Vol.76 No.2

　著者らは，新型コロナウイルス（SARS-CoV-2）感染症（COVID-19）の発生と世界への拡散（パンデミック）の経緯およびCOVID-19の予防と治療に関するイベルメクチンの臨床研究について，中国湖北省武漢市におけるCOVID-19発生から15か月後の2021 年2 月に第3 波の流行が沈静化するまでの情報を収集・解析して和文および英文の総説を著述し，本誌に発表した。
　本総説では，その後の2 年2 か月間の第4 波～第8 波にわたるCOVID-19の世界的な推移に加えて，最も感染被害が大きかった米国の状況，各国間で異なる推移が認められた欧州とアジア，独特の推移が認められたインドおよび日本についてデータを収集して解析した結果を著述した。特に，COVID-19の最も顕著な特徴である変異株の出現と多種多様な亜型株への交代の様相，それら変異株および亜型株の病原性と感染性の強弱の相違を詳細に解析して記述した。
　COVID-19は流行の波が進むにつれて，感染力が強まり罹患者数が増大した半面で感染病態は軽度となる傾向があり，検査頻度の増加による罹患者発見の迅速化と多種の治療薬の導入による患者管理の改善が認められた。ワクチン接種の普及は極めて迅速であったが，SARS-CoV-2 の変異が速く，ワクチンによる感染拡大の防止効果は認められなかった。また，SARS-CoV-2 表層のスパイクタンパク質を標的とするモノクローナル抗体医薬は，標的が変異したことにより効果が減弱した。新規の治療薬の開発が進められており，COVID-19治療法は一層発展することが見込まれている。
　COVID-19パンデミックは鎮静化する傾向にあり，米国や日本では2023 年5 月には緊急事態への対応体制を解除した。世界各国で感染対策が緩和されつつあり，WHOもパンデミック宣言の年内終了を見込んでいる。今後，新たな変異株による流行の波が来襲しないことが望まれる。
　なお，本総説は，著者らによるイベルメクチンの臨床試験に関する次の総説の背景となる世界のCOVID-19の状況と治療薬の現状を解析したものである。

　The authors collected and analyzed information on the details of the outbreak and global spread (pandemic) of novel coronavirus (SARS-CoV-2) infection (COVID-19) and clinical studies of ivermectin for the prevention and treatment of COVID-19. The time period covered was until the third wave of the epidemic stabilized in February of 2021, which was 15 months after the COVID-19 outbreak in Wuhan, Hubei, China. Review articles were published, in Japanese and English, in this journal.
　This review describes the results of data collection and analysis of the global trends of COVID-19 from the fourth to the eighth wave in the ensuing two years and two months. The situations in the United States (most severely affected), Europe and Asia (where different trends were observed among countries), and India and Japan (where unique trends were observed), are also described. In particular, the emergence of variants, the most prominent feature of COVID-19—including subsequent transitions to various lineages, which strongly influence differences in the virulence and infectivity of mutant and subtype strains—is analyzed and described in detail.
　As the COVID-19 epidemic progressed, both the infectiousness of COVID-19 and the number of patients increased. However, the pathological course of clinical patients tended to become milder, and the disease prognosis less severe, as patient management improved with the introduction of various therapeutic agents, including rapid detection and increased frequency of testing. Although vaccination of the population progressed rapidly, SARS-CoV-2 mutated just as rapidly, rendering the vaccines less effective in both the prevention and spread of infection. In addition, monoclonal antibody drugs targeting the spike proteins on the surface of SARS-CoV-2 became less effective due to ongoing mutations involving the target receptors. Novel therapeutic agents continue to be developed, and further improvements in COVID-19 therapy are expected.
　The COVID-19 pandemic is currently on a downward trend, and the United States and Japan lifted their emergency pandemic response alerts in May of 2023. The WHO declared the termination of the Public Health Emergency of International Concern for COVID-19 on the 5th of May 2023. It is hoped that no new pandemic waves will appear in the future.
　This review provides the necessary background information for the next review by the authors on the clinical trials of ivermectin, by analyzing the status of COVID-19 worldwide and the current status of therapeutic agents being used.