小野京右（東京工業大学名誉教授）2023年12月5日
３年半近くの長い期間全世界を恐怖に陥れた新型コロナウイルス感染症が，５月に５類に移行しました．10月16~19日に第10回日経・FT感染症会議が行われ，今後の課題が議論されました．なんといってもこれまでの度重なる流行の波が如何に起こり，どのように対処されてきたのかを科学的に分析し，更にどうすればよかったのかを示すことが重要でしょう．このブログでは「東京都における新型コロナ感染症の第５波感染拡大・縮小過程のIR理論による解析」と題してオリンピック開催に同期して拡大・縮小した第５波についての主原因は何かについて論じました．この論文の英論文は掲載料零のOpen- accessの国際誌IJEHSに掲載したところ，外国での評価は高く，その後現在に至るまで，月数件の投稿依頼等が来ています．その一例を示します．
Dear, Dr Kyosuke Ono
Greetings from the “Journal of Clinical Case Reports and Trails” an open-access worldwide platform, publishing recent scientific information on the relevant subject.
We appreciate your professionalism, deep insight, and understanding of the subject of Clinical case reports after reading your article “Numerical Analysis of the Fifth Wave of COVID-19 epidemic in Tokyo, Japan. We would like to invite you to submit your expert commentary/review articles based on your previous scientific endeavors, and your current scientific research in the form of unpublished articles (i.e., Abstracts, Book Reviews, Case Reports, Editorial letters, Research Articles, and Short Communication) falling under the scope of the journal.
Medires Publishing LLC accepts manuscript submissions through a submission portal on our website or as an email attachment. We hope that your valuable research contributions will serve the motto of our organization and achieve our common goal of boosting global research by providing open access to your expert articles.
これらの要望に応えたいとの意識から，共同研究者である大学時代の友人，菊地勝昭氏
（元日立製作所副技師長）とこの４カ月ばかり第6,7,8波の解析と対策についての英論文をまとめ，恐らく感染症理論分野ではトップレベルのAnnals of Epidemiology (Elsevier)に投稿しました．その日本語タイトルは「東京都における新型コロナCOVID-19感染症流行の第６，７，８波の数理解析と検査人数制御法による感染流行抑圧効果」です．私どもは感染症については素人ですが，工学解析の専門家として，新型コロナウイルス感染症流行現象を科学的に分析し，その抑圧対策を提案したものです．日本語の論文は英論文が採用されてからOpenしますが，以下にその要約を記します．本研究が提案する新IR理論とこれに基づく数値解析法，感染を抑圧する検査人数制御法が今後同様の感染症の流行が生じた際に各国で使用されることを願っています．
Abstract.
From December 2021 to March 2023, Japan experienced the 6th, 7th and 8th waves of the COVID-19 epidemic. This paper first formulates a new IR epidemic theory in which I and R include exposed and symptomatic persons. The new IR model was applied to the analysis of the 6th, 7th and 8th wave epidemics in Tokyo, the city with the largest number of cases in Japan. The transition of infected persons in the city, the infection rate, the removal rate, and the effective reproduction number were clarified on the basis of the available data on daily positive cases Rd. In particular, in the 6th wave of the omicron-BA.1 type epidemic, the effective reproduction number increased rapidly to 2.4, in the early stage of expansion, and the number of positive cases increased to 3.6 times that of the 5th wave due to the delay in the testing system and the shortage of test kits, resulting in a tightening of the medical system. In the 7th wave, the testing systems were significantly strengthened. However, the high infectivity of the omicron variants resulted in more positive cases, 6.6 times as many. The effect of vaccination on the suppression of infection rate and reproduction number was also assessed by considering changes in vaccination rates and loss of effectiveness over time with second, third and fourth booster doses. As a countermeasure to suppress the spread of infection, we proposed the T control method, in which the number of persons tested T is increased in proportion to the daily rate of increase in Rd. We simulated the effect of applying the T control method to the 6th, 7th and 8th waves using the measured relationship between the removal rate and the number of persons tested in each wave. The results showed that for the 6th wave, the maximum value of Rd could be reduced to less than one tenth to one half of the actual value three to two weeks earlier if the T control method was applied 10 to 27 days after the start of the expansion. In the 7th and 8th waves, the testing regime was significantly tightened compared to the 6th wave. However, if the T control was applied within 10 days of the start of expansion, the maximum Rd could be reduced to less than half of the actual maximum value. The theoretical analysis of infectious disease epidemics based on the new IR model and the T control method will be a powerful tool to suppress infectious disease pandemics with high infection rates in the future.
