We study how past exposure to the transatlantic and Indian ocean slave trade has an impact on present attitude towards public health interventions such as vaccination programs in Sub-Saharan Africa. We elaborate on avenues for investigating causal relationship between cultural norms of mistrust inherited by mothers from different ethnic group and their children vaccination decision. Especially, we provide evidence through a rich sample of Demographic Health Survey individual level data that ethnicity through its relationship with cultural trust is a salient causal channel. We find a negative and significant effect of slave trade on parent's likelihood to immunize their children against measles. We show that this negative effect goes both through direct vertical transmission of norms by parents and horizontal transmission from negative spillovers of living in low trustworthy environment. There is evidence that both effects are relatively important. We show that the results are not potentially driven by the size effect of the group or discrimination towards smaller ethnic minorities. As for the magnitude of the effect, we find that past exposure to slave trade has a negative impact nearly offsetting the benefit from membership in the highest 20% income quantile. Our calibration predicts an important decrease in measles incidence in the Hausa ethnic group form Northern Nigeria had they been a slave free group and thus inherited cooperative norms. Using different strategies, we argue that the observed linked is not picking-up the effect of pre-colonial ethnic group characteristics such as centralization or rigidity of social norms. Moreover, a falsification test with less trust sensitive disease such as malaria supports the argument that slave trade is impacting the vaccination decision through its effect on mistrust.