Introduction:
The Serum Institute of India is currently developing the Covishield vaccine.

Explanation:
- The Covishield vaccine is being developed by the Serum Institute of India.
- It is a vaccine against COVID-19.
- The Serum Institute of India is the world's largest vaccine manufacturer by volume, and it has partnered with AstraZeneca and the University of Oxford to produce the Covishield vaccine.
- The vaccine is based on a viral vector platform, which uses a harmless adenovirus to deliver a modified version of the spike protein found on the surface of the SARS-CoV-2 virus.
- The spike protein is responsible for the virus's entry into human cells, and by targeting it, the vaccine triggers an immune response without causing the disease.
- The Covishield vaccine has undergone various stages of clinical trials to evaluate its safety and effectiveness.
- The vaccine has been granted emergency use authorization in several countries, including India, where it is being widely used in the national vaccination campaign.
- The Covishield vaccine has shown promising results in preventing COVID-19 and reducing the severity of the disease.
- It requires two doses to achieve optimal protection, with an interval of 4 to 12 weeks between doses.
- The vaccine has been proven to be effective against multiple variants of the SARS-CoV-2 virus, including the Alpha, Beta, and Delta variants.
- The Covishield vaccine has played a crucial role in the global vaccination efforts, as the Serum Institute of India has been supplying it to many countries around the world.

Conclusion:
In conclusion, the Serum Institute of India is developing the Covishield vaccine, which has shown effectiveness against COVID-19 and has been widely used in the vaccination campaigns in India and other countries.