J&J Covid-19 Vaccine Was 66% Effective in Late-Stage Study

Johnson & Johnson said its experimental Covid-19 vaccine was 66% effective at protecting people from moderate to severe disease in a large clinical trial, positive results that could pave the way for its deployment across the U.S. within weeks.

The shot didn’t test as strongly as the two Covid-19 vaccines already in use in the U.S. Its effectiveness might have been impacted by new variants that the older shots didn’t test against, however, and it will still provide strong protection, health experts said.

Its arrival could also make a big difference in vaccination efforts hobbled by limited supplies, providing a new, large source of doses. And many health authorities might find it easier to administer the J&J vaccine, which is easier to store and…