We address the diffusion of information about the COVID-19 with a massive
data analysis on Twitter, Instagram, YouTube, Reddit and Gab. We analyze
engagement and interest in the COVID-19 topic and provide a differential
assessment on the evolution of the discourse on a global scale for each
platform and their users. We fit information spreading with epidemic models
characterizing the basic reproduction numbers $R_0$ for each social media
platform. Moreover, we characterize information spreading from questionable
sources, finding different volumes of misinformation in each platform. However,
information from both reliable and questionable sources do not present
different spreading patterns. Finally, we provide platform-dependent numerical
estimates of rumors’ amplification.