Climate Etc.

By Nic Lewis

An interesting new paper by Marc Lipsitch and co-authors, “Cross-reactive memory T cells and herd immunity to SARS-CoV-2”, has recently been published.[1] It discusses immunological and epidemiological aspects and implications of pre-existing cross-reactive adaptive immune system memory arising from previous exposure to circulating common cold coronaviruses. They argue that key potential impacts of cross- reactive T cell memory are already incorporated into epidemiological models based on data of transmission dynamics, particularly with regard to their implications for herd immunity. I believe that they are mistaken on the herd immunity point, as I will show in this article. Continue reading →

By Nic Lewis

I showed in my May 10th article Why herd immunity to COVID-19 is reached much earlier than thought that inhomogeneity within a population in the susceptibility and in the social-connectivity related infectivity of individuals would reduce, in my view probably very substantially, the herd immunity threshold (HIT), beyond which an epidemic goes into retreat. Continue reading →

By Nic Lewis

Much fuss has been made in the UK, not least by teachers’ unions, about recommencing physical school attendance. As this issue applies to many countries, I thought it worth highlighting research findings in Europe. Continue reading →

by Judith Curry

It’s time for a politics thread, to deflect the political comments that are sneaking into the technical threads.

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by Judith Curry

Some additional articles and events to discuss.

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By Nic Lewis

I showed in my May 10th article Why herd immunity to COVID-19 is reached much earlier than thought that inhomogeneity within a population in the susceptibility and in the social-connectivity related infectivity of individuals would reduce, in my view probably very substantially, the herd immunity threshold (HIT), beyond which an epidemic goes into retreat. I opined, based on my modelling, that the HIT probably lay somewhere between 7% and 24%, and that evidence from Stockholm County suggested it was around 17% there, and had been reached. Mounting evidence supports my reasoning.^[1]

I particularly want to highlight an important paper published on July 24th “Herd immunity thresholds estimated from unfolding epidemics” (Aguas et al.).^[2] The author team is much the same as that of the earlier theoretical paper (Gomes et al.^[3]) that prompted my May 10th article. Continue reading →