AstraZeneca issued a revised efficacy rate for its Covid-19 vaccine late Wednesday after a U.S. health agency questioned the accuracy of a preliminary report published earlier this week. The company said its vaccine is 76% effective in protecting against symptomatic cases of Covid, down from the 79% symptomatic efficacy rate it reported on Monday.
Here are some of the biggest developments Thursday:

The U.S. is recording at least 57,500 new Covid-19 cases and at least 970 virus-related deaths each day, based on a seven-day average calculated by CNBC using Johns Hopkins University data as of 7 a.m. ET.
The following data was compiled by Johns Hopkins University:
- Global cases: More than 125.23 million
- Global deaths: At least 2.74 million
- U.S. cases: More than 30.05 million
- U.S. deaths: At least 545,941