Context: Recently, Bharat Biotech is getting into development and testing of a vaccine against COVID-19 called CoroFlu as part of an international collaboration of virologists and vaccine makers.
Background 

• CoroFlu is a one drop COVID-19 nasal vaccine built on a flu vaccine “backbone” that has been shown to be safe and well-tolerated in humans, in Phase I and Phase II clinical trials.

Key Findings

• The company said that the product is part of an international collaboration of virologists at the University of Wisconsin–Madison and vaccine companies FluGen along with Bharat Biotech. 
• CoroFlu will build on the backbone of FluGen's flu vaccine candidate known as M2SR. M2SR is a self-limiting version of the influenza virus that induces an immune response against the flu.
• Researchers will insert gene sequences from SARS-CoV-2, the novel coronavirus that causes the disease COVID-19, into M2SR so that the new vaccine will also induce immunity against the coronavirus. 
• Under the collaboration agreement, FluGen will transfer its existing manufacturing processes to Bharat Biotech to enable the company to scale up production and produce the vaccine for clinical trials. 
• Four Phase I and Phase II clinical trials involving hundreds of subjects have shown the M2SR flu vaccine to be safe and well tolerated.
• This safety profile, M2SR’s ability to induce a strong immune response, and the ability of influenza viruses to carry sequences of other viruses make M2SR an attractive option for rapidly developing CoroFlu as a safe and effective SARS-CoV-2 vaccine. 
• M2SR is a unique form of the flu virus. It lacks a gene called M2, which restricts the virus to undergoing only a single round of replication in cells. 
• CoroFlu, like M2SR, will be delivered intranasally. This route of administration mimics the natural route of infection by coronavirus and influenza and activates several modes of the immune system. 
• Intranasal delivery is more effective at inducing multiple types of immune responses than the intramuscular shots that deliver most flu vaccines.