There is significant genetic distance between SARS-CoV-2 Omicron (B.1.1.529) variant BA.1 and BA.2 sub-lineages. This study investigates immune protection of infection with one sub-lineage against reinfection with the other sub-lineage in Qatar during a large BA.1 and BA.2 Omicron wave, from December 19, 2021 to March 21, 2022. Two national matched, retrospective cohort studies are conducted to estimate effectiveness of BA.1 infection against reinfection with BA.2 (N = 20,994; BA.1-against-BA.2 study), and effectiveness of BA.2 infection against reinfection with BA.1 (N = 110,315; BA.2-against-BA.1 study). Associations are estimated using Cox proportional-hazards regression models after multiple imputation to assign a sub-lineage status for cases with no sub-lineage status (using probabilities based on the test date). Effectiveness of BA.1 infection against reinfection with BA.2 is estimated at 94.2% (95% CI: 89.2–96.9%). Effectiveness of BA.2 infection against reinfection with BA.1 is estimated at 80.9% (95% CI: 73.1–86.4%). Infection with the BA.1 sub-lineage appears to induce strong, but not full immune protection against reinfection with the BA.2 sub-lineage, and vice versa, for at least several weeks after the initial infection.

SARS-CoV-2 Omicron (B.1.1.529) 变体 BA.1 和 BA.2 亚谱系之间存在显着的遗传距离。本研究调查了在 2021 年 12 月 19 日至 2022 年 3 月 21 日期间，在卡塔尔的 BA.1 和 BA.2 Omicron 大波期间，一个亚系感染对另一个亚系再感染的免疫保护。两个国家匹配，进行回顾性队列研究以估计 BA.1 感染对 BA.2 再感染的有效性（N = 20,994；BA.1-against-BA.2 研究），以及 BA.2 感染对 BA.1 再感染的有效性（ N = 110,315；BA.2-对-BA.1 研究）。在多重插补后使用 Cox 比例风险回归模型估计关联，为没有亚系状态的病例分配亚系状态（使用基于测试日期的概率）。BA的有效性。1 次感染对 BA.2 的再感染估计为 94.2%（95% CI：89.2–96.9%）。BA.2 感染对 BA.1 再感染的有效性估计为 80.9%（95% CI：73.1-86.4%）。BA.1 亚谱系的感染似乎在最初感染后的至少几周内诱导了针对 BA.2 亚谱系的再感染的强烈但不是完全的免疫保护，反之亦然。