Several COVID-19 vaccines have received emergency approval. Here we assess the immunogenicity of a single dose of the AZD1222 vaccine, at one month, in a cohort of health care workers (HCWs) (629 naïve and 26 previously infected). 93.4% of naïve HCWs seroconverted, irrespective of age and gender. Haemagglutination test for antibodies to the receptor binding domain (RBD), surrogate neutralization assay (sVNT) and ex vivo IFNγ ELISpot assays were carried out in a sub-cohort. ACE2 blocking antibodies (measured by sVNT) were detected in 67/69 (97.1%) of naïve HCWs. Antibody levels to the RBD of the wild-type virus were higher than to RBD of B.1.1.7, and titres to B.1.351 were very low. Ex vivo T cell responses were observed in 30.8% to 61.7% in naïve HCWs. Previously infected HCWs, developed significantly higher (p < 0.0001) ACE2 blocking antibodies and antibodies to the RBD for the variants B.1.1.7 and B.1.351. This study shows high seroconversion after one vaccine dose, but also suggests that one vaccine dose may be insufficient to protect against emerging variants.

几种 COVID-19 疫苗已获得紧急批准。在这里，我们在一组卫生保健工作者 (HCW)（629 名幼稚和 26 名先前感染）中评估了一个月内单剂 AZD1222 疫苗的免疫原性。无论年龄和性别，93.4% 的幼稚 HCW 都进行了血清转化。受体结合域 (RBD) 抗体的血凝试验、替代中和试验 (sVNT) 和离体 IFNγ ELISpot 试验在亚组中进行。在 67/69 (97.1%) 的初始 HCW 中检测到 ACE2 阻断抗体（通过 sVNT 测量）。野生型病毒 RBD 的抗体水平高于 B.1.1.7 的 RBD，而 B.1.351 的滴度非常低。在初始 HCW 中观察到 30.8% 至 61.7% 的离体 T 细胞反应。先前感染的 HCW 的发展明显更高（p < 0. 0001) B.1.1.7 和 B.1.351 变体的 ACE2 阻断抗体和 RBD 抗体。这项研究表明，一剂疫苗后血清转化率很高，但也表明一剂疫苗可能不足以防止出现新的变异。