What we know about the new strain of the Delta variant, Delta-plus

Health experts are watching a new strain of the Delta variant, called Delta-plus, that is driving up new coronavirus cases in the United Kingdom.

Scientists are still learning about the strain, but some of research points to a higher level of transmissibility.

"So far, only a handful of Delta-plus cases have been identified in Massachusetts and only about 130 in the whole United States, vanishingly small numbers that suggest it’s not a major threat," writes Globe reporter Kay Lazar.

"However, scientists say it’s crucial to remain vigilant, saying there’s evidence that the new strain, known officially as Delta AY.4.2, may be 15 percent more transmissible than its parent, the Delta variant."