In a 2020 Nature Medicine paper, the Weitz group led efforts to develop an epidemiological intervention model that leverages serological tests to identify and deploy recovered individuals who have developed protective antibodies to SARS-CoV-2. In this model, antibody-positive individuals serve as focal points for sustaining safer interactions via interaction substitution.
The objective of this intervention is to develop sufficient 'shield immunity' at the population scale to reduce epidemic intensity. Shield immunity works by increasing interactions with recovered individuals relative to individuals of unknown or susceptible status. Shield immunity can be utilized with social distancing measures, potentially enabling the same levels of infection reduction at the population scale with reduced economic and social costs of social distancing.
Despite the promise of shield immunity, there is a practical concern. How robust is the approach to variation in the specificity and sensitivity of antibody tests? In an ongoing collaboration, the Weitz and Lopman groups have evaluated the impact of the specificity and test capacity on both the reduction in disease transmission and the increase in the number of individuals who can safely return to work. As we show, highly specific tests (e.g., with upwards of 99% specificity) can reduce transmission while increasing the extent to which test status can help inform safer return to work policies. More information is available on our preprint.
We are currently working on new approaches to adapt shield immunity to healthcare settings. The key idea is to leverage serological tests and/or vaccinations to develop data- and epidemic-driven restaffing models to reduce risk of infection. Check back soon for more details.
While there are significant challenges to developing and implementing interventions that aim to build population-scale shield immunity, the magnitude of the current public health and economic crisis demands action, including new approaches to reopen schools and businesses. Our collaborative team continues to explore ways to assess the feasibility of shield immunity where recovered individuals may play a critical, active role in reducing the risk for others, alongside other measures including masks, social distancing, and test/tracing initiatives.