Modeling shield immunity to reduce COVID-19 epidemic spread

TLDR

The COVID‑19 pandemic has triggered a global crisis, prompting mitigation and suppression strategies that aim to curb infections by limiting human interactions, though such measures may be socially and economically unsustainable long term. The study proposes a shield‑immunity strategy that uses recovered individuals to maintain essential interactions while lowering transmission risk. An epidemiological model was developed that employs serological testing to identify recovered persons and deploy them as focal points for safer interaction substitution, creating population‑scale shield immunity. The model shows that shield immunity can substantially shorten the outbreak and reduce its burden, works synergistically with social distancing, and underscores the importance of serological testing beyond prevalence estimation and plasma therapy development.

Abstract

The COVID-19 pandemic has precipitated a global crisis, with more than 1,430,000 confirmed cases and more than 85,000 confirmed deaths globally as of 9 April 20201-4. Mitigation and suppression of new infections have emerged as the two predominant public health control strategies5. Both strategies focus on reducing new infections by limiting human-to-human interactions, which could be both socially and economically unsustainable in the long term. We have developed and analyzed an epidemiological intervention model that leverages serological tests6,7 to identify and deploy recovered individuals8 as focal points for sustaining safer interactions via interaction substitution, developing what we term 'shield immunity' at the population scale. The objective of a shield immunity strategy is to help to sustain the interactions necessary for the functioning of essential goods and services9 while reducing the probability of transmission. Our shield immunity approach could substantively reduce the length and reduce the overall burden of the current outbreak, and can work synergistically with social distancing. The present model highlights the value of serological testing as part of intervention strategies, in addition to its well-recognized roles in estimating prevalence10,11 and in the potential development of plasma-based therapies12-15.