Coronavirus Modelling Data Update: what's next?


So we will all have heard about the modelling data from Thursday night by now. I just want to touch on it a little bit tonight (sorry for delay). Prof Philip Nolan did a really fantastic discussion (every Thursday @ DOH briefing for those of you interested) about what has happened thus far and what might happen in future.


It’s NB to know that models are very useful, But they make KEY ASSUMPTIONS & if they are wrong then things can go awry. They are no substitute for good public health decision making. Because we are constantly getting new data they are constantly changing and the more data we have the better they will be.


Looking back, at the beginning we know the disease was Growing at 33% per day. But it has significantly changed - growth rate and in hospital admissions; Same for ICU admissions. The number of deaths has increased but the rate of growth in deaths has slowed - it will be very NB to watch this over the next week


Looking into the future we will need to look at

  • Growth rate cumulative cases - stable at 5% over a week

  • Growth rate new cases - changing but averaging over 5 days is good


He stated that there is very little growth of epidemic in community at this stage which is FANTASTIC news. Most of the measures we look at are stable since the 3rd April which is good.


The most important figure though realistically going forward is the R0, or the amount of people 1 person who has the virus infects. This is key to what happens going forward. We have 4 separate ways of estimating R0 and thankfully Over the last few days it has been between 0.7 and 1 (all 4 levels showing below this!). This is AMAZING. But Jesus this DOES NOT MEAN we can become complacent.


R0 at different stages of epidemic

Early stages R0 = 2-4 (no measures in place)

After early interventions (schools closed) R0 = 1.5-3

After lockdown until now R0 below 1.


They were optimistic at the press conference, but you need to listen carefully. It took these “lockdown measures” to get the R0 to below 1 & this is where we need it to stay if we are to keep this disease under control.


So if we are thinking of relaxing measures we need to make sure we don’t go back to these higher numbers.


If for example the R0 was...


R0 3.7 = Unmitigated epidemic - 120,000 infections in community this week


If we had only reduced to 2.4 (partially mitigated epidemic so initial closure of schools etc) then 70000 infections, 7800 new cases today, 800 in ICU, total 1700 deaths by next week


But the measures taken on 28 March (“lockdown”) have stoped this from happening.

It’s so important that we suppress this disease and keep R0 at or really close to 1 (ideally R0 0.6 or so!)


We are hopeful that we are now below 1.0 and that we are at our peak / plateau & we should start seeing decline in cases over the next few weeks...

If we ease measures on 5th May we need to be able to assume / model what will happen & this all comes down to the R0 increasing or not. So we have to mange what happens exceptionally carefully as we cannot manage a huge rise in cases.


So if for example we relax the measures slightly for 3 weeks, depending on what happens to R0 we may need to reimpose measures. If R0 doesn’t go above 1.1 then we might get another slight peak & we reimpose Measures to control it. If it goes to 1.6 then we would see a significant increase in cases). If it goes back above 2 we get a sudden almost certainly unmanageable spike in disease


So, how do we go about activities of living safely? How can things be done with low risk of transmitting virus? THIS IS THE REAL QUESTION. Through distancing, hygiene and control of droplets from nose & mouth. These control Measures are with us to stay until a vaccine hopefully becomes available.


Lots of you ask How can kids go back to school without increasing the R0? Very high risk activity for example. I’m not sure I see the DOH recommending this anytime soon, but we need to see what happens in other countries that are beginning to lift restrictions now. And if they increase the figures then further restrictions will have to be brought back


The one thing I know is that we are going to require a very strong number of measures for a prolonged period of time to keep this disease under control in our society


An increase to R0 of 1.2 would put us on a unsustainable track. So we have to be ready to pick up ANY infections when we relax measures with stringent testing and contact tracing. I’m not sure we are there yet either. After the 5th of may it might happen that we suggest using masks in every day life when out in public for example To allow us to live with some relaxation of measure and continue to protect others.


The challenge going forward will be to work out how we can keep R0 at or below 1 without these stringent measures in place. Let me know over on the instagram post what you think.


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DR LAURA LENIHAN MICGP BM BS, MSc, B. Comm. IMC 406336

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