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Polio 2022

Recall that polio spreads mostly through the faecal route, i.e. through contaminated water. Preventable by vaccination and (almost) eradicated by mass vaccination campaigns:

Still present in some countries in the world:

but “endemic” in only a few countries although largely declining as vaccination cover and hygiene improve:

Hopefully only few cases in London.

Monkeypox: update on June 22nd, 2022

UK data: red and black points: UKHSA data, blue points: OWD data (shifted by 11 days), solid line: model

What a difference a couple of days make! When on Monday I was finishing the analysis underlying my new The Conversation article, I was expecting the monkeypox epidemic to start fizzling off. Indeed, the Our World in Data records were showing a flattening of the disease progress on Monday and Tuesday.

Then, yesterday (June 21st, 2022) brought a bombshell of a 38% increase in the new cases reported in the UK. Does this increase change my analysis?

I am going to stick to Scenario 3 which I think represents best the current situation. In that scenario, there is a core group sized N among whom the virus is spreading. In addition, there is an exchange of members of that group with the larger population by which the individuals who are immune move out of the group and are replaced with new individuals who are susceptible.

I believe this captures the current dynamics best, with the core group largely composed of Men who have Sex with Men (MSM) with some spillover to the general population but without a substantial community spread.

The current key parameters are N=1200 (a slight increase from the original piece of N=1000), \beta=0.59 (a slight decrease from \beta=0.6) and d=1/60 (same as before, meaning one person swapping on average every 2 months).

The model still seems to work, although the most recent jump is underestimated. It remains to be seen what happens in the next few days and weeks. I am still quite optimistic and think that with vaccination we might move back to Scenario 1 and finish the epidemic shortly. However, it is not inconceivable that we might move to an endemic situation.