Aim

To evaluate anti-RBD IgG antibody levels and neutralizing antibody titers between the health care workers (HCWs) with breakthrough SARS-CoV-2 infection and controls.

Methods

In this nested case-case control study, we followed 548 vaccinated HCWs with homologous (only with inactivated vaccine) or heterologous (both with inactivated and BNT162b2 vaccine) vaccination for 11 months, prospectively. We obtained blood samples from the participants for quantitative anti-RBD IgG and surrogate neutralization test. The participants with SARS-CoV-2 PCR positivity (at least 14 days after the last vaccination) were considered breakthrough infection. We chose 1:2 matched controls from the cohort, according to age, sex and vaccination status. We used R version 4.0.2 for the statistical analysis.

Results

Sixty-five cases and 130 controls were included in the study. The number of the breakthrough infections in HCWs were correlated with the pandemic waves in Türkiye and peaked during Omicron outbreak. The median age of the cases was 39 and 78.5% were female. The cases had more comorbidities than controls, significantly (p = 0.021). All cases experienced no or mild symptoms and recovered completely. Both pre-infection anti-RBD antibody and neutralizing antibody titers did not differ between cases and matched controls (p = 0.767, p = 0.628).

Conclusion

In this study, we showed that there was no comparable difference in humoral response after homologous or heterologous vaccination between the cases of breakthrough infection and matched controls. Compliance with infection control measures should be ensured, in combination with vaccination.

中文翻译：

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SARS-CoV-2突破性感染的已接种疫苗的医护人员的感染前抗体水平：一项巢式病例对照研究

目的

评估突破性 SARS-CoV-2 感染和对照的医护人员 (HCW) 之间的抗 RBD IgG 抗体水平和中和抗体滴度。

方法

在这项巢式病例对照研究中，我们对 548 名接种过同源疫苗（仅使用灭活疫苗）或异源疫苗（均使用灭活疫苗和 BNT162b2 疫苗）的医护人员进行了为期 11 个月的前瞻性跟踪。我们从参与者那里获取了血液样本，用于定量抗 RBD IgG 和替代中和测试。SARS-CoV-2 PCR 呈阳性的参与者（最后一次疫苗接种后至少 14 天）被视为突破性感染。我们根据年龄、性别和疫苗接种状况从队列中选择 1:2 匹配的对照。我们使用 R 版本 4.0.2 进行统计分析。

结果

该研究包括 65 例病例和 130 例对照。医护人员的突破性感染数量与土耳其的大流行浪潮相关，并在 Omicron 疫情期间达到顶峰。病例的中位年龄为39岁，78.5%为女性。病例的合并症明显多于对照组（p  = 0.021）。所有病例均无症状或症状轻微，并完全康复。感染前抗 RBD 抗体和中和抗体滴度在病例和匹配对照之间没有差异（p  = 0.767，p  = 0.628）。

结论

在这项研究中，我们表明，突破性感染病例和匹配对照之间，在同源或异源疫苗接种后，体液反应没有可比差异。应确保遵守感染控制措施并结合疫苗接种。