Background Recurrent measles outbreaks followed by mass vaccination campaigns (MVCs) occur in urban settings in sub-Saharan countries. An understanding of the reasons for this is needed to improve future vaccination strategies. The 2017 measles outbreak in Guinea provided an opportunity to qualitatively explore suboptimal vaccination coverage within an MVC among participants through their perceptions, experiences and challenges. Methods We conducted focus group discussions with caregivers (n=68) and key informant interviews (n=13) with health professionals and religious and community leaders in Conakry. Data were audio-recorded, transcribed verbatim from Susu and French, coded and thematically analysed. Results Vaccinations were widely regarded positively and their preventive benefits noted. Vaccine side effects and the subsequent cost of treatment were commonly reported concerns, with further knowledge requested. Community health workers (CHWs) play a pivotal role in MVCs. Caregivers suggested recruiting CHWs from local neighbourhoods and improving their attitude, knowledge and skills to provide information about vaccinations. Lack of trust in vaccines, CHWs and the healthcare system, particularly after the 2014–2016 Ebola epidemic, were also reported. Conclusions Improving caregivers’ knowledge of vaccines, potential side effects and their management are essential to increase MVC coverage in urban settings. Strengthening CHWs’ capacities and appropriate recruitment are key to improving trust through a community involvement approach.