(Reuters) - India on Friday became the fourth country to approve a coronavirus vaccine developed by Oxford University and AstraZeneca, authorising the vaccine’s rollout in coming weeks in the country with the second highest number of infections. The following is what we know about the race to deliver vaccines to help end the coronavirus pandemic, which has killed more than 1.8 million people worldwide: WHO IS FURTHEST ALONG? U.S. drugmaker Pfizer and German partner BioNTech have been the COVID-19 vaccine trailblazers. On Nov. 18, they became the first in the world to release full late-stage trial data. Britain was the first to approve the shot for emergency use on Dec. 3, followed by Canada on Dec. 9 and the U.S. Food and Drug Administration (FDA) on Dec. 11. Several other countries, including Saudi Arabia and Mexico, have also approved it. The European Medicines Agency (EMA) approved the shot on Dec. 21 and India is accelerating its review. The World Health Organization on Thursday listed the vaccine for emergency use, in a move seeking to speed access to it in the developing world. WHAT ABOUT MODERNA? Moderna Inc was a close second to Pfizer in many countries after it released a full data analysis for a late-stage trial on Nov. 30 showing a 94.1% efficacy rate for its vaccine. The United States authorised Moderna’s vaccine on Dec. 19, while Canada approved the shot on Dec. 23 and the European Medicines Agency (EMA) will do so on Jan. 6. ASTRAZENECA India approval of a two-dose version of AstraZeneca’s vaccine, COVISHIELD, which has also been given the green light by Britain, Argentina and El Salvador, is a major win for a shot seen as crucial for mass immunisations. Questions about the robustness of its trial data have complicated the approval process. The British company announced interim late-stage trial data in November showing two full doses were 62% effective while a half-dose followed by a full dose had a 90% success rate - but UK regulators the more successful outcome had not stood up to analysis. AstraZeneca is also in discussions with the European Union’s European Medicines Agency, which is conducting a rolling review of the vaccine. WHO ELSE IS IN THE RUNNING? U.S. drugmaker Johnson & Johnson plans to deliver trial data in January, teeing it up for U.S. authorisation in February if its shot is effective. It reduced the enrolment target for its clinical trial to 40,000 volunteers from 60,000 on Dec. 9, potentially speeding results that are tied to how quickly participants become infected. U.S. firm Novavax is running a late-stage trial in Britain with data due in the first quarter of 2021. It expects to start a large-scale trial in the United States this month. France’s Sanofi and Britain’s GlaxoSmithKline, however, announced a setback on Dec. 11 in their attempts to develop a vaccine. The drugmakers said that it showed an insufficient immune response in older people in mid-stage trials and that they would start a new study in February. WHAT HAPPENS IN THE TRIALS? The companies usually test their vaccines