evidence: This tweet published on 4 July 2021 claimed that 99.2% of the COVID-19 deaths in June 2021 in the U.S. occurred among unvaccinated people, implying that vaccination might prevent most COVID-19 deaths. The tweet was later shared on Facebook by the political commentator Brian Tyler Cohen, receiving thousands of interactions in one day. [...] Due to these and other data limitations, the CDC doesn’t officially estimate the percentage of COVID-19 cases, hospitalizations, and deaths occurring in fully vaccinated people. Still, the director of the U.S. CDC, Rochelle Walensky, said at a 1 July 2021 White House briefing that preliminary data from January to June 2021 suggested that about 99.5% of COVID-19 deaths in the U.S. occurred in unvaccinated people. [...] In summary, the claim that most COVID-19 deaths occurred among unvaccinated individuals is accurate, according to available evidence. No vaccine is 100% effective, and therefore a small number of hospitalizations and deaths are expected among fully vaccinated individuals. However, recent data from the U.S. and other countries suggest that COVID-19 vaccines are highly effective and might prevent most COVID-19 severe cases and deaths in the U.S.