Coronavirus disease is a new virus that has never infected humans before. Humans have no immunity against it, so the virus spreads quickly. Herd immunity occurs when at least 70%-90% of a population have been infected and developed natural immunity against a disease, or have been vaccinated against it. Mass vaccination has eradicated smallpox from the world, and polio from several countries, including India. We are very far from herd immunity, according to World Health Organization. To contain coronavirus disease, at least 80% people must have antibodies for herd protection to kick in. Watch the full video for more details.