Abstract Background The Netherlands experiences an unprecedented increase in meningococcal W infections. A national catch-up menACWY vaccination campaign started in October 2018, covering birth cohorts 2001-2005. To understand menACWY vaccination decisions, our study reports on perceptions of risks and their influence on menACWY vaccination intentions during an ongoing outbreak of meningococcal infections. Methods Online surveys were administered in September 2018 among adolescents (AD) targeted for menACWY vaccination (N = 3036) and parents (PA) of these adolescents (N = 3002). Following a mental models approach, survey items addressed knowledge and beliefs of meningococcal disease, the menACWY vaccination and vaccinations in general, and menACWY vaccination intention. Random Forest Analyses were conducted to identify those knowledge and beliefs that strongest predict vaccination intention. Results The response was 52.8% (N = 1603) in AD and 57.1% (N = 1784) in PA. 71% Of AD and 83% of PA indicated a positive vaccination intention. Most respondents perceived meningococcal disease as a severe disease with possible deathly consequences and were aware of transmission routes. Some misbeliefs of vaccines were rather strongly represented, with respectively 35% of AD and 45% of PA thinking that each year a number of children dies due to vaccination side effects. Preliminary results indicate that perceptions of vaccines in general, especially concerning the need for and the effectiveness, were the strongest predictors of vaccination intention in both AD and PA. Conclusions Adolescents and their parents seemed well informed about meningococcal disease, but less about vaccinations. The belief that vaccines are needed and effective in preventing infectious diseases seems to be of more importance in vaccination decisions than other beliefs of disease and vaccination. Future communications need to address the identified misbeliefs and emphasize the need for and effectiveness of vaccines. Key messages MenACWY vaccination ...