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. 2022 Jan 24;40(3):531-535.
doi: 10.1016/j.vaccine.2021.11.086. Epub 2021 Dec 3.

Humoral anti-SARS-CoV-2 immune response after two doses of Comirnaty vaccine in nursing home residents by previous infection status

François Helle  1 , Julien Moyet  2 , Baptiste Demey  1 , Catherine François  1 , Gilles Duverlie  1 , Sandrine Castelain  1 , Fréderic Bloch  2 , Etienne Brochot  3
Affiliations

Humoral anti-SARS-CoV-2 immune response after two doses of Comirnaty vaccine in nursing home residents by previous infection status

François Helle et al. Vaccine. .

Abstract

Background: Coronavirus disease 2019 (COVID-19) is associated with increased morbidity and mortality in older adults. Although the advent of the first vaccines has significantly reduced these rates, data on older adults in clinical trials are scarce.

Objectives: We quantified and compared the humoral response in individuals with vs. without pre-existing seropositivity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in a cohort of 69 patients living in a nursing home and who had received the recommended two doses of the Comirnaty (Pfizer-BioNTech®) vaccine.

Results: All 69 patients (100%) tested positive for antibodies against SARS-CoV-2 at 2 months post-vaccination. Residents with a pre-vaccination infection had significantly higher titers of anti-spike 1 IgG than those with no prior infection (median [interquartile range]: 55,726 [14463-78852] vs. 1314 [272-1249] arbitrary units, respectively; p < 0.001). The same result was observed for neutralizing antibodies titers (704 [320-1280] vs. 47 [20-40] respectively; p < 0.001). Between the pre-vaccination and post-vaccination periods, for IgG and neutralizing antibodies, we observed a 49 and 8-fold increase respectively. In comparison to the wild-type Receptor Binding Domain (RBD), the binding capacity of these vaccine sera was significantly decreased on the B.1.351 and P.1 variants RBD but not decreased with respect to the B.1.1.7 RBD. Although all nursing home residents developed a humoral response following Comirnaty vaccine, its intensity appeared to depend on the pre-vaccination serological status.

Conclusion: Our results raise the question of how many doses of vaccine should be administered in older and how long the protection will be effective.

Keywords: COVID-19; Humoral vaccine response; SARS-CoV-2; Serological assay.

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Conflict of interest statement

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Distribution of titers 2 months after vaccination for (A) anti-spike-1 IgG (in AU/mL) and (B) neutralizing antibodies among seronegative, seropositive for SARS-CoV-2 before vaccination and for non-vaccinated home nursing residents.
Fig. 2
Fig. 2
Scatter plot of titers for (A) anti-spike-1 IgG (in AU/mL) and (B) neutralizing antibodies in seropositive and seronegative groups 2 months after vaccination and in the control group. The solid lines correspond to the mean. The dashed line corresponds to the positivity cut-off of 50 AU/mL.
Fig. 3
Fig. 3
Titers for (A) anti-spike IgG and (B) neutralizing antibodies before and after vaccination in 46 nursing home residents with pre-existing immunity to SARS-CoV-2.
Fig. 4
Fig. 4
Scatter plot of 2 months post-vaccination samples binding titer on S1-RBD WT, S1-RBD B.1.1.7 (UK), S1-RBD B.1.351 (SA) and S1-RBD P.1 (BRA) among seronegative, seropositive for SARS-CoV-2 before vaccination and for non-vaccinated home nursing residents. The solid lines correspond to the mean.
See this image and copyright information in PMC

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