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. 2022;26(1):57-63.
doi: 10.1007/s12603-021-1713-4.

Kinetics of SARS-CoV-2-Neutralising Antibodies of Residents of Long-Term Care Facilities

J Moyet  1 , F Helle, G Bourdenet, C Joseph, B Gubler, G Deschasse, I Defouilloy, T Slovenski, C François, S Liabeuf, J L Schmit, J P Lanoix, S Castelain, F Bloch, E Brochot
Affiliations

Kinetics of SARS-CoV-2-Neutralising Antibodies of Residents of Long-Term Care Facilities

J Moyet et al. J Nutr Health Aging. 2022.

Abstract

Introduction: Elderly residents of nursing homes (NHs) and long-term care units (LTCUs) have been shown to have a high risk of mortality and morbidity in cases of SARS-CoV-2 infection. The objective of this study was to examine the kinetics of neutralizing antibodies (NAbs) directed against the SARS-CoV-2 virus in residents of the NH and LTCU units of our University Hospital who were identified with positive serology after the first epidemic outbreak.

Materials and methods: The participants included were sampled every three months for qualitative serological testing, as well as quantitative testing by neutralization tests using retroviral particles containing the S glycoprotein of SARS-CoV-2. Vaccination using the Comirnaty (Pfizer BNT162b2) vaccine begun before the last serological follow-up.

Results: The median NAb titer in June 2020 was 80 [40; 60] versus 40 [40; 160] three months later, showing a statistically significant decline (p < 0.007), but remained stable between the three- and six-month timepoints (p = 0.867). By nine months after vaccination, we observed a significant difference between vaccinated residents known to have positive serology before vaccination (SERO+, Vacc+) and those vaccinated without having previously shown COVID-19 seroconversion (SERO-, Vacc+), the latter group showing similar titers to the SERO+, Vacc- participants (p=0.166). The median antibody titer in SERO+, Vacc+ patients increased 15-fold following vaccination.

Discussion: Humoral immunity against SARS-CoV-2 appears to be persistent in elderly institutionalized patients, with a good post-vaccination response by residents who had already shown seroconversion but a notably diminished response by those who were seronegative before vaccination. To evaluate immunity in its entirety and elaborate a sound vaccination strategy, the cellular immune response via T cells specific to SARS-CoV-2 merits analysis, as this response is susceptible to being affected by immunosenescence.

Keywords: COVID-19; SARS-CoV-2; immunosenescence; nursing homes; serological assay.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Evolution of COVID-19 seroprevalence in the NHs and LTCUs
Figure 2
Figure 2
Neutralising antibody (NAb) titers in positive patients at the moment of the June screening campaign and their evolution (A) Box plot showing the evolution of median NAb titers over six months, with medians and IQRs and minimal and maximal values at the extremities. (B-D) Distribution of titers (%) in June (B), at M3 (C), and at M6 (D).
Figure 3
Figure 3
Neutralising antibody (Nab) titers and their repartition after vaccination (A) Box plot with the median NAb titers and IQRs and minimal and maximal values at the extremities for the SERO+, Vacc−; SERO+, Vacc+; and SERO-, Vacc+ groups. (B-D) Distribution, in percentages, of NAb titers in the (B) SERO+, Vacc-; (C) SERO+, Vacc+; and (D) SERO−, Vacc+ groups.
Figure 4
Figure 4
Evolution of neutralizing antibody (Nab) titers (medians and IQs and minimal and maximal values at the extremities) between M6 and M9 for residents who received two Comirnaty (Pfizer BNT162b2) vaccine doses
See this image and copyright information in PMC

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