Optimizing COVID-19 vaccination for older adults: superior efficacy of heterologous regimens in reducing infection and mortality rates among patients aged 80 years and older during the Omicron BA.5/BF.7 outbreak.

Songlin Qiu, Yijun Chen, Awei Sheng, Bo Shen, Sailing He, Yufen Zheng

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Article in BMC infectious diseases, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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6 authors.

Songlin Qiu *Department of Clinical Laboratory, Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, 150 Ximen Road, Linhai, 317000, China.

Yijun Chen *Department of Clinical Laboratory, Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, 150 Ximen Road, Linhai, 317000, China.

Awei ShengDepartment of Clinical Laboratory, Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, 150 Ximen Road, Linhai, 317000, China.

Bo ShenDepartment of Clinical Laboratory, Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, 150 Ximen Road, Linhai, 317000, China. shenb@enzemed.com.

Sailing HeZhejiang Engineering Research Center for Intelligent Medical Imaging, Sensing and Non-invasive Rapid Testing, Taizhou Hospital, Zhejiang University, Taizhou, China. sailing@kth.se.

Yufen ZhengDepartment of Clinical Laboratory, Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, 150 Ximen Road, Linhai, 317000, China. zhengyf@enzemed.com.

Funding

National Key Research and Development Program of China 2022YFC2010003 and 2022YFC3601002"Pioneer" and "Leading Goose" R&D Program of Zhejiang Province 2023C03083

6 · The paper itself

Abstract

backgroundFollowing the adjustment of COVID-19 control policies in mainland China, particularly during the Omicron BA.5 and BF.7 waves, evaluating vaccine effectiveness in individuals aged ≥ 80 years is of critical importance. PATIENTS AND

methodsThis retrospective study included 2,325 hospitalized patients aged 80 years and older from four hospitals between December 9, 2022, and January 27, 2023. We assessed the associations of vaccination dose, vaccination regimen, and the interval since the last vaccination with SARS-CoV-2 infection and mortality. Univariable and multivariable logistic regression analyses were performed to adjust for baseline imbalances across vaccination groups. An exploratory NAb analysis was conducted in 138 patients with paired serum samples at admission and discharge to evaluate immune responses associated with different vaccination strategies.

resultsIn the unadjusted analyses, SARS-CoV-2 infection and mortality rates decreased with increasing vaccine doses. After adjustment for age, diabetes, and hyperlipidemia, receipt of 1, 2, and 3 vaccine doses was associated with lower odds of SARS-CoV-2 infection compared with no vaccination, with adjusted ORs of 0.644 (95% CI: 0.445-0.931, P = 0.019), 0.579 (95% CI: 0.407-0.823, P = 0.002), and 0.448 (95% CI: 0.332-0.607, P < 0.001), respectively. Three-dose vaccination was also associated with lower odds of mortality (OR = 0.563, 95% CI: 0.380-0.835, P = 0.004). In the regimen-based model, CoronaVac plus ZF2001 was associated with lower odds of infection (OR = 0.456, 95% CI: 0.235-0.885, P = 0.020) and mortality (OR = 0.410, 95% CI: 0.123-0.878, P = 0.047) after adjustment. In the exploratory NAb subgroup analysis, patients receiving CoronaVac plus ZF2001 showed higher NAb levels at both admission and discharge.

conclusionsDuring the Omicron BA.5/BF.7 wave, receipt of three COVID-19 vaccine doses was associated with lower risks of SARS-CoV-2 infection and mortality among hospitalized patients aged 80 years and older. The heterologous regimen of CoronaVac plus ZF2001 was associated with lower risks of infection and mortality and higher NAb levels. These findings support the potential value of optimized booster and heterologous vaccination strategies for improving COVID-19-related outcomes in this high-risk older population. CLINICAL TRIAL: N/A.

Indexed as

COVID-19COVID-19 VaccinesVaccinationVaccine EfficacyAged, 80 and overAntibodies, NeutralizingChinaDisease OutbreaksFemaleHumansMaleRetrospective StudiesSARS-CoV-2Antibodies, NeutralizingCOVID-19 VaccinesAged 80 years and olderCOVID-19EfficacyHeterologousVaccination

Identifiers

PMID42393578

DOI10.1186/s12879-026-13824-3

PMCPMC13602511

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.