PDF(Pubmed)
Abstract：
The study aim was to evaluate vaccine effectiveness (VE) of COVID-19 vaccines in preventing symptomatic COVID-19 among healthcare workers (HCWs) in Zambia. We sought to answer the question, \'What is the vaccine effectiveness of a complete schedule of the SARS-CoV-2 vaccine in preventing symptomatic COVID-19 among HCWs in Zambia?\'
We conducted a test-negative case-control study among HCWs across different levels of health facilities in Zambia offering point of care testing for COVID-19 from May 2021 to March 2022.
1767 participants entered the study and completed it. Cases were HCWs with laboratory-confirmed SARS-CoV-2 and controls were HCWs who tested SARS-CoV-2 negative. Consented HCWs with documented history of vaccination for COVID-19 (vaccinated HCWs only) were included in the study. HCWs with unknown test results and unknown vaccination status, were excluded.
The primary outcome was VE among symptomatic HCWs. Secondary outcomes were VE by: SARS-CoV-2 variant strains based on the predominant variant circulating in Zambia (Delta during May 2021 to November 2021 and Omicron during December 2021 to March 2022), duration since vaccination and vaccine product.
We recruited 1145 symptomatic HCWs. The median age was 30 years (IQR: 26-38) and 789 (68.9%) were women. Two hundred and eighty-two (24.6%) were fully vaccinated. The median time to full vaccination was 102 days (IQR: 56-144). VE against symptomatic SARS-CoV-2 infection was 72.7% (95% CI: 61.9% to 80.7%) for fully vaccinated participants. VE was 79.4% (95% CI: 58.2% to 90.7%) during the Delta period and 37.5% (95% CI: -7.0% to 63.3%) during the Omicron period.
COVID-19 vaccines were effective in reducing symptomatic SARS-CoV-2 among Zambian HCWs when the Delta variant was circulating but not when Omicron was circulating. This could be related to immune evasive characteristics and/or waning immunity. These findings support accelerating COVID-19 booster dosing with bivalent vaccines as part of the vaccination programme to reduce COVID-19 in Zambia.
We conducted a test-negative case-control study among HCWs across different levels of health facilities in Zambia offering point of care testing for COVID-19 from May 2021 to March 2022.
1767 participants entered the study and completed it. Cases were HCWs with laboratory-confirmed SARS-CoV-2 and controls were HCWs who tested SARS-CoV-2 negative. Consented HCWs with documented history of vaccination for COVID-19 (vaccinated HCWs only) were included in the study. HCWs with unknown test results and unknown vaccination status, were excluded.
The primary outcome was VE among symptomatic HCWs. Secondary outcomes were VE by: SARS-CoV-2 variant strains based on the predominant variant circulating in Zambia (Delta during May 2021 to November 2021 and Omicron during December 2021 to March 2022), duration since vaccination and vaccine product.
We recruited 1145 symptomatic HCWs. The median age was 30 years (IQR: 26-38) and 789 (68.9%) were women. Two hundred and eighty-two (24.6%) were fully vaccinated. The median time to full vaccination was 102 days (IQR: 56-144). VE against symptomatic SARS-CoV-2 infection was 72.7% (95% CI: 61.9% to 80.7%) for fully vaccinated participants. VE was 79.4% (95% CI: 58.2% to 90.7%) during the Delta period and 37.5% (95% CI: -7.0% to 63.3%) during the Omicron period.
COVID-19 vaccines were effective in reducing symptomatic SARS-CoV-2 among Zambian HCWs when the Delta variant was circulating but not when Omicron was circulating. This could be related to immune evasive characteristics and/or waning immunity. These findings support accelerating COVID-19 booster dosing with bivalent vaccines as part of the vaccination programme to reduce COVID-19 in Zambia.
摘要：
目的：研究的目的是评估COVID-19疫苗在预防赞比亚医护人员（HCWs）中有症状的COVID-19中的疫苗有效性（VE）。我们试图回答这个问题，
方法：我们从2021年5月至2022年3月，在赞比亚不同级别的医疗机构中，SARS-CoV-2疫苗的完整时间表在预防有症状的COVID-19方面的疫苗有效性如何？
方法：1767名参与者进入研究并完成研究。病例为实验室确诊的SARS-CoV-2的HCWs，对照组为SARS-CoV-2阴性的HCWs。这项研究包括了有COVID-19疫苗接种史的同意的HCWs(仅限接种疫苗的HCWs)。具有未知测试结果和未知疫苗接种状态的HCWs，被排除在外。
方法：主要结局是有症状的HCWs中的VE。次要结果是VE：基于在赞比亚流行的主要变异体的SARS-CoV-2变异株（2021年5月至2021年11月的Delta和2021年12月至2022年3月的Omicron），疫苗接种和疫苗产品后的持续时间。
结果：我们招募了1145名有症状的HCWs。中位年龄为30岁（IQR：26-38），789（68.9％）为女性。二百八十二（24.6％）完全接种疫苗。完全接种疫苗的中位时间为102天(IQR:56-144)。对于完全接种疫苗的参与者，有症状的SARS-CoV-2感染的VE为72.7％（95％CI：61.9％至80.7％）。在Delta期间，VE为79.4％（95％CI：58.2％至90.7％），在Omicron期间为37.5％（95％CI：-7.0％至63.3％）。
结论：当Delta变异体循环时，COVID-19疫苗可有效减少赞比亚HCWs中有症状的SARS-CoV-2，但当Omicron循环时无效。这可能与免疫逃避特征和/或免疫力下降有关。这些发现支持加快使用二价疫苗的COVID-19加强剂量，作为疫苗接种计划的一部分，以减少赞比亚的COVID-19。
方法：我们从2021年5月至2022年3月，在赞比亚不同级别的医疗机构中，SARS-CoV-2疫苗的完整时间表在预防有症状的COVID-19方面的疫苗有效性如何？
方法：1767名参与者进入研究并完成研究。病例为实验室确诊的SARS-CoV-2的HCWs，对照组为SARS-CoV-2阴性的HCWs。这项研究包括了有COVID-19疫苗接种史的同意的HCWs(仅限接种疫苗的HCWs)。具有未知测试结果和未知疫苗接种状态的HCWs，被排除在外。
方法：主要结局是有症状的HCWs中的VE。次要结果是VE：基于在赞比亚流行的主要变异体的SARS-CoV-2变异株（2021年5月至2021年11月的Delta和2021年12月至2022年3月的Omicron），疫苗接种和疫苗产品后的持续时间。
结果：我们招募了1145名有症状的HCWs。中位年龄为30岁（IQR：26-38），789（68.9％）为女性。二百八十二（24.6％）完全接种疫苗。完全接种疫苗的中位时间为102天(IQR:56-144)。对于完全接种疫苗的参与者，有症状的SARS-CoV-2感染的VE为72.7％（95％CI：61.9％至80.7％）。在Delta期间，VE为79.4％（95％CI：58.2％至90.7％），在Omicron期间为37.5％（95％CI：-7.0％至63.3％）。
结论：当Delta变异体循环时，COVID-19疫苗可有效减少赞比亚HCWs中有症状的SARS-CoV-2，但当Omicron循环时无效。这可能与免疫逃避特征和/或免疫力下降有关。这些发现支持加快使用二价疫苗的COVID-19加强剂量，作为疫苗接种计划的一部分，以减少赞比亚的COVID-19。
