first shipment of Covishield - the Covid-19 vaccine developed by AstraZeneca and Oxford University and manufactured by the Serum Institute of India, the second phase of the nationwide coronavirus vaccination dry run will be held today.During the day-long exercise, more than 25 health workers will get dummy vaccines at each site, which is meant to test the mechanisms and reveal possible gaps in the system ahead of the actual Covid vaccination drive.Also Read | Virus spread slows but two states still a worryWhat you need to know about nationwide Covid vaccine dry run:What is a dry run?A practice session, in which a sample number of beneficiaries will go through a mock immunisation process is known as a dry run essentially.Who will be.