US regulators have found the single-shot Johnson & Johnson coronavirus vaccine is safe and effective. It paves the way for it to become the third Covid-19 vaccine to be authorised in the US, possibly within days. The vaccine would be a cost-effective alternative to the Pfizer and Moderna vaccines, and can be stored in a refrigerator instead of a freezer. Trials found it prevented serious illness but was 66% effective overall when moderate cases were included. The company has agreed to provide the US with 100 million doses by the end of June. The UK, EU and Canada have also ordered doses and 500 million doses have also been ordered through the Covax scheme to supply poorer nations.(BBC)…[+]