A key research centre in the US – .css-yidnqd-InlineLink:link{color:#3F3F42;}.css-yidnqd-InlineLink:visited{color:#696969;}.css-yidnqd-InlineLink:link,.css-yidnqd-InlineLink:visited{font-weight:bolder;border-bottom:1px solid #BABABA;-webkit-text-decoration:none;text-decoration:none;}.css-yidnqd-InlineLink:link:hover,.css-yidnqd-InlineLink:visited:hover,.css-yidnqd-InlineLink:link:focus,.css-yidnqd-InlineLink:visited:focus{border-bottom-color:currentcolor;border-bottom-width:2px;color:#B80000;}@supports (text-underline-offset:0.25em){.css-yidnqd-InlineLink:link,.css-yidnqd-InlineLink:visited{border-bottom:none;-webkit-text-decoration:underline #BABABA;text-decoration:underline #BABABA;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-skip-ink:none;text-decoration-skip-ink:none;text-underline-offset:0.25em;}.css-yidnqd-InlineLink:link:hover,.css-yidnqd-InlineLink:visited:hover,.css-yidnqd-InlineLink:link:focus,.css-yidnqd-InlineLink:visited:focus{-webkit-text-decoration-color:currentcolor;text-decoration-color:currentcolor;-webkit-text-decoration-thickness:2px;text-decoration-thickness:2px;color:#B80000;}}Duke University in North Carolina – is trying to keep tabs on all the deals being done. It estimates that 6.4 billion doses of potential vaccines have already been bought, and another 3.2 billion are either under negotiation or reserved as “optional expansions of existing deals”.