COVID-19 testing strategies should be vastly expanded and should comprise more frequent, rapid testing and isolation strategies among individuals who test positive. These findings, from a multiscale modeling study, were published in the Lancet Public Health.

Using data on SARS-CoV-2 household-specific and age-stratified transmission data, researchers from the University of Texas in Austin simulated epidemic outbreaks for 150 days. Investigators tested individuals for COVID-19 at various frequencies (every 1, 7, 14, or 28 days) with 1- or 2-week isolation periods and assessed prevention of years of life lost (YLL) and cost effectiveness based on transmission rate (Re).

The investigators observed there was an optimal strategy for every Re value at increasing increments, assuming that every test costs $5 and a societal willingness to pay $100,000 for every averted YLL.

At low infection rates (Re, 1.1 or 1.2), testing should occur every 28 days and positive individuals should isolate for 1 week; the test should come at an additional cost of $75 and $125, respectively.


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With an increase of Re to 1.3 or 1.4, testing should occur every 14 days, at an additional $175 and $350, respectively. The testing frequency should shift to every 7 days when Re is between 1.5 and 1.8 at which point the additional cost of the tests increases to $475.

At a Re of 1.9, the isolation time for positive individuals should be increased to 2 weeks, and remain at 2 weeks for all high-infection scenarios. At a Re of 2.5, the frequency of testing should occur every day.

The most infectious scenario considered was a Re of 3.0. The optimal strategy in this situation was found to include daily testing at an additional cost of $275 and a 2-week isolation requirement.

The estimated probability of error for these models peaked when Re is 1.5 (error, 0.72) and minimized when Re is 3.0 (error, 0.18).

This study was limited by assuming infected individuals could not be reinfected. Much uncertainty about whether or not immunity from infection persists beyond the 5-month projection of this study. If immunity is not long-lasting, these estimates would be inaccurate.

These projected models indicated that SARS-CoV-2 surveillance programs should be widely expanded for long-term cost effectiveness and to reduce YLL.

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.

Reference

Du Z, Pandey A, Bai Y, et al. Comparative cost-effectiveness of SARS-CoV-2 testing strategies in the USA: a modelling study. Lancet Public Health. 2021;6(3):e184-e191. doi:10.1016/S2468-2667(21)00002-5.

This article originally appeared on Infectious Disease Advisor