Evolution of antibody titers after two doses of mRNA Pfizer-BioNTech vaccine and effect of the third dose in nursing home residents

• Published in: PloS one Vol. 18; no. 3; p. e0282388
• Main Authors: Rodríguez-Avial, Iciar, García-Salguero, Cristina, Bermejo, Laura, Teja, Juan, Pérez-Cecilia, Elisa, Delgado-Iribarren, Alberto, Vigara, Marta, Gil, Pedro, Culebras, Esther
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08-03-2023; Public Library of Science (PLoS)
• Subjects: Age; Antibodies; Antibodies, Viral; Antibody response; Biology and life sciences; BNT162 Vaccine; Coronaviruses; COVID-19 - prevention & control; COVID-19 vaccines; Disease transmission; Evaluation; Evolution; Females; Health aspects; Hospitals; Humans; IgG antibody; Immune response; Immune system; Immunogenicity; Immunoglobulin G; Immunoglobulins; Infections; Informed consent; Lymphocytes T; Male; Medicine and Health Sciences; Messenger RNA; mRNA; Normal distribution; Nursing home patients; Nursing Homes; Older people; Pharmaceutical industry; Product development; Questionnaires; RNA, Messenger; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Vaccines; Values; Womens health; United States; Spain; Madrid Spain
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0282388

We evaluated the IgG antibody titer against SARS-CoV-2 in 196 residents of a Spanish nursing home after the second dose of the BNT162b2 vaccine and the evolution of this titer over time. The role of the third dose of the vaccine on immune-response is also analysed in 115 of participants.
Vaccine response was evaluated 1, 3 and 6 months after second dose of Pfizer-BioNTech COVID-19 Vaccine and 30 days after booster vaccination. Total anti-RBD (receptor binding domain) IgG immunoglobulins were measured to assess response. Six month after the second dose of vaccine and previously to the booster, T-cell response was also measured in 24 resident with different antibody levels. T-spot Discovery SARS-CoV-2 kit was used to identify cellular immunogenicity.
As high as 99% of residents demonstrated a positive serological response after second dose. Only two patients showed no serologic response, two men without records of previous SARS-CoV-2 infection. A higher immune response was associated with prior SARS-CoV-2 infection regardless of the gender or age. The anti-S IgG titers decreased significantly in almost all the participants (98.5%) after six months of vaccination whatever previous COVID-infection. The third dose of vaccine increased antibody titers in all patients, although initial vaccination values were not restored in the majority of cases.
The main conclusion of the study is that vaccine resulted in good immunogenicity in this vulnerable population. Nevertheless more data are needed on the long-term maintenance of antibody response after booster vaccination.