Thread by @IronEconomist

I regret to inform you that what is happening in Manaus should scare everyone witless. theguardian.com/world/2021/jan…

It looks from the reports like all cause mortality is currently running ~6x normal in a population that is 90% under fifty. But worse, Manaus already achieved herd immunity, and certainly a high level of infections.

Levin et all applied their age specific mortality to a sero-study of 66% and got similar expectations to actual fatalities give the age structure. Good conditional evidence the sero study was ~accurate despite some sampling flaws.

So if Manaus has 70% immunity and yet is over run worse than march, then it isn’t enough for it to be more transmissible like the UK variant. The 70% reduction from immunity would more than balance it compared to march.

There are therefore two possibilities: (1) it is evading acquired immunity and (2) It is not only more transmissible but much more severe as well, and so is causing hospitalisations to be over run with a smaller number of infections.

This is extremely bad: I repeat, if the Brazilian strain is not evading acquired immunity, the it must be a dramatically worse virus. If it is evading acquired immunity then either immunity is transient or it’s an immunologically distinct strain.

Everyone should be taking this extremely seriously.