3 (25 Marks)
The governments of the world are grappling with Covid 19 pandemic, several measures are being
implemented, namely, sanitizing, social distancing, hand-washing, working from home or online and
various forms of Lockdowns. The hope of all nations is to vaccinate at least 70% of the population to
reach head-immunity. This is based on Scientific advice, that once that population percentage is
immunized, the whole population would be protected, Economist call this positive externality in
consumption. With suitable diagrams, illustrate and discuss the phenomenon highlighted above.