Before revision:  however, we found a large increase in the proportion of state-sponsored propaganda among non-credible and less credible URLs, suggesting that COVID-19 may be used as a vector to spread misinformation and disinformation for political purposes. Overall, results indicate that COVID-19 is unfolding in a highly uncertain information environment that not may amenable to fact-checking as scientific understanding of the disease, and appropriate public health measures, evolve. As a consequence, public service announcements must adequately communicate the uncertainly underlying these recommendations, while still encouraging healthy behaviors .
After revision:  however, we found a large increase in the proportion of state-sponsored propaganda outlets on Twitter. Finally, a known conspiracy theory was more likely to be ``laundered'' through social media platforms than low-credibility news sources. In contrast, misinformation reflecting legitimate scientific uncertainty was primarily discussed by credible news sources. These results suggest that the social media discourse reflects an attempt to come to grips with deep scientific uncertainty during an emerging pandemic, with significant content emanating from unrated; not low credibility, sources. When low-quality content is generated by these unrated sources, they may be amplified by high-credibility sources inadvertently lending them credibility .