Experts are also calling BA.2 a "stealth omicron," as there's a key difference in its genetic sequence that makes it harder to track.
Some doctors argue wearing masks outdoors should be mandated in certain situations, not just recommended.
Gov. Kate Brown's order -- which will take effect Friday -- is generally for everyone ages 5 and up, regardless of vaccination status.
The study is in line with others from around the world showing delta's increased tendency to cause largely minor infections among fully vaccinated people.
The CDC is urging expecting moms to get the COVID vaccine as hospitals are seeing disturbing numbers of unvaccinated pregnant women seriously ill.
One of the largest not-for-profit health systems in southeast Texas was forced to close three of its emergency rooms in the Houston area "due to the continued COVID-19 surge."
