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What scientists do and don’t know about the Oxford–AstraZeneca COVID vaccine

Results confirming the vaccine’s strong protection against COVID-19 were welcomed following last week’s pause in roll-outs — but fresh questions have now emerged about the data.
  1. Smriti Mallapaty
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  2. Ewen Callaway
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The road keeps getting bumpier for a vaccine that most researchers say is safe and effective and has huge potential to protect large swathes of the world’s population. Less than a day after the University of Oxford and the pharmaceutical firm AstraZeneca reported positive early results from the largest trial so far of their COVID-19 vaccine, officials at a US government agency overseeing the trial questioned claims about the vaccine’s efficacy.

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Nature 592, 15-17 (2021)

doi: https://doi.org/10.1038/d41586-021-00785-7

Additional reporting by Heidi Ledford.

Updates & Corrections

  • Correction 25 March 2021: An earlier version of this story said Hilda Bastian was based in Gold Coast, Australia.

  • Update 25 March 2021: This story was updated to include AstraZeneca’s latest efficacy figure for the vaccine.

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