Reduced humoral response 3 months following BNT162b2 vaccination in SARS-CoV-2 uninfected residents of long-term care facilities
Macedonia Trigueros, Edwards Pradenas, Dolors Palacín, F Muñoz-López, Carlos Ávila‐Nieto, Benjamin Trinité, Josep Maria Bonet, Mar Isnard, Nemesio Moreno, Sílvia Marfil, Carla Rovirosa, Teresa Puig, Eulàlia Grau, Anna Chamorro, Ana Marı́a Salinas-Martı́nez, Ruth Toledo, Marta Font, Jordi Ara, Jorge Carrillo, Lourdes Mateu, Julià Blanco, Bonaventura Clotet, Núria Prat, Marta Massanella, on behalf of the CoronAVI@S and the KING cohort extension studies, Soto Carrión, N Salarich Solà, A Vidal, R Alvarez Viñallonga, Jesús Tornero, Ester Tio Vilamala, Cecilia Suárez, T Gonzalo, Lautaro G. Perez, D Sans, A Blancas Loras, A G Archer, Josep M. Borràs, S Cervelló, GLL Gemma Llados, Samuel España, José Ramón Santos, Cora Loste, Cristina López, Isabel González Casafont, Cristina Estany, C. Rodriguez, Jaime Moreno-Muñoz, Anna Prats, Cristina Herrero, Ana María Arnáiz García, Maritza Montero, P. Tornero, N Gonzalez Palomares, A Grajea, Luis Ortíz, C Miranda, Elena Abad, David J. Figueroa, Alex Mancera, S Gonzalez Alonso, Marco Pérez, Laura Esteban, M.C. Ortiz, Laia Valls, Luisa Fernanda Zúñiga Cerón, Talita Cristina Araújo Baena, Carlos Ruiz de Alegría Puig, M Cucurell, Jordi Puig
Abstract
BACKGROUND: SARS-CoV-2 vaccination is the most effective strategy to protect older residents of long-term care facilities (LTCF) against severe COVID-19, but primary vaccine responses are less effective in older adults. Here, we characterised the humoral responses of institutionalised seniors 3 months after they had received the mRNA/BNT162b2 vaccine. METHODS: plasma levels of SARS-CoV-2-specific total IgG, IgM and IgA antibodies were measured before and 3 months after vaccination in older residents of LTCF. Neutralisation capacity was assessed in a pseudovirus neutralisation assay against the original WH1 and later B.1.617.2/Delta variants. A group of younger adults was used as a reference group. RESULTS: three months after vaccination, uninfected older adults presented reduced SARS-CoV-2-specific IgG levels and a significantly lower neutralisation capacity against the WH1 and Delta variants compared with vaccinated uninfected younger individuals. In contrast, COVID-19-recovered older adults showed significantly higher SARS-CoV-2-specific IgG levels after vaccination than their younger counterparts, whereas showing similar neutralisation activity against the WH1 virus and an increased neutralisation capacity against the Delta variant. Although, similarly to younger individuals, previously infected older adults elicit potent cross-reactive immune responses, higher quantities of SARS-CoV-2-specific IgG antibodies are required to reach the same neutralisation levels. CONCLUSIONS: although hybrid immunity seems to be active in previously infected older adults 3 months after mRNA/BNT162b2 vaccination, humoral immune responses are diminished in COVID-19 uninfected but vaccinated older residents of LTCF. These results suggest that a vaccine booster dose should be prioritised for this particularly vulnerable population.