"...this study can help policymakers to more efficiently target relevant groups to limit the spread of misinformation."

The spread of fake news has often been attributed to the rise of social media platforms that allow for the rapid dissemination of false or misleading information to a broad audience. The rise in social media usage is particularly pronounced in low- and middle-income countries (LMICs), where the majority of the world's population lives. The research reported in this paper involved online surveys conducted in six sub-Saharan African countries (Ghana, Kenya, Nigeria, South Africa, Tanzania, Uganda) to analyse the individual-level determinants of spreading fake news. More specifically, it examines (deliberate and accidental) actual sharing behaviour of vaccine-related fake news - unsubstantiated infertility claims of vaccines for polio, human papillomavirus (HPV), and COVID-19 - on Facebook.

As part of the surveys, participants read one fake news article ("...It seems the new 'nOPV2' polio vaccine is yet another attempt of Western medicine to reduce Africa's population. Make sure that everyone is aware of the side-effects of the 'nOPV2' polio vaccine!"), were asked about their willingness to share it on Facebook, and were ultimately able to share the article. The surveys were conducted in early 2023 and gathered information from 5,307 participants. The study framework relates the actual sharing of fake news to several socioeconomic characteristics (age, gender, employment status, education), social media consumption, personality factors, and vaccine-related characteristics while controlling for country and vaccine-specific effects.

In this sample:

• 54.7% of respondents correctly detected that the article contained misinformation. In particular: Women, respondents with better cognitive skills, and persons with lower levels of institutional trust were more likely to detect misinformation.
• 52.1% of respondents stated they would be willing to share the article on their Facebook account. About 40% of respondents with this intention can be classified as deliberate and about 60% as accidental distributors of misinformation. In particular: Respondents who are older, male, richer, and risk-loving and those with higher levels of institutional trust and lower cognitive skills were more willing to share the fake news article.
• 13.8% of respondents actually shared the article on Facebook. Thus, substantially fewer people actually share fake news articles compared to those who stated their intention to do so. About 37% who shared did so deliberately; about 63% did so accidentally. Relative to the results of studies in the United States that observed actual sharing behaviour (in the political context), actual sharing rates in the present study are substantially higher.
• While deliberate sharing is related to being older and risk-loving, accidental sharing is associated with being older, male, and high levels of trust in institutions.
• The determinants of sharing differ by the adopted measure (intentions vs. actual sharing), which underscores the limitations of commonly used intention-based measures to derive insights about actual fake news sharing behaviour.

Thus, this study confirms the importance of age in spreading misinformation. The results show that while older persons are more likely to detect misinformation, they are still more likely to share misinformation both accidentally and deliberately. A further insight concerns the relationship between trust and accidental sharing, hinting towards the use of the information source as a credibility signal in the decision to share the article. Such heuristics help social media users rapidly make decisions but may trick them into sharing misinformation, particularly when misinformation is provided by seemingly trustworthy sources. Official sources should pay particular attention to distributing valid and truthful information.

In conclusion, this study sheds light "on the detection and sharing of health misinformation in a realistic online setting, providing novel insights on who is susceptible to fall for and more likely to disseminate fake news."