British / Swedish drugmaker AstraZeneca has announced promising results in developing a vaccine. An early analysis of some of its late-stage clinical trials, conducted in the UK and Brazil, showed that its coronavirus vaccine was 70.4 percent effective in preventing Covid-19, suggesting that the world could eventually have at least three working vaccines - and greater supply - to help curb the pandemic. However, doubts are being expressed about the results of the trials, mainly because they are based on a very small sample of people. British scientists are defending the validity of the findings, and look forward to further evidence becoming available in December. See