Category Archives: Alex de Visscher

Exploring the possible impact of the new variant Coronavirus

I cautiously welcomed “the end of the beginning”, and events since then have borne out the need for caution, with the discovery of a mutant variant of the SARS-Cov-2 virus (denoted VUI-202012/01) which seems to have a much greater transmission rate, as much as 70% more than the strain of SARS-Cov-2 we have seen previously in the UK. I have developed a further version of my Coronavirus model which now includes not only intervention capability but also a vaccination module, as reported before, and now the ability to add further virus strains with different transmission characteristics.

USA Thanksgiving Coronavirus lessons for UK Christmas and New Year?

We are aware that the rates of cases and deaths in the USA have increased steeply recently, and it seems that the natural public relaxation in precautions against Covid-19 for the Thanksgiving holiday period have exacerbated this. I have run my model with reductions to the USA intervention effectiveness during the Thanksgiving period (reflecting the increase in travel and social interactions in the USA) followed by reintroduction of the intervention effectiveness afterwards, to see the effect on the immediate projections. I have then applied similar changes to my UK models, to anticipate what the possible effect of such relaxations over the UK festive period might be. This is very much a sensitivity test of some scenarios, not a forecast.

The end of the beginning* – Coronavirus

Now that it seems clear that a vaccination programme in the UK might start as early as next week, I have re-run my Covid-19 vaccination model for the UK, updating the November 25th scenarios (which begin on January 1st 2021) to reflect some potential UK outcomes.

Vaccine, vaccine, vaccine, vaciiiine,…(don’t refuse it, just because you can)

In the news today, I read that Dolly Parton had given $1,000,000, through her Covid-19 Research Fund, to help fund the Moderna vaccine development. As The Times newspaper reported, this – erm – somewhat trumps the White House contribution to public safety. In her honour, Ryan Cordell composed and performed this ditty. The timing neatly coincides with the work I have been doing to incorporate vaccination into my Coronavirus model, and to that end I have been researching ways of modelling vaccination. I have made some appropriate changes, and run some model options for different vaccine efficacy; vaccinations per day; and date of starting the vaccination programme.

Where’s the exit? – Coronavirus

My title for this post is drawn from a slide I have shown before, from the 17th April Cambridge Conversation webinar, which I reported in my April 17th blog post, and also in my April 22nd blog post on model refinement, illustrating the cyclical behavior of the Covid-19 epidemic in the absence of pharmaceutical interventions, with control of cases and deaths achieved, only to some extent, by Non-Pharmaceutical Interventions (NPIs).

A brief look at Coronavirus model sensitivities to lockdown easing as we prepare for winter

The UK Government has just announced some reversals of the current lockdown easing, and so before I model the additional interventions announced today, I want to illustrate quickly the behaviour of the model in response to changing the effectiveness of current interventions, refecting the easings that have already been made, and also to highlight the sensitivity of the forecasts of case and death rates to the influence of lockdown effectiveness.

SARS-Cov-2 modelling situation report – Coronavirus

As we start September, the UK situation regarding Covid-19 cases and deaths has changed somewhat.

Since the UK Government re-assessed the way deaths data is collected and reported, the reported daily deaths resulting from Covid-19 infections have (thankfully) reduced to a very low level.

Cases, however, have started to rise again, although for a number of reasons the impact on deaths has been less than before. I have integrated the real world reported data with my model data to assess what is happening.

Coronavirus model updates for UK lockdown easing points

As I reported in my previous post on 31st July, the model I use, originally authored by Prof. Alex de Visscher at Concordia University on Montreal, and described here, was to be updated to handle several phases of lockdown easing, and I’m glad to say that is now done. Alex has been kind enough already to adopt a method I had been considering, of introducing an array of dates and intervention effectiveness parameters, and I have been able to add the recent UK Government relaxation dates, and the estimated effectiveness of each into a new model code. I have run two sets of easing parameters as a sensitivity test.

My model calculations for Coronavirus cases for an earlier UK lockdown

This post presents the two case number comparisons charts for the 9th March and 23rd March lockdown dates (I had covered the death data in more detail in my previous post on this topic).