Person: Vial Cox, María Cecilia
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Vial Cox
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María Cecilia
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María Cecilia Vial Cox
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Publication A Third Dose of SARS-CoV-2 mRNA Vaccine Improves Immune Response in Chronic Kidney Disease Patients(2023) Poli Harlowe, María Cecilia; Vial Cox, María Cecilia; Rey, Emma; González, Natalia; Cortés, Lina; Hormazabal, Juan; Ramírez, Carolina; De la Cruz, Javiera; Ulloa, CamiloChronic kidney disease (CKD) patients have an increased risk of morbidity and mortality following SARS-CoV-2 infection. Vaccination in these patients is prioritized, and monitoring of the immune response is paramount to define further vaccination strategies. This prospective study included a cohort of 100 adult CKD patients: 48 with kidney transplant (KT) and 52 on hemodialysis without prior COVID-19. The patients were assessed for humoral and cellular immune responses after four months of an anti-SARS-CoV-2 primary two-dose vaccination scheme (CoronaVac or BNT162b2) and one month after a booster third dose of BNT162b2 vaccine. We identified poor cellular and humoral immune responses in the CKD patients after a primary vaccination scheme, and these responses were improved by a booster. Robust polyfunctional CD4+ T cell responses were observed in the KT patients after a booster, and this could be attributed to a higher proportion of the patients having been vaccinated with homologous BNT162b2 schemes. However, even after the booster, the KT patients exhibited lower neutralizing antibodies, attributable to specific immunosuppressive treatments. Four patients suffered severe COVID-19 despite three-dose vaccination, and all had low polyfunctional T-cell responses, underscoring the importance of this functional subset in viral protection. In conclusion, a booster dose of SARS-CoV-2 mRNA vaccine in CKD patients improves the impaired humoral and cellular immune responses observed after a primary vaccination scheme.Publication 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(2023) Hormazabal, Juan; Nuñez-Franz, Loreto; Rubilar, Paola; Apablaza, Mauricio; Vial Cox, María Cecilia; Cortes Salinas, Lina Jimena; González, Natalia; Vial, Pablo; Said, Macarena; Gonzalez Wiedmaier, Claudia; Olivares, Kathya; Aguilera, Ximena; Ramírez-Santana, MurielThe 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.