Utilising the Benefit Risk Assessment of Vaccines (BRAVE) toolkit to evaluate the benefits and risks of Vaxzevria in...

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.

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.

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.

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.

European Medicines Agency.