In this paper, we analyze excess mortality in Israel during the COVID-19 crisis, focusing on the age group of young adults under 50 years of age, as their susceptibility to COVID-19 mortality is low. Based primarily on online data from the Central Bureau of Statistics of Israel, we observed an unexpected rise of excess mortality among 20 to 49-year-olds in February-March 2021. It should be noted that excess mortality peaks among these young age groups are rarely observed, with low number of deaths that are usually caused by wars. We examined whether COVID-19 could account for this excess mortality. The inconsistency between the reported COVID-19 deaths and the excess deaths within this age group led to consider other potential causes: accident and vaccination. Indeed, the surge in mortality coincided with the rollout of the Israeli vaccination campaign for the 20 sto 49-year-olds, which reached more than 75% of individuals in this age group. This unexpected rise in excess mortality among young adults was also found in two other countries, the United Kingdom and Hungary, which have in common with Israel a massive vaccination of their populations. Thus, our observations should prompt to pause the campaign, while clarifying the underlying reasons for those excess deaths, especially in the context of a low mortality risk from COVID-19 within adults under 50 years of age.