AstraZeneca manufacturing error clouds vaccine study results

FILE - In this undated file photo issued by the University of Oxford on Monday, Nov. 23, 2020, a researcher in a laboratory at the Jenner Institute in Oxford, England, works on the coronavirus vaccine developed by AstraZeneca and Oxford University. With major COVID-19 vaccines showing high levels of protection, British officials are cautiously — and they stress cautiously — optimistic that life may start returning to normal by early April. Even before regulators have approved a single vaccine, the U.K. and countries across Europe are moving quickly to organize the distribution and delivery systems needed to inoculate millions of citizens. (University of Oxford/John Cairns via AP, File)