Sikuvi Kaveto, Nghitukwa Natasha, Kakehongo Ndiitodino, Katjitae Ismael, Matos Carolina, Oedi Philip, Netha Sibongile Manga, Nepolo Emmanuel, Winter Christian
Ministry of Health and Social Services Namibia, Ministerial Building, Harvey Street, Windhoek, Namibia.
Department of Medical Sciences, School of Medicine, University of Namibia, Windhoek, Namibia.
Vaccine. 2025 Mar 11:126977. doi: 10.1016/j.vaccine.2025.126977.
As of 24 October 2021, 128,868 laboratory-confirmed COVID-19 cases and 3550 deaths were reported from Namibia. The national COVID-19 vaccination campaign that started in March 2021 included health workers (HWs) as a priority group. The vaccines most administered were Sinopharm, AstraZeneca, Pfizer-BioNtech, and Janssen. We aimed to measure the effectiveness of COVID-19 vaccines (VE) amongst HWs against laboratory-confirmed SARS-CoV-2 infection in Namibia.
We conducted a test negative design (TND) amongst HWs from the two main hospitals treating COVID-19 patients. HWs were defined as all hospital staff over 18 years in direct or indirect contact with patients, eligible for COVID-19 vaccination. We interviewed actively recruited HWs with standardized questionnaires in-person from 25/10/2021 to 25/4/2022. The participants had to state their vaccination status, which was verified through vaccination card, vaccine registry and/or District Health Information System 2. RT-PCR testing of respiratory specimens and serological testing (Wantai and Platelia-ELISA) were conducted. We measured VE by comparing the vaccination status between RT-PCR positive and negative HWs using a multivariable logistic regression model, which was adjusted for confounders. We calculated VE = (1-odds ratio of vaccination)*100 %.
We included 1201 HWs of which 322 (26.8 %) participants were fully vaccinated with a primary series against COVID-19, 62 (5.2 %) were partially vaccinated and 735 (61.2 %) were not vaccinated. In total, 1119 (93 %) participants had antibodies against SARS-CoV-2 including 637 (90 %) of the unvaccinated participants. Fifty-eight (4.8 %) participants tested RT-PCR positive for SARS-CoV-2. The Omicron variant was detected in all 13 sequenced genomes (11 BA.1.18, 2 BA.1). The estimated overall VE for full vaccination was 61.8 % (95 %-confidence interval, 9.3-83.9 %).
The VE results suggest that COVID-19 vaccines used in Namibia provided good protection from infections with the Omicron variant even if many participants had a SARS-CoV-2 infection before the study. Therefore, COVID-19 vaccines should be administered to risk groups such as HWs independent from previous infections.
截至2021年10月24日，纳米比亚报告了128,868例实验室确诊的新冠病毒病病例和3550例死亡病例。2021年3月启动的全国新冠病毒疫苗接种运动将医护人员作为优先群体。接种最多的疫苗是国药集团疫苗、阿斯利康疫苗、辉瑞 - 生物科技疫苗和杨森疫苗。我们旨在衡量纳米比亚医护人员中新冠病毒疫苗针对实验室确诊的严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染的有效性。
我们在两家收治新冠病毒病患者的主要医院的医护人员中进行了检测阴性设计（TND）。医护人员定义为所有18岁以上直接或间接接触患者且有资格接种新冠病毒疫苗的医院工作人员。从2021年10月25日至2022年4月25日，我们采用标准化问卷对积极招募的医护人员进行了面对面访谈。参与者必须说明其疫苗接种状况，通过疫苗接种卡、疫苗登记册和/或地区卫生信息系统2进行核实。对呼吸道标本进行了逆转录聚合酶链反应（RT-PCR）检测和血清学检测（万泰及普泰利亚酶联免疫吸附测定法）。我们使用多变量逻辑回归模型，通过比较RT-PCR阳性和阴性医护人员之间的疫苗接种状况来衡量疫苗有效性，并对混杂因素进行了调整。我们计算疫苗有效性=（1 - 接种疫苗的比值比）×100%。
我们纳入了1201名医护人员，其中322名（26.8%）参与者完成了针对新冠病毒病的初级系列疫苗全程接种，62名（5.2%）为部分接种，735名（61.2%）未接种。总共有1119名（93%）参与者具有针对SARS-CoV-2的抗体，其中包括637名（90%）未接种疫苗的参与者。58名（4.8%）参与者的SARS-CoV-2 RT-PCR检测呈阳性。在所有13个测序基因组中均检测到奥密克戎变异株（11个BA.1.18，2个BA.1）。全程接种疫苗的估计总体疫苗有效性为61.8%（95%置信区间，9.3 - 83.9%）。
疫苗有效性结果表明，纳米比亚使用的新冠病毒疫苗即使在许多参与者在研究前已感染SARS-CoV-2的情况下，仍能为预防奥密克戎变异株感染提供良好保护。因此，应向医护人员等风险群体接种新冠病毒疫苗，而不考虑其既往感染情况。
