AstraZeneca says that its COVID-19 vaccine is strongly effective even after counting additional illnesses in its U.S. study. The announcement late Wednesday was the latest in an extraordinary public dispute with American officials. The drugmaker said it had analyzed more data from that study and concluded the vaccine is 76% effective in preventing symptomatic COVID-19, instead of the 79% it had reported earlier in the week. Just a day earlier, an independent panel that oversees the study had accused AstraZeneca of cherry-picking data to tout the protection offered by its vaccine. The panel said the company had left out some COVID-19 cases that occurred in the study, a move that could erode trust in the science.