With the global expansion of the highly transmissible SARS-CoV-2 Delta (B.1.617.2) variant, we conducted a matched test-negative case–control study to assess the real-world effectiveness of COVID-19 messenger RNA vaccines against infection with Delta in Qatar’s population. BNT162b2 effectiveness against any, symptomatic or asymptomatic, Delta infection was 45.3% (95% CI, 22.0–61.6%) ≥14 d after the first vaccine dose, but only 51.9% (95% CI, 47.0–56.4%) ≥14 d after the second dose, with 50% of fully vaccinated individuals receiving their second dose before 11 May 2021. Corresponding mRNA-1273 effectiveness ≥14 d after the first or second dose was 73.7% (95% CI, 58.1–83.5%) and 73.1% (95% CI, 67.5–77.8%), respectively. Notably, effectiveness against Delta-induced severe, critical or fatal disease was 93.4% (95% CI, 85.4–97.0%) for BNT162b2 and 96.1% (95% CI, 71.6–99.5%) for mRNA-1273 ≥ 14 d after the second dose. Our findings show robust effectiveness for both BNT162b2 and mRNA-1273 in preventing Delta hospitalization and death in Qatar’s population, despite lower effectiveness in preventing infection, particularly for the BNT162b2 vaccine.

随着高度传播的 SARS-CoV-2 Delta (B.1.617.2) 变体在全球范围内的扩展，我们进行了一项匹配的测试阴性病例对照研究，以评估 COVID-19 信使 RNA 疫苗对感染的实际有效性与卡塔尔人口中的三角洲。BNT162b2 对任何有症状或无症状的 Delta 感染的有效性为 45.3% (95% CI, 22.0–61.6%) ≥14 d 在第一次疫苗接种后，但只有 51.9% (95% CI, 47.0–56.4%) ≥14 d在第二剂之后，50% 的完全接种疫苗的个体在 2021 年 5 月 11 日之前接受了第二剂。在第一剂或第二剂后 ≥14 天，相应的 mRNA-1273 有效性分别为 73.7%（95% CI，58.1-83.5%）和 73.1 %（95% CI，67.5–77.8%），分别。值得注意的是，BNT162b2 和 96 对 Delta 引起的严重、危重或致命疾病的有效性为 93.4%（95% CI，85.4-97.0%）。第二次给药后 14 天 mRNA-1273 为 1% (95% CI, 71.6–99.5%)。我们的研究结果表明，BNT162b2 和 mRNA-1273 在预防卡塔尔人口的 Delta 住院和死亡方面具有强大的有效性，尽管在预防感染方面的有效性较低，尤其是 BNT162b2 疫苗。