Estimated Average Probabilities of COVID-19 Infection, Hospitalization, and Death From Community Contact in the United States

Bhatia, R.; Klausner, J.

Importance: Case and death counts, government rules limiting social contact, media attention, peer behaviors, and analogies to war have all influenced public perceptions of risk to COVID-19. During an epidemic, the general public may not be accurately interpreting their individual risks from COVID19. U.S. public sentiment surveys indicate a high level of apprehension about routine community activities. Sufficient data allow estimating individual-level probabilities of infection, hospitalization, and death from community level contacts. Objective: Our objective is to estimate the average probability of acquiring COVID19 infection, being hospitalized or dying from a single unprotected and substantive community level contact with an individual of unknown infection status. Design: We estimate individual level probability of a contact resulting in infection using established principles of infection transmission, published data on the secondary attack rate, the current case incidence, the infectious period, the proportion of asymptomatic infection, and the case hospitalization and infection fatality ratios. Setting: U.S. Counties Outcomes: Probabilities of COVID19 infection, hospitalization, and death from a single unprotected person-contact in a community setting. Results: Among the 100 most populous US Counties, the median probability of COVID19 infection transmission at the end of May 2020 is 1 infection per 3836 unprotected community-level contacts (Range: 626 to 31,800). For a 50 to 64 year old individual, the estimated median probability of hospitalization is 1 hospitalization per 852,000 community level person contacts (Range: 139,000 to 7,080,000). For a 50 to 64 year old individual, the median probability of a fatality is 1 fatality per 19.1million community-level person-contacts (Range,:3.13 million to 159,000,000 million). Conclusions and Relevance: Across the country, current probabilities of infection transmission, hospitalization, and death from COVID19 vary substantially, yet severe outcomes are still rare events. Individuals may be overestimating their risks of hospitalization and death and a moderate number and frequency of community contacts is unlikely to overwhelm hospital capacity in most U.S. settings. Systematic public reporting of COVID19 case incidence and prevalence of seropositivity by age, risk group, locality and setting would improve individual-level risk estimation.