On Apr. 22, 2021, the Strategic Advisory Group of Experts (SAGE) on Immunization annouced updated interim guidance on the use of the AstraZeneca vaccines against COVID-19 that is produced by different manufacturers (Astra Zeneca-Vaxzevria, Serum Institute India SII Covishield, and SK Bioscience).

The WHO continued to support the conclusion that the benefits of these vaccines outweighed the risks. More data had been obtained on the effectiveness of the vaccines in different population groups, such as older adults, making the evidence base more robust.