Scientists, including those from the University of Nottingham in the UK, noted that herd immunity develops when individuals contracting the disease build up natural immunity, and by people receiving a vaccine. When they factored in differences in age and social activity in the model, they found that the herd immunity level reduced from 60 to 43 per cent. This figure assumes that each individual in the population is equally likely to be vaccinated, and hence immune, the scientists explained. However, they said this is not the case if immunity arises as a result of disease spreading in a population consisting of people with many different behaviours. The researchers said the herd immunity level is lower when immunity is caused by disease spreading than when immunity comes from vaccination.

Source: Hindustan Times June 24, 2020 06:11 UTC