Weak humoral immune reactivity among residents of long-term care facilities following one dose of the BNT162b2 mRNA COVID-19 vaccine

Abstract

Background. Several Canadian provinces are extending the interval between COVID-19 vaccine doses to increase population vaccine coverage more rapidly. However, immunogenicity of these vaccines after one dose is incompletely characterized, particularly among the elderly, who are at greatest risk of severe COVID-19. Methods. We assessed SARS-CoV-2 humoral responses pre-vaccine and one month following the first dose of BNT162b2 mRNA vaccine, in 12 COVID-19 seronegative residents of long-term care facilities (median age, 82 years), 18 seronegative healthcare workers (HCW; median age, 36 years) and 4 convalescent HCW. Total antibody responses to SARS-CoV-2 nucleocapsid (N) and spike protein receptor binding domain (S/RBD) were assessed using commercial immunoassays. We quantified IgG and IgM responses to S/RBD and determined the ability of antibodies to block S/RBD binding to ACE2 receptor using ELISA. Neutralizing antibody activity was also assessed using pseudovirus and live SARS-CoV-2. Results. After one vaccine dose, binding antibodies against S/RBD were ~4-fold lower in residents compared to HCW (p<0.001). Inhibition of ACE2 binding was 3-fold lower in residents compared to HCW (p=0.01) and pseudovirus neutralizing activity was 2-fold lower (p=0.003). While six (33%) seronegative HCW neutralized live SARS-CoV-2, only one (8%) resident did (p=0.19). In contrast, convalescent HCW displayed 7- to 20-fold higher levels of binding antibodies and substantial ability to neutralize live virus after one dose. Interpretation. Extending the interval between COVID-19 vaccine doses may pose a risk to the elderly due to lower vaccine immunogenicity in this group. We recommend that second doses not be delayed in elderly individuals.

Humoral and Cellular Immune Responses Against Severe Acute Respiratory Syndrome Coronavirus 2 Variants and Human Coronaviruses After Single BNT162b2 Vaccination

“…In summary, our data demonstrate suboptimal neutralizing antibody activity against SARS-CoV-2 WT and VOC after a single BNT162b2 vaccination, consistent with previous studies [ 25 , 36 ]. T cells, which responded equally to spike-derived peptides from SARS-CoV-2 WT, B.1.1.7, and B.1.351, were detectable with a broad interindividual range and influenced by cross-reactive T cells against hCoVs.…”

“…We propose that nonneutralizing antibody function and/or cellular immunity constitutes an important outcome after vaccination and may be part of the early defense against SARS-CoV-2 infection. We conclude that studies confidently assessing COVID-19 protection and sterile immunity against SARS-CoV-2 have yet to be completed; until then, variations in effective immunization programs cannot be confidently recommended [ 36 , 38 ].…”

Immune Assessment of BNT162b2 m-RNA-Spike Based Vaccine Response in Adults

“…The patients under hemodialysis treatment have impaired immune systems [ 23 ], and a reduction in their humoral response after the BNT162b2 vaccine compared with controls has been observed [ 24 ]. Moreover, residents of long-term care facilities developed a weak humoral response after one dose of BNT162b2 [ 25 ]. However, up until now, there is a lack of data about the cellular immune response induced after vaccination in these groups of immunosuppressed patients.…”

B- and T-cell immune responses elicited by the Comirnaty® COVID-19 vaccine in nursing-home residents

“…Real-world data have confirmed the efficacy of the vaccine in protecting against the occurrence of severe clinical forms of the disease [6,7]. Nevertheless, information on the immunogenicity and efficacy of this vaccine in elderly people with comorbidities and frailty is scarce [8,9]; such people have been prioritized for vaccination worldwide due to their increased risk of developing severe clinical forms of COVID-19 [10]. To gain further insight into this issue, we assess here SARS-CoV-2-Stargeted antibody and functional T-cell responses after vaccination with Comirnaty in a cohort of nursing-home residents, most displaying one or more comorbidities, and either presumably SARS-CoV-2-naïve or with documented prior SARS-CoV-2 infection.…”