Getting to zero quickly in the 2019-nCov epidemic with vaccines or rapid testing

Gerardo Chowell; Ranu Dhillon; Devabhaktuni Srikrishna

If the current R is 2.2 or 3.9, 55% or 74% of the at-risk population, respectively, would need to be vaccinated in order to bring R below 1. If R is 2.2 and 10% of transmission occurs asymptomatically, approximately 60%, 68%, or 82% of symptomatic individuals would need to be tested and isolated for treatment within six, 24, or 48 hours, respectively, of symptom onset in order to bring R below 1. If asymptomatic transmission accounted for 20% of overall transmission, coverage would need to reach 65%, 74%, and 87% of the symptomatic individuals, respectively. If R is 3.9 and 10% of transmission occurs asymptomatically, testing with isolation and treatment would need to reach 83% or 93% of symptomatic individuals if done within six or 24 hours of symptom onset, respectively. Given that the denominator for population-wide vaccination (~10 million) is much greater than the proportion of that population with concerning symptoms, far fewer people would need to be reached with testing and isolation for treatment than for vaccinating to achieve herd immunity.