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Hormazábal J, Nuñez-Franz L, Rubilar P, Apablaza M, Vial C, Cortés LJ, González N, Vial P, Said M, González C, Olivares K, Aguilera X, Ramírez-Santana M. Factors influencing neutralizing antibody response to the original SARS-CoV-2 virus and the Omicron variant in a high vaccination coverage country, a population-based study. Vaccine X 2023; 15:100372. [PMID: 37693843 PMCID: PMC10492202 DOI: 10.1016/j.jvacx.2023.100372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/27/2023] [Accepted: 08/14/2023] [Indexed: 09/12/2023] Open
Abstract
The study compared immunity to the original SARS-CoV-2 virus (Wuhan) and the Omicron variant using neutralizing antibodies (NAbs), that provide a good approximation of protective immunity. The results might help determine immunization strategies. DESIGN AND METHODS Unlike previous studies, we analyzed NAbs in a random sample of 110 IgG positive sera from individuals who participated in a population-based seroprevalence transversal study, carried out in May 2022 in two Chilean cities, a country with high vaccination coverage. RESULTS Our findings indicate that 98.2% of individuals had NAbs against Wuhan, 65.5% against Omicron, and 32.7% tested positive for Wuhan but not Omicron. Factors influencing protective immunity included a prior natural infection and the number of vaccines received. NAbs titers against the original virus were high, demonstrating vaccine effectiveness in the population. However, the level of antibodies decreased when measuring NAbs against Omicron, particularly among older individuals, indicating a decline in vaccine protection. Previous COVID-19 episodes acted as a natural booster, increasing NAbs titers against both virus strains. CONCLUSIONS Protective immunity against the original Wuhan SARS-CoV-2 virus is reduced when compared to Omicron variant. Updating vaccine to target emerging variants and continued monitoring of effectiveness at the population level are necessary.
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Affiliation(s)
- Juan Hormazábal
- Instituto de Ciencias e Innovación en Medicina, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Loreto Nuñez-Franz
- Departamento de Salud Pública, Facultad de Ciencias de la Salud, Universidad de Talca, Talca, Chile
| | - Paola Rubilar
- Centro de Epidemiología y Políticas de Salud, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | | | - Cecilia Vial
- Instituto de Ciencias e Innovación en Medicina, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Lina Jimena Cortés
- Instituto de Ciencias e Innovación en Medicina, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Natalia González
- Instituto de Ciencias e Innovación en Medicina, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Pablo Vial
- Instituto de Ciencias e Innovación en Medicina, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Macarena Said
- Departamento de Salud Pública, Facultad de Ciencias de la Salud, Universidad de Talca, Talca, Chile
| | - Claudia González
- Centro de Epidemiología y Políticas de Salud, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Kathya Olivares
- Departamento de Salud Pública, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
| | - Ximena Aguilera
- Centro de Epidemiología y Políticas de Salud, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Muriel Ramírez-Santana
- Departamento de Salud Pública, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
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