AstraZeneca says that it will submit preliminary data from large clinical trials in the U.K. and Brazil to the FDA as part of an application for emergency authorization. Data from those trials show the vaccine was about 70 percent effective across two different dosing regimens. When the vaccine was given as a half dose and then a full dose one month later to about 2,700 participants, it had an efficacy of 90 percent. When given as two full doses at least one month apart to about 8,900 participants, it showed 62 percent efficacy. The company says it will work with the FDA to adjust the design of its late-stage U.S. trial to test the half-dose regimen, rather than the higher dose that proved less effective in the U.S and Brazil studies.