指数関数的な成長,SARS-CoV-2の高い流行,デルタ型に関連したワクチンの有効性
Paul Elliott1,2,3,4,5,6, David Haw1,7, Haowei Wang1,7
1School of Public Health, Imperial College London, London, UK.
まとめ
デルタ変種は2021年夏にイングランドでSARS-CoV-2感染が急増し,ワクチン接種を受けていない若者の罹患率が高くなりました. それにもかかわらず,COVID-19ワクチンは感染に対して50~60%の有効性を示しました.
科学分野:
- 流行病学について
- 感染症
- ワクチン学
背景:
- SARS-CoV-2デルタ型の出現は,2021年初夏に世界中で感染が増加した.
- 感染の動態とワクチンの有効性を理解することは,公衆衛生戦略にとって極めて重要です.
研究 の 目的:
- イングランドにおけるデルタ変異の急増の際にSARS-CoV-2スランプ陽性の傾向を評価する.
- ワクチン接種状況が感染率に与える影響を評価し,ワクチンの有効性を推定する.
主な方法:
- イギリスにおける"地域感染のリアルタイム評価" (REACT-1) のデータを使用した.
- 2021年6月から7月の反転転写ポリメラーゼ連鎖反応 (RT-PCR) スワンプ陽性率を分析した.
- ワクチン接種と未接種の比率,人口統計的要因を調整した.
主要な成果:
- 感染の指数関数的な増加が観察され,平均倍増時間は25日です.
- デルタ変種はアルファ変種を完全に置き換え,感染拡大に貢献した.
- 予防接種を受けていない個体では,二重予防接種を受けた個体と比較して,罹患率が3倍であった (1. 21% 対 0. 40%).
- 感染に対するワクチンの有効性は,二回接種した個体では50%から60%と推定された.
結論:
- 社会的混雑が増加し,デルタ変異の優位性は,高度にワクチンを接種した集団でも感染の増加を助長した.
- ワクチン接種は感染率を大幅に低下させましたが,感染の伝播を排除することはできず,継続的な監視と制御措置の必要性を強調しました.
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