COVID insights - UK debate

Coronavirus may have infected half of UK population — Oxford study
https://ft.com/content/5ff6469a-6dd8-11ea-89df-41bea055720b 

This FT article briefly summarized the ongoing debate on the spread of COVID-19 in the UK. Oxford study is based on SIR model, a textbook method in epidemiology. As the results section of the paper cited in this article argued, one assumption in Oxford study is that only a small fraction of the population is at risk of severe disease which leads them to death. I understand the logic but to me this assumption sounds a bit too strong.

死に至るような人口は一部の高齢者など（人口の0.1~1%）に限られると仮定して、これだけ死んでいるのだから既に人口の半分近くが感染しているだろう、という想定でSIRモデルを立ててる、ちょっと強すぎる仮定にも見える。pをどこに設定するかは置いておくとして、このモデルが妥当であれば、高齢者割合が高い一方で死亡者が少ない日本のようなケースでは、まだ感染者割合はイギリスよりも少なそうだ。

Actually the letter to this article made a similar point. It seems Oxford study's assumption is not empirically supported. This suggests that Imperial College London study is more plausible? Not really. Their estimates were revised to downgrade the projected deaths a few days ago (source), so their results sound not so scary as it was before the estimates corrected.

結局のところ、論争になってるインペリアルカレッジの研究も推定値を修正しているし、オクスフォードの研究も仮定が経験的にサポートされてないし、注意深くみないといけないですね。