Suppose individuals react to the threat of getting infected by COVID by reducing their social activity. Denote person 73's level of social activity as a,- E [0.1]. Further denote the average activity level in the society as (1. A person's resilience to the virus is given by 6,. The disutility an infection causes for person 2' is 1/9,. Finally, the infectiousness of the current variant is given by p. A person chooses her activity level in order to maximize her enjoyment from social activity net of expected health consequences of an infection. The probability p, of contracting the virus depends on activity level, average activity level in the society and on the infectiousness of the variant. Hence, the objective function of person i is Pdai: (1; P) EU(a,-,Et) 2: f(a,-) 9i For simplicity use the following functional forms: 23. (at, a) = paEc'z, at) = a