Cases of the COVID-19 delta variant continue to surge at a pace that would put some California counties back into the purple tier in the state's now-expired blueprint for reopening.
As expected, the delta variant is now the dominant strain in the U.S., making up 83% of the nation's current cases, a big jump from 50% the week of July 3.
In California, nearly half of all new COVID-19 cases are of the delta variant. For that reason, 17 California counties are now recommending that even fully vaccinated people wear masks when indoors. All Bay Area counties, except Solano County, are among those.
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Los Angeles County is the lone California county mandating a return to masks indoors.
Health officials across the region and the nation continue to urge people to get vaccinated, as all the authorized vaccines provide protection against the delta variant and because most of the new COVID-19 infections are people who are not vaccinated.
A new yet-to-be-published study out of New York University, however, suggests the single-shot Johnson & Johnson vaccine may be less effective against variants than the other two-dose COVID-19 vaccines from Pfizer and Moderna. Researchers analyzed blood samples from people who received one of the three vaccines and found the J&J shot was not as effective against the delta and lambda variants.
The study, which suggests those who received the J&J shot may need a booster shot, has not yet been peer reviewed nor published in a medical journal.