Delta variant impact on June 21st easing – delay or reduce?

Having explored what pandemic advisers might be seeing and highlighting to decision-makers in Government, I run scenarios with different settings for the planned June 21st relaxation of lockdown, the last in the series of relaxations over the first half of 2021, following the January 3rd lockdown. These model scenarios show examples of what the relative consequences of the June 21st relaxation as planned, versus four other options:- cancellation of the June 21st step altogether, two different delays, of 28 and 56 days, and lastly a 50% reduction in the scope of the June 21st relaxation.

What are UK Government advisers seeing?

I have developed some model scenarios that show examples of what might be behind expert advice on the caution required with new SARS-Cov-2 variants. The scenarios indicate the importance of the UK vaccine programme, as we face variants with potentially different characteristics of transmission, severity of infection and responsiveness to vaccines. Understanding those variant characteristics is vital for projections.

Why the UK Government is worried about new variants

I have developed some model scenarios that show examples of what might be behind expert advice on the caution required with new SARS-Cov-2 variants. The scenarios indicate the importance of the UK vaccine programme, as we face variants with potentially different characteristics of transmission, severity of infection and responsiveness to vaccines.

Exploring new variants, vaccines and NPIs

There has been increasing concern recently about SARS-Cov-2 variants that might escape vaccines to some extent, as well as having different transmission rates (as the Kent variant does), and causing different severity of illness with higher mortality. I have added a vaccination efficacy modifier, var_eff, by variant, as a multiplier to the standard vaccination efficacy, vac_eff, to help model such potential variants that have a partial or total capability to escape vaccines, and this post shows examples of how that works, using a third variant introduced to the model on January 1st 2021. In addition, I have completed adding fSS (the fraction of people becoming seriously sick from each variant) and fmort (fatality of the variant) by Covid variant.

NPIs, variants and vaccine models

This paper reports some parametric Coronavirus model runs I have made that compare, in particular, how the UK vaccine programme allows some NPI relaxation compared with a case with no vaccination. The outcome is that the vaccine programme in the UK has the potential to reduce the imposition of NPIs on March 7th by about 15%, without costing lives, this being the next time we in the UK are due for a major NPI review, potentially involving the return of schools at around March 7th.