The recent COVID-19 pandemic has triggered an enormous stream of information. Parascientific digital communication has pursued different avenues, from mainstream media news to social networking, at times combined. Likewise, citizens have developed new discourse practices, with readers as active participants who claim authority. Based on a corpus of 500 reader comments from The Guardian, we analyse how readers build their authorial voice on COVID-19 news as well as their agentive power and its implications. Methodologically, we draw upon stance markers, depersonalisation strategies, and heteroglossic markers, from the perspective of discursive interpersonality. Our findings unearth that stance markers are central for readers to build authority and produce content. Depersonalised and heteroglossic markers are also resorted, reinforcing readers' authority with external information that mirrors expert scientific communication. Conclusions suggest a strong citizen agentive power that can either support news articles, spreading parascientific information, or challenge them, therefore, contributing to produce pseudoscientific messages.