Assessing the acceptability and feasibility of financial incentives to increase cervical cancer screening among women in vulnerable situations in Italy: a formative research protocol - Cristina Lumia; Francesca Squillace; Francesca De Nard; Francesca Marchetti; Davide Ausili; Simona Fumagalli; Antonella Nespoli; Alexandre Dumont (Archives of Public Health, 2026)