Impact of risk communication on thrombosis with thrombocytopenia syndrome for COVID-19 adenovirus vector vaccines on European healthcare professionals

Funding: The research leading to these results was conducted as part of the activities of the EU PE&PV (Pharmacoepidemiology and Pharmacovigilance) Research Network which is a public academic partnership coordinated by the Utrecht University, the Netherlands. The project has received support from the European Medicines Agency under the Framework service contract nr EMA/2018/23/PE. The content of this abstract expresses the opinion of the authors and may not be understood or quoted as being made on behalf of or reflecting the position of the European Medicines Agency or one of its committees or working parties.

Background: The European Medicines Agency (EMA) issued regulatory actions and communications in 2021 on thrombosis with thrombocytopenia syndrome (TTS) associated with adenovirus vector vaccines Vaxzevria and Jcovden.

Objective: To evaluate the impact of EMA regulatory actions on knowledge, attitudes, and practices of healthcare professionals (HCP).

Methods: Web-based cross-sectional surveys were conducted on HCPs who engaged in the vaccination, monitored or counselled about the vaccines. We measured awareness and knowledge of the risk of TTS and their adherence to recommendations contained in product information. This study was conducted in Greece, Latvia, Netherlands, Portugal and Slovenia.

Results: We surveyed 1659 HCPs. From these, 914 were included in the analysis. Most HCPs were aware about the reports of TTS associated with COVID-19 adenovirus vector vaccines, with all countries reporting percentages between 85 and 97%. Mainstream media, health authorities and peers were the main sources of TTS risk information. Most HCPs were able to identify key symptoms from TTS but were less familiar with minor symptoms. Guidelines from health authorities on COVID-19 vaccination have impacted the professional practice of half to two-thirds of HCPs. The reported use of product information across countries was moderate, with some variations.

Conclusion: Awareness about TTS risk of COVID-19 adenoviral vector vaccines was high among HCPs. HCPs reported a clear preference for national guidelines as source of risk information, with the actual use of product information remaining moderate across countries.