Isolation thresholds for curbing SARS-CoV-2 resurgence.

Area of Science:

• Epidemiology
• Infectious Disease Modeling

Background:

• Self-instigated isolation is a primary non-pharmaceutical intervention for controlling severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission.
• Understanding the limits of isolation requires accounting for uncertainties in infection dynamics, including latent periods and asymptomatic cases.

Purpose of the Study:

• To estimate the effectiveness of self-isolation in curbing SARS-CoV-2 transmission during different phases of infection resurgence.
• To assess whether self-isolation alone was sufficient to control transmission in England by late 2020.

Main Methods:

• Modeling transmission dynamics of SARS-CoV-2.
• Incorporating uncertainty in latent and prepatent periods.
• Estimating the proportion of asymptomatic infections.

Main Results:

• By October 2020, SARS-CoV-2 transmission rates in England surpassed levels manageable by self-isolation alone.
• The effectiveness of self-isolation diminished as infection resurgence accelerated.

Conclusions:

• Self-isolation alone became insufficient to interrupt SARS-CoV-2 transmission in England by autumn 2020.
• These findings provide epidemiological support for the implementation of the second national lockdown on November 5th, 2020.