The study investigates the similarities and differences between disinformation campaigns related to the COVID-19 pandemic and the Russia-Ukraine war in Europe. The researchers highlight the hybrid nature of the current media system, with social networks playing a central role in the spread of disinformation. They define key terms such as disinformation, misinformation, hoax, propaganda, and post-truth, differentiating them based on intent and purpose. The COVID-19 pandemic is presented as an unprecedented event that exacerbated the spread of disinformation due to initial uncertainty and the exploitation of information voids by various actors, including anti-vaccine campaigners and populist political parties. The increased use of digital platforms during lockdowns amplified the impact of disinformation. The Russia-Ukraine war is framed as another significant event, marked by the unprecedented use of technology and social media in warfare, dubbed 'the first digital world war'. This war built upon Russia's earlier propaganda operations, leveraging social media channels to influence public opinion and polarize audiences. The role of fact-checkers in combating disinformation during both crises is emphasized, highlighting the need for a comparative analysis to understand common patterns and strategies.

The paper draws upon existing literature on information disorders, defining and differentiating concepts like disinformation, misinformation, hoaxes, propaganda, and post-truth. It cites research on the impact of the COVID-19 pandemic on the media system and the spread of disinformation through social media platforms. Furthermore, it reviews studies on the role of social media in the Russia-Ukraine war and the use of disinformation as a tool of hybrid warfare. The authors reference Hallin and Mancini's media model (2004) to contextualize their choice of countries (Spain, Germany, UK, and Poland) for analysis, highlighting the different media systems present in each region. Previous research on fact-checking methodologies and the use of fact-checking publications as data sources is also reviewed.

The research employed a mixed-methods approach, combining quantitative and qualitative techniques. The quantitative component involved a content analysis of 812 fact-checks from eight fact-checking organizations in four European countries (Spain, Germany, the UK, and Poland) over the period of March 2020-March 2023. The fact-checks were analyzed across five variables: frequency of fact-checking, format of hoaxes, hoax typology, hoax platform, and purpose of the hoax. The qualitative component consisted of eight semi-structured interviews with experts in fact-checking, disinformation on digital platforms, and European disinformation regulation. These interviews provided contextual insights and interpretations of the quantitative findings. The researchers used a 'most similar systems design' (MSSD) to compare disinformation patterns across the two events and four countries. The data were coded using a pre-defined coding manual, with a high level of inter-coder reliability achieved (92%). March was chosen for analysis as it marked significant moments in both the pandemic and the war.

The study revealed several key findings: 1. **Frequency of Hoaxes:** The highest frequency of verified hoaxes occurred in March 2020 (pandemic) and March 2022 (war), with a subsequent decline in both cases. The decline was steeper for the war, possibly due to reduced public attention. Spain had the highest number of verified hoaxes, due to both its role as a hub for disinformation and the strength of its fact-checking organizations. 2. **Format of Hoaxes:** Textual content was the predominant format during the pandemic, while a combined format of text and images dominated during the war. This is attributed to the visual nature of the war and the language barrier. The use of images bypassed language limitations, allowing for faster global dissemination. 3. **Typology of Hoaxes:** Fabricated content was the primary typology during the pandemic, whereas false context (out-of-context images) prevailed during the war. This finding highlights the different approaches to disinformation depending on the nature of the event. 4. **Platform of Hoaxes:** Social media, particularly Facebook and X (Twitter), were the dominant platforms for spreading hoaxes in both events, significantly surpassing traditional media and blogs. The study acknowledges the potential bias introduced by fact-checkers’ collaborations with these platforms. 5. **Purpose of Hoaxes:** The main purpose of hoaxes in both cases was to provoke emotional responses and to promote a common enemy, furthering polarization and division among audiences. The study highlights the transition of some disinformation groups from pandemic denialism to pro-Russia narratives during the war.

The findings demonstrate a clear link between the frequency of disinformation and the intensity of the events, with peaks coinciding with critical moments in the pandemic and the war. The shift in format and typology of disinformation reflects the distinct nature of each event, highlighting the adaptability of disinformation strategies. The almost exclusive reliance on social media underscores the critical role of these platforms in amplifying disinformation and the need for effective strategies to counter its spread. The prevalence of hoaxes aimed at provoking emotional responses and creating a common enemy reveals a calculated strategy to polarize audiences and undermine societal cohesion. The study confirms the hypothesis that disinformation campaigns adapt their methods based on the context of the crisis. The findings suggest that the spread of disinformation is not solely dependent on the volume of false content but also on audience engagement and the capacity of fact-checkers to address it. The study's findings contribute to our understanding of the evolution of disinformation campaigns and their impact on public discourse during major crises.

This research provides valuable insights into the characteristics and patterns of disinformation surrounding the COVID-19 pandemic and the Russia-Ukraine war in Europe. The study confirms that the frequency of disinformation is closely tied to the intensity of current events, with a decline observed after the initial peak. The shift from textual hoaxes during the pandemic to visually-driven disinformation during the war underscores the adaptability of disinformation strategies. The dominance of social media as a platform for spreading hoaxes highlights the need for effective countermeasures. Future research could explore the role of artificial intelligence in generating disinformation, examine the long-term effects of disinformation on public trust and political polarization, and develop more effective strategies to counter disinformation across different media platforms and cultural contexts.

The study's reliance on fact-checking publications introduces a potential bias, as fact-checkers might prioritize debunking hoaxes appearing on platforms they collaborate with. The temporal scope, focusing on March of each year, might not fully capture the fluctuations of disinformation throughout the entire period. A broader geographical scope and more extensive timeframe would enhance the study's generalizability. The interview sample, although expert-driven, represents a limited perspective, and the anonymization of interviews restricts the potential for further analysis of specific contributions.