Social media platform (SMP) use has intensified during the COVID-19 pandemic. New user groups are utilising SMPs more frequently to satisfy their unmet psychological needs. However, research to date has insufficiently explored variations in SMP use due to the pandemic. As the pandemic has adversely impacted the general public’s mental health, we propose and then apply the Temporal-Needs-Affordances-Features (T-NAF) model in this context. Public engagement with two international mental health awareness campaigns on Twitter were tracked over four years. Results show that the pandemic initially coincided with a significant increase in engagement (e.g., retweets) and a significant decrease in network size (e.g., followers). This establishes that a larger proportion of individuals engaged with resharing behaviour as the pandemic commenced, reinforcing the importance of SMPs in relation to mental health and needs satisfaction. This study also highlights the importance of temporality in social media research. Future research pathways are discussed.