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This study asked whether the concurrent reinforcement of behavioral variability facilitates learning to emit a difficult target response. Sixty students repeatedly pressed sequences of keys, with an originally infrequently occurring target sequence consistently being followed by positive feedback. Three conditions differed in the feedback given to non-target sequences: concurrent positive feedback presented contingent on response variability, positive feedback presented non-contingently, or no reinforcement for any non-target responses (control condition). Contrary to the result of analogous rat studies, if anything, the participants in the control condition more readily learned to emit the target sequence than did the subjects in each of the other two conditions. It is argued that these contradictory findings are primarily caused by procedural differences, such as differences in the density of the reinforcement schedule applied to non-target behavior, rather than reflecting a true species difference.

Purpose: The European Medicines Agency (EMA) issued regulatory actions and communications in 2021 on thrombosis with thrombocytopenia syndrome (TTS) associated with adenovirus vector vaccines Vaxzevria or Jcovden. This study aimed to evaluate the impact of these actions on awareness, knowledge and implementation in practises of healthcare professionals (HCP)., Methods: Web-based cross-sectional surveys were conducted on HCPs engaged in the vaccination, monitoring or counselling about the vaccines. We measured awareness and knowledge of the risk of TTS and their implementation of recommendations in practise. Descriptive and qualitative analyses were conducted. This study took place in Greece, Latvia, Netherlands, Portugal and Slovenia., Results: We surveyed 1659 HCPs. From these, 914 were included in the analysis. Most were aware about the reports of TTS associated with COVID-19 adenovirus vector vaccines, with 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 impacted on professional practise of 55%-77% of HCPs. The reported use of product information across countries was moderate, with some variations., Conclusions: Awareness about and knowledge of TTS risk from COVID-19 adenoviral vector vaccines were high among HCPs. HCPs reported a clear preference for national guidelines as source of risk information and the implementation of product information remained moderate across countries., (© 2024 The Author(s). Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.)

Objective: In 2021, thrombosis with thrombocytopenia syndrome (TTS) was confirmed by the European Medicines Agency (EMA) as a rare side effect of the COVID-19 adenovirus vector vaccines Vaxzevria® and Jcovden®. This study aimed to describe the public's knowledge of TTS and how it affected the willingness to be vaccinated with COVID-19 vaccines and other vaccines in six European countries., Methods: From June to October of 2022, a multi-country cross-sectional online survey was conducted in Denmark, Greece, Latvia, Netherlands, Portugal, and Slovenia. The minimum target of participants to be recruited was based on the size of the country's population. The results were analysed descriptively., Results: In total, 3794 respondents were included in the analysis; across the six countries, 33.3 %-68.3 % reported being familiar with signs and symptoms of TTS, although 3.1-61.4 % of those were able to identify the symptoms correctly. The reported changes in willingness to be vaccinated against COVID-19 and with other vaccines varied per country. The largest reported change in the willingness to be vaccinated with Vaxzevria® and Jcovden® was observed in Denmark (61.2 %), while the willingness to be vaccinated with other COVID-19 vaccines changed most in Slovenia (30.4 %). The smallest decrease in willingness towards future vaccination against COVID-19 was reported in the Netherlands (20.9 %) contrasting with the largest decrease observed in Latvia (69.1 %)., Conclusion: Knowledge about TTS seemed to have influenced the public's opinion in Europe resulting in less willingness to be vaccinated with Vaxzevria® and Jcovden®. Willingness for vaccination against COVID-19 with other vaccines and widespread use of vaccines to prevent other diseases also differed and seemed to be determined by the approaches taken by national health authorities when reacting to and communicating about COVID-19 vaccination risks. Further investigation of optimal risk communication strategies is warranted., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Teresa Leonardo Alves reports financial support was provided by European Medicines Agency., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)