Early vaccine implies strict social distancing optimal

March 01, 2021

Since the COVID pandemic hit last year, policymakers have been faced with a difficult choice: which social distancing policies should be implemented, and for how long should they remain in place? While stricter policies reduce the spread of the virus, thus decreasing initial mortality and the present costs associated with increased infection, researchers must balance them with economic and social costs over time. How such policies impact society also depends on estimates of “vaccine arrival,” defined as the time to develop and widely distribute a vaccine, to the point that social distancing policy is no longer needed.

New research co-authored by Larry Karp, a professor in the Department of Agricultural and Resource Economics, suggests that in the present U.S. context—when vaccines have been approved and are in the early stages of distribution—stricter social distancing policies are optimal. The study, titled “Optimal Social Distancing and the Economics of Uncertain Vaccine Arrival,” appeared in the latest issue of ARE Update, a bimonthly publication of the Giannini Foundation of Agricultural Economics that educates policymakers and agribusiness professionals on important topics in agricultural and resource economics.

To evaluate the costs and benefits of a strict social distancing policy, the authors use various estimates for vaccine arrival time and deploy a modified version of a common model in epidemiology research: the Susceptible-Infected-Recovered (SIR) model. It assesses the population as a network of susceptible individuals, then shows how individuals within the population move from infected to recovered under different social distancing parameters, before considering how recovery affects the population. The models allow the researchers to assess the benefits of reducing infection in the present with the risk of greater susceptibility in the future.

The authors also evaluate proposals like the Great Barrington Declaration, which recommends moving quickly to herd immunity through the removal of most social distancing policies. They find that, particularly when an early vaccine arrival is expected, promoting herd immunity leads to much higher combined economic and mortality costs, as compared to the optimal social distancing policy.

Learn more about the effects of vaccine arrival time on optimal social distancing policy from the full study.  

This article was adapted from a press release from ARE Updates.