How effective is a single vaccine dose against corona?

The government is constantly changing its guidelines regarding Corona. Many changes have been made on behalf of the government regarding the vaccine. Between this question arises can a single dose Of Covid-19 vaccine protect us from the virus. On this, Dr. Shashank Joshi says that after applying a dose of vaccine, we get 70 percent protection. He further says percentage of protection for applying both doses of the vaccine increases significantly from 70. Watch video.