Vaccine development company Serum Institute, India on Tuesday said the Covidshield vaccine will not be released for mass use unless it is proven immunogenic, and safe. The company also said the serious adverse event (SAE) that happened to a city-based volunteer though unfortunate was in no way induced by the vaccine.

Serum Institute, which had earlier said it would claim over `100 crore damage from the volunteer for damaging its reputation, said it was sympathetic with the volunteer's medical condition and the incident is highly unfortunate.