BA.2 – A rambling mind

They think it’s all over – but it isn’t

Chart 318 for scenario UK_994 with adult vaccinations, and vacs for 5-11 year-olds from April 1st 2022. 24th February NPI -79.64% reduction. Omicron BA.1 transmission k11 = 6. BA.2 k11 = 8, var_eff = 25/50/70%, fSS 3% and fmort 1.05%. Model outcomes to December 3rd 2023. Reported active cases and deaths to 19th April 2022. Serious cases for 5 variants.

In this article, I present a few variations of the current model to illustrate some outcomes depending on different assumptions about the current dominant variant, Omicron BA.2; they are fairly consistent in their forecasts over the 1400 day period of the model, from the outset in February 2020 to December 2023, and show that as NPIs are removed, vaccination is what keeps us safe.

Omicron BA.2, vaccination for 5-11 year-olds, and the honeymoon period

Chart 318 for scenario UK_701 with adult vaccinations and 5-11 vacs from April 1st 2022. 17th May 1.8% ,19th July 1%, 1st Sep 2%, mean NPI relaxations and 30th Nov +2% and 10th Dec +3% additional NPIs. Omicron v4 transmission k11 = 6, BA.2 v5 k11 = 8, var_eff = 25/50/70%, fSS 7% and fmort 1.05%. Model outcomes to December 3rd 2023. Reported active cases and deaths to February 19th 2022. Serious cases for 5 variants.

I haven’t needed to make significant updates to my Coronavirus model for a while, because it has been working well.
The original Omicron variant morphed into the new BA.2 variant, and although it seems no more dangerous than its predecessor, it is thought to be between 33%-50% more transmissible. I have assumed the lower value of 33% more transmissive for this post.
I have added Omicron BA.2 as fifth variant v5 to my model, with 8 times the transmissibility of Delta, compared with the original Omicron variant v4 in the model, at 6 times the Delta transmission rate.