Social work during the COVID-19 crisis has faced one of the most challenging times to cover urgent social needs in an uncertain scenario. This study analyzes the immediate responses in social work to vulnerable groups in the first 15 days of the pandemic in Barcelona, one of the most affected areas worldwide by COVID-19. The sample for this qualitative study includes 23 semi-structured interviews with social workers from different fields of intervention, from general approaches (primary care) to specific ones (health, ageing, homeless, and justice). The data analysis followed the communicative methodology, including transformative and exclusionary dimensions, and the analytical categories focused on the impact of the COVID-19 pandemic on social services users, the organizational responses of social workers, and the impact of the interventions to cover urgent social needs of attendees. The interventions have been accompanied by an improvement in communication channels with vulnerable groups, ensuring an understanding of the situation of families and individuals, and covering the most urgent social needs. The study shows the key role of social workers from diverse social attention tools and their contribution to the sustainability of social services with a long-term impact.