Protection against COVID-19 hospitalisation conferred by primary-series vaccination with AZD1222 in non-boosted individuals: first vaccine effectiveness results of the European COVIDRIVE study and meta-regression analysis.

Abstract

Background:

Vaccine effectiveness (VE) studies with long-term follow-up are needed to understand durability of protection against severe COVID-19 outcomes conferred by primary-series vaccination in individuals not receiving boosters. COVIDRIVE is a European public-private partnership evaluating brand-specific vaccine effectiveness (VE). We report a prespecified interim analysis of primary-series AZD1222 (ChAdOx1 nCoV-19) VE.

Methods:

Seven Study Contributors in Europe collected data on individuals aged ≥18 years who were hospitalised with severe acute respiratory infection (June 1st, 2021-September 5th, 2022) and eligible for COVID-19 vaccination prior to hospitalisation. In this test-negative case-control study, individuals were defined as test-positive cases or test-negative controls (SARS-CoV-2 RT-PCR) and were either fully vaccinated (two AZD1222 doses, 4-12 weeks apart, completed ≥14 days prior to symptom onset; no booster doses) or unvaccinated (no COVID-19 vaccine prior to hospitalisation). The primary objective was to estimate AZD1222 VE against COVID-19 hospitalisation. A literature review and meta-regression were conducted to contextualise findings on durability of protection.

Findings:

761 individuals were included during the 15-month analysis period. Overall AZD1222 VE estimate was 72.8% (95% CI, 53.4-84.1). VE was 93.8% (48.6-99.3) in participants who received second AZD1222 doses ≤8 weeks prior to hospitalisation, with spline-based VE estimates demonstrating protection (VE ≥ 50%) 30 weeks post-second dose. Meta-regression analysis (data from seven publications) showed consistent results, with ≥80% protection against COVID-19 hospitalisation through ∼43 weeks post-second dose, with some degree of waning.

Interpretation:

Primary-series AZD1222 vaccination confers protection against COVID-19 hospitalisation with enduring levels of VE through ≥6 months.

Funding:

AstraZeneca.

• Authors: Wilhelmine Meeraus, Leonie de Munter, Christen M Gray, Akshat Dwivedi, Chloé Wyndham-Thomas, Mario Ouwens, Wendy Hartig-Merkel, Laura Drikite, Griet Rebry, Antonio Carmona, Anke L Stuurman, Thi Yen Chi Nguyen, Guillermo Mena, Ainara Mira-Iglesias, Giancarlo Icardi, Susana Otero-Romero, Sebastian Baumgartner, Charlotte Martin, Sylvia Taylor, Kaatje Bollaerts
• Journal: The Lancet regional health. Europe (Lancet Reg Health Eur) Vol. 31 Pg. 100675 (Aug 2023) ISSN: 2666-7762 [Electronic] England
• PMID: 37547274 (Publication Type: Journal Article)
• Copyright: © 2023 The Author(s).