AZD1222 effectiveness against severe COVID-19 in individuals with comorbidity or frailty: the RAVEN cohort study.

Publication date: Feb 29, 2024

Despite being prioritized during initial COVID-19 vaccine rollout, vulnerable individuals at high risk of severe COVID-19 (hospitalization, intensive care unit admission, or death) remain underrepresented in vaccine effectiveness (VE) studies. The RAVEN cohort study (NCT05047822) assessed AZD1222 (ChAdOx1 nCov-19) two-dose primary series VE in vulnerable populations. Using the Oxford-Royal College of General Practitioners Clinical Informatics Digital Hub, linked to secondary care, death registration, and COVID-19 datasets in England, COVID-19 outcomes in 2021 were compared in vaccinated and unvaccinated individuals matched on age, sex, region, and multimorbidity. Over 4. 5 million AZD1222 recipients were matched (mean follow-up ~5 months); 68% were ≥50 years, 57% had high multimorbidity. Overall, high VE against severe COVID-19 was demonstrated, with lower VE observed in vulnerable populations. VE against hospitalization was higher in the lowest multimorbidity quartile (91. 1%; 95% CI: 90. 1, 92. 0) than the highest quartile (80. 4%; 79. 7, 81. 1), and among individuals ≥65 years, higher in the ‘fit’ (86. 2%; 84. 5, 87. 6) than the frailest (71. 8%; 69. 3, 74. 2). VE against hospitalization was lowest in immunosuppressed individuals (64. 6%; 60. 7, 68. 1). Based on integrated and comprehensive UK health data, overall population-level VE with AZD1222 was high. VEs were notably lower in vulnerable groups, particularly the immunosuppressed.

Concepts Keywords
Frailest ChAdOx1 nCoV-19
Nct05047822 COVID-19
Oxford COVID-19 vaccines
Raven SARS-CoV-2


Type Source Name
disease VO effectiveness
disease MESH COVID-19
disease MESH comorbidity
disease VO COVID-19 vaccine
disease MESH death
disease VO vaccine effectiveness
disease VO dose
drug DRUGBANK Huperzine B
disease VO vaccinated
disease VO unvaccinated
disease VO population

Original Article

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