Suppose individuals react to the threat of getting infected by COVID by reducing their social activity. Denote person i'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 0,. The disutility an infection causes for person 1' is 1/0,. 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 2' is Pifaz', 51; P) EU(a,-,EL) :2 f(a,-) 9n; For simplicity use the following functional forms: p,- (at, a) = pafa, f(a'i) = at