Gov. Charlie Baker is optimistic that the Johnson & Johnson vaccine approved for emergency use over the weekend will accelerate the effort to get more Massachusetts residents protected against COVID-19, even if states will face a gradual ramp-up in delivery. While Massachusetts forges ahead to ease COVID-19 restrictions on businesses — despite warnings against doing so from federal health officials — Baker said Monday that he is hopeful J&J doses will "dramatically boost" the work to get shots in arms. Unlike the two-dose Pfizer and Moderna options already in public use, the Johnson & Johnson vaccine to which the U.S. Food and Drug Administration awarded emergency use authorization on Saturday requires just a single shot with simpler transportation and storage requirements.