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

Objectives: 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.

Methods: Vaccine response was evaluated 1, 3 and 6 months after second dose of Pfizer-BioNTech COVID-19 Vaccine and 30 days after booster vaccination.