18 breakthrough deaths were reported last week More than 4,000 fully vaccinated people in Massachusetts tested positive for the coronavirus last week, a daily average of more than 600 people as breakthrough infections continue to rise each week amid the delta variant. The rate of breakthrough infections week-over-week starting five weeks ago surged 64%, then the following week went up 20%, the next week jumped by 25%, the subsequent week increased by 20%, and in the last week climbed by 23%. Breakthrough cases in Massachusetts are making up about one-third of the state’s overall cases. People who are unvaccinated are...