Thread by @chrischirp

Short thread on case growth in Gauteng province, SA.

I compiled daily reported cases in November from sacoronavirus.co.za/category/daily… and had a look at growth...

TLDR pure omicron growth there looks pretty scary. We do NOT yet know how it will translate here. 1/7

Just plotting daily reported cases (dots) and the rolling centred average shows rapid increase in cases last few weeks of November. Blue dots are weekend reporting effects (Sundays and Mondays).

But for exponential growth we really need log scales... 2/7

Same chart on log scale looks like 2 periods of exp growth - one slower in 1st half Nov & then faster in 2nd half. Can interpret as period when Omicron gaining dominance over Delta (so smaller % of cases) & from 15th purer Omicron growth (now considered >90% of Gauteng cases) 3/7

Doing a *rough* fit of 2 exponentials to first and second half of Nov gets this. The bit that really matters is 2nd half of purer growth - this estimated growth is 25% a day, just over 3 day doubling. 4/7

They've been actively case finding in Gauteng & there've been superspreader events. So this is may be an overestimate. In UK, population much more vaxxed & boosted & loads of Delta around.

Also, this is pure Omicron growth - overall growth lower while Delta still there. 5/7

But even if growth is half of what has been observed so far in Gauteng (same chart as before on linear scale) if Omicron becomes dominant in UK (so 6 day doubling) that is still potentially very problematic.

Trick is to boost & vax as many as possible before then. 6/7

The more we slow growth of Omicron now, the more people we can protect. A few weeks makes a BIG difference and it's MUCH easier to do earlier rather than later.

Unfortunately, this means not waiting until we have vax experiment results in a few weeks. 7/7

PS Exactly what needs doing now depends on how widespread Omicron is here and how much community transmission. I don't that have info but govt, UKHSA & SAGE will have the best available knowledge.