Correction to: Repeat SARS-CoV-2 testing models for residential college populations

Correction to: Health Care Manag Sci (2020)

10.1007/s10729-020-09526-0

The original version of this article unfortunately contained a mistake in the equation and reference. Thus, this erratum is presented to correct the errors.

In Chang et al. [1], eq. (12) was written as

$$Pr\left\{T>a\right\}={\int }_{t=a}^{\infty }\frac{\sigma \left(t\right)}{\tau }\prod _{k=1}^{⌊\frac{t}{\tau }⌋}\left(1-\sigma \left(t-\mathit{k\tau }\right)\right)\mathit{dt}\text{for}a>0.$$

This equation should be stated as

$$Pr\left\{T>a\right\}=1-{\int }_{t=0}^a\frac{\sigma \left(t\right)}{\tau }\prod _{k=1}^{⌊\frac{t}{\tau }⌋}\left(1-\sigma \left(t-\mathit{k\tau }\right)\right)\mathit{dt}\text{for}a>0.$$

These expressions are not identical because the density being integrated is improper — the integrand is the probability density for the time to isolation, but it is possible that an infection is never detected (that is, it is possible that T is infinite).

All numerical calculations in the paper are correct, and the associated app (https://jtwchang.shinyapps.io/testing/) does compute Pr{T > a} properly.