Breakthrough COVID-19 infections and deaths rose during delta, but far outpaced by the unvaccinated

As Americans brace for the possibility of another difficult winter ahead in the nation’s fight against coronavirus, there is a renewed sense of urgency to get as many people inoculated and boosted as quickly as possible, given the emergence of the highly contagious omicron variant -- now dominant in the U.S.

An ABC News analysis of federal and state data found that since July, there has been an acceleration of the number of breakthrough coronavirus cases, thus, of individuals who test positive after being fully vaccinated.

While federal data from the...