Expansion of SARS-CoV-2 Surveillance Required for Epidemic Prevention

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 (R_e).

The investigators observed there was an optimal strategy for every R_e 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 (R_e, 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.

With an increase of R_e 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 R_e is between 1.5 and 1.8 at which point the additional cost of the tests increases to $475.

At a R_e 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 R_e of 2.5, the frequency of testing should occur every day.

The most infectious scenario considered was a R_e 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 R_e is 1.5 (error, 0.72) and minimized when R_e 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.