WASHINGTON, United States (AFP) — British-Swedish drugmaker AstraZeneca on Wednesday revised down by three percentage points the effectiveness of its Covid vaccine after American authorities raised concerns that results reported from its US trial were outdated. The company now says its vaccine is 76 rather than 79 percent effective at preventing any kind of symptomatic Covid. It remains 100 percent effective against severe Covid, it added. The move came after an independent panel of experts […]