benefit-risk assessment framework during the first year of COVID-19 vaccine administration in the United States

Utilising the Benefit Risk Assessment of Vaccines (BRAVE) toolkit to evaluate the benefits and risks of Vaxzevria in the EU: a population-based study

BACKGROUND

Several COVID-19 vaccines have been licensed. To support the assessment of safety signals, we developed a toolkit to support COVID-19 vaccine monitoring and benefit-risk assessment. We aim to show the application of our toolkit in the EU using thrombosis with thrombocytopenia syndrome (TTS) associated with the Vaxzevria (AstraZeneca) vaccine as a use case.

METHODS

In this population-based study, we used a model incorporating data from multiple EU sources such as The European Surveillance System and EudraVigilance, and estimated the benefits of COVID-19 vaccines by comparing the observed COVID-19 confirmed cases, hospitalisations, intensive care unit (ICU) admissions, and deaths across Europe to the expected numbers in the absence of Vaxzevria vaccination. Risks of TTS associated with Vaxzevria were calculated by comparing the observed number of TTS events in individuals who received Vaxzevria to the expected number of events based on background incidence rates. To visualise the results, we developed a toolkit with an interactive web application.

FINDINGS

62 598 505 Vaxzevria vaccines (32 763 183 to females and 29 835 322 to males) had been administered in Europe by Feb 10, 2021. Our results showed that a first dose of Vaxzevria provided benefits across all age groups. Based on vaccine effectiveness estimates and reported coverage in Europe, from Dec 13, 2020 to Dec 31, 2021, vaccination with Vaxzevria was estimated to prevent (per 100 000 doses) 12 113 COVID-19 cases, 1140 hospitalisations, 184 ICU admissions, and 261 deaths. Women aged 30-59 years and males aged 20-29 years had the highest frequency of TTS events. The benefits of vaccination outweighed the risks of TTS in all age groups, with the highest benefits and risks observed in individuals aged 60-69 years.

INTERPRETATION

Our toolkit and underlying model contextualised the risk of TTS associated with Vaxzevria relative to its benefits. The methodology employed could be applied to other serious adverse events related to COVID-19 or other vaccines. The adaptability and versatility of such toolkits might contribute to strengthening preparedness for future public health emergencies.

FUNDING

European Medicines Agency.

Estimating COVID-19 associated hospitalizations, ICU admissions, and in-hospital deaths averted in the United States by 2023-2024 COVID-19 vaccination: A conditional probability, causal inference, and multiplier-based approach

COVID-19-associated hospitalizations, ICU admissions, and in-hospital deaths averted from 2023 to 2024 COVID-19 vaccination from the weeks of October 1, 2023, through April 21, 2024, were estimated via a novel multiplier model that utilized causal inference, conditional probabilities of hospitalization, and correlations between data elements in Monte Carlo simulations. Median COVID-19-associated hospitalizations averted were 68,315 (95 % uncertainty interval [UI] 42,831-97,984), ICU admissions averted were 13,108 (95 % UI 4459-25,042), and in-hospital deaths averted were 5301 (95 % UI 101-14,230). Averted COVID-19-associated burden was highest in adults aged 65 years and older (hospitalizations averted 57,665, 95 % UI 35,442-84,006; ICU admissions averted 10,878, 95 % UI 3104-21,591; in-hospital deaths averted 4779, 95 % UI 0-13,132). Expanding the analytic period to comprise the weeks of September 24, 2023, through August 11, 2024, resulted in 107,197 COVID-19-associated hospitalizations averted (95 % UI 80,692-137,643), 18,292 COVID-19-associated ICU admissions averted (95 % UI 10,062-28,436), and 6749 COVID-19-associated in-hospital deaths averted (95 % UI 2077-13,557). Older adults had the highest COVID-19-associated averted burden and potential to reduce burden further through increased vaccine coverage. 2023-2024 COVID-19 vaccinations reduced the burden of COVID-19-associated severe disease.

Communicating on Vaccine Benefit-Risk Ratios: A Discrete-Choice Experiment among Health Care Professionals and the General Population in France

BACKGROUND

We explored preferences around the benefit-risk ratio (BRR) of vaccination among the general adult population and health care sector workers (HCSWs). We estimated preference weights and expected vaccine uptake for different BRR levels for a vaccine recommended during an infectious disease emergence. In addition, we explored how far qualitative information about disease severity, epidemiological context, and indirect protection interacts with these preferences.

METHODOLOGY

This was a cross-sectional study, using a self-administered online questionnaire containing a single-profile discrete choice experiment among HCSWs and the general population in France (quasi-representative sample). The questionnaire was available from January 12 to April 27, 2023, for HCSWs and from April 17 to May 3, 2023, for the general population. BRR is represented as the number of vaccine-prevented disease events for 1 event related to a vaccine side effect. Results are reported in 4 groups: general population sample, non-HCSWs, non-university-degree HCSWs, and university-degree HCSWs.

RESULTS

Among the 1,869 participants, 1,038 (55.5%) varied their vaccine decision among the different vaccine scenarios. Hypothetical vaccine acceptance among university-degree HCSWs increased when the vaccination BRR was 100:1, while non-university-degree HCSWs and non-HCSWs were more sensitive to qualitative information about the vaccine BRR than quantitative indicators. Among participants in the general population sample with varied decisions, expected acceptance increased by 40% sample if disease risk was high. Among serial vaccine nondemanders, high disease risk decreased their certitude to refuse hypothetical vaccination.

CONCLUSION

Our results suggest that only university-degree HCSWs are sensitive to the notion of BRR, but not the general public. Given that previous research found speaking about BRR might reduce vaccine acceptance, this notion should be avoided in vaccine promotion.

HIGHLIGHTS

The notion of benefit-risk ratio (BRR) of vaccination appears to be taken into account in vaccine decisions by university-degree HCSWs, but not by the general public. Mentioning a favorable BRR could imply that the vaccine is not safe and reduce vaccine motivation.Mentioning qualitative attributes of BRR surrounding disease frequency and severity, and indirect protection effects, strongly affected theoretical vaccine decisions in all participants, irrespective of professional categories.Expected vaccine acceptance increased by 40% among the general population sample if disease risk was presented as high, and expected vaccine coverage exceeded 50% in scenarios with high disease risk.Among those refusing vaccination in all vaccine scenarios, only a high risk of developing the disease decreased their certitude to refuse vaccination. This further underlines the importance of disease risk perception on vaccine decision making, including among persons who a priori are unlikely to accept vaccination.

Direct quantitative comparison of benefits and risks of COVID-19 vaccines used in National Immunization Technical Advisory Groups Guidance during the first two years of the pandemic

INTRODUCTION

The balance of benefits and harms of vaccines are assessed by regulatory agencies and National Immunization Technical Advisory Groups (NITAGs) to inform vaccine authorization or guidance. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach has been adopted by many NITAGs to develop recommendations. During the COVID-19 pandemic, several NITAGs additionally used direct quantitative comparisons (DQCs) between benefits and risk of vaccination with or without a GRADE framework to support timely decision-making relating to emerging safety signals. This study aimed to document the role of DQCs as novel tools in NITAGs' work by identifying situations where DQCs have been clearly leveraged in NITAG guidance, as well as identifying their strengths and limitations.

METHODS

The MEDLINE database and NITAGs' websites listed in the Global NITAG Network were searched for NITAG publications on COVID-19 vaccines. Publications were included if a DQC between benefits and risks of any COVID-19 vaccine was explicitly used for NITAG decision-making. Two reviewers independently assessed publication eligibility and extracted data. A narrative description of the role of DQCs in NITAG guidance, DQCs' methods and limitations was conducted.

RESULTS

Overall, 23 publications with 18 DQCs used by seven NITAGs were included. Situations prompting these publications included new safety signals (n = 7), additional information available on previously identified safety signals (n = 4) and changing contexts (n = 15) (e.g., vaccine supply, and epidemiology). DQC simplicity made them accessible, timely, and allowed for transparent communication. DQCs heavily relied on assumptions making them sensitive to changes in model parameters. DQCs limitations made them not easily transferable to other contexts and they quickly became obsolete in the evolving context of the COVID-19 pandemic.

CONCLUSIONS

The use of DQCs by NITAGs during the COVID-19 pandemic allowed for rapid evidence-based decision-making in an evolving environment while maintaining public trust. However, if their use becomes standard practice, efforts should be made to address their limitations.

The WHO Algorithm for Causality Assessment of Adverse Effects Following Immunization with Genetic-Based Anti-COVID-19 Vaccines: Pitfalls and Suggestions for Improvement

Clarifying and differentiating the causes of diseases is an essential step in any clinical activity, but it takes on particular relevance and complexity in the case that arise following vaccinations. The WHO has proposed a protocol that uses a list of specific questions about vaccine-related adverse events and an algorithm for making a judgement. Here, we analyze and discuss the important limitations of this protocol when applied to the new genetic-based anti-COVID-19 vaccines, particularly once dealing with rare and unexpected pathological events. The main controversial aspects concern: (a) the prevailing consideration of other possible causes; (b) the biological plausibility and the choice of an appropriate time window to consider adverse effects possibly caused by vaccines; (c) the reference to scientific literature, which may be very limited and often controversial in early stages of introducing new vaccines because of the short period of observation; (d) the final classification of the algorithm into only three classes, which leaves ample space for the "indeterminate" category. Failure to address these issues may lead to distorted pharmacovigilance reports with significant consequences on the benefit/harm assessment. In anticipation of possible future pandemics managed with new vaccines, the WHO algorithm needs to be revised with appropriate protocols for monitoring and evaluation of adverse effects that take into account the novel mechanism of action and real-world epidemiological data.

Development of COVID-19 vaccine policy - United States, 2020-2023

COVID-19 vaccines represent a great scientific and public health achievement in the face of overwhelming pressures from a global pandemic, preventing millions of hospitalizations and deaths due to COVID-19 vaccines in the United States. Over 675 million doses of COVID-19 vaccines have been administered in the United States, and over 80% of the U.S. population has had at least 1 dose of a COVID-19 vaccine. Over the course of the COVID-19 pandemic in the United States, over one million people died from COVID-19, and over six million were hospitalized. It has been estimated that COVID-19 vaccines prevented more than 18 million additional hospitalizations and more than 3 million additional deaths due to COVID-19 in the United States. From the beginning of the COVID-19 pandemic in 2020 through June 2023, ACIP had 35 COVID-19 focused meetings and 24 votes for COVID-19 vaccine recommendations. ACIP had the critical task of rapidly and thoroughly reviewing emerging and evolving data on COVID-19 epidemiology and vaccines, as well as making comprehensive population-based recommendations for vaccine policy and considerations for implementation through a transparent and evidence-based framework. Safe and effective COVID-19 vaccines, recommended through transparent policy discussions with ACIP, remain the best tool we have to prevent serious illness, hospitalization and death from COVID-19.

Comparative safety of monovalent and bivalent mRNA COVID-19 booster vaccines in adolescents aged 12 to 17 years in the Republic of Korea

BACKGROUND

This study analyzed the safety of coronavirus disease 2019 (COVID-19) bivalent and monovalent booster vaccines, including the frequency of adverse events (AEs) such as myocarditis and pericarditis, in adolescents aged 12 to 17 years in the Republic of Korea. We aimed to share the safety profile of the COVID-19 bivalent vaccine booster doses.

METHODS

We analyzed the frequencies of AEs reported to the COVID-19 vaccination management system (CVMS) or self-reported through the text message survey (TMS). Diagnostic eligibility and causality with vaccines were compared using odds ratios (ORs) by vaccine type, and incidence rates per 100,000 person-days were calculated for confirmed cases of myocarditis and pericarditis following monovalent and bivalent booster doses.

RESULTS

In the CVMS, the AE reporting rate (per 100,000 doses) was lower after the bivalent booster (66.5) than after the monovalent booster (264.6). Among the AEs reported for both monovalent and bivalent vaccines 98.3% were non-serious and 1.7% were serious. According to the TMS, both local and systemic AEs were reported less frequently after the bivalent vaccination than after the monovalent vaccination in adolescents aged 12 to 17 years (p<0.001). The incidence rates per 100,000 person-days for confirmed myocarditis/pericarditis following monovalent and bivalent booster doses were 0.03 and 0.05, respectively; this difference was not statistically significant (OR, 1.797; 95% confidence interval, 0.210-15.386).

CONCLUSION

AEs in 12- to 17-year-olds following the bivalent booster were less frequent than those following the monovalent booster in the Republic of Korea, and no major safety issues were identified. However, the reporting rates for AEs were low.

mRNA Technology and Mucosal Immunization

Current mRNA vaccines are mainly administered via intramuscular injection, which induces good systemic immunity but limited mucosal immunity. Achieving mucosal immunity through mRNA vaccination could diminish pathogen replication at the entry site and reduce interhuman transmission. However, delivering mRNA vaccines to mucosae faces challenges like mRNA degradation, poor entry into cells, and reactogenicity. Encapsulating mRNA in extracellular vesicles may protect the mRNA and reduce reactogenicity, making mucosal mRNA vaccines possible. Plant-derived extracellular vesicles from edible fruits have been investigated as mRNA carriers. Studies in animals show that mRNA vehiculated in orange-derived extracellular vesicles can elicit both systemic and mucosal immune responses when administered by the oral, nasal, or intramuscular routes. Once lyophilized, these products show remarkable stability. The optimization of mRNA to improve translation efficiency, immunogenicity, reactogenicity, and stability can be obtained through adjustments of the 5'cap region, poly-A tail, codons selection, and the use of nucleoside analogues. Recent studies have also proposed self-amplifying RNA vaccines containing an RNA polymerase as well as circular mRNA constructs. Data from parenterally primed animals demonstrate the efficacy of nasal immunization with non-adjuvanted protein, and studies in humans indicate that the combination of a parenteral vaccine with the natural exposure of mucosae to the same antigen provides protection and reduces transmission. Hence, mucosal mRNA vaccination would be beneficial at least in organisms pre-treated with parenteral vaccines. This practice could have wide applications for the treatment of infectious diseases.