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. 2022 Jun;77(6):1885-1894.
doi: 10.1111/all.15142. Epub 2021 Oct 29.

Receptor binding domain-IgG levels correlate with protection in residents facing SARS-CoV-2 B.1.1.7 outbreaks

Hubert Blain  1 , Edouard Tuaillon  2 , Lucie Gamon  3 , Amandine Pisoni  2 , Stéphanie Miot  1 , Valentin Delpui  1 , Nejm Si-Mohamed  1 , Clémence Niel  2 , Yves Rolland  4 , Brigitte Montes  2 , Soraya Groc  2 , Sophia Rafasse  5   6 , Anne-Marie Dupuy  7 , Nathalie Gros  5   6 , Delphine Muriaux  5   6 , Marie-Christine Picot  3 , Jean Bousquet  8   9
Affiliations

Receptor binding domain-IgG levels correlate with protection in residents facing SARS-CoV-2 B.1.1.7 outbreaks

Hubert Blain et al. Allergy. 2022 Jun.

Abstract

Background: Limited information exists on nursing home (NH) residents regarding BNT162b2 vaccine efficacy in preventing SARS-CoV-2 and severe COVID-19, and its association with post-vaccine humoral response.

Methods: 396 residents from seven NHs suffering a SARS-CoV-2 B.1.1.7 (VOC-α) outbreak at least 14 days after a vaccine campaign were repeatedly tested using SARS-CoV-2 real-time reverse-transcriptase polymerase chain reaction on nasopharyngeal swab test (RT-qPCR). SARS-CoV-2 receptor-binding domain (RBD) of the S1 subunit (RBD-IgG) was measured in all residents. Nucleocapsid antigenemia (N-Ag) was measured in RT-qPCR-positive residents and serum neutralizing antibodies in vaccinated residents from one NH.

Results: The incidence of positive RT-qPCR was lower in residents vaccinated by two doses (72/317; 22.7%) vs one dose (10/31; 32.3%) or non-vaccinated residents (21/48; 43.7%; p < .01). COVID-19-induced deaths were observed in 5 of the 48 non-vaccinated residents (10.4%), in 2 of the 31 who had received one dose (6.4%), and in 3 of the 317 (0.9%) who had received two doses (p = .0007). Severe symptoms were more common in infected non-vaccinated residents (10/21; 47.6%) than in infected vaccinated residents (15/72; 21.0%; p = .002). Higher levels of RBD-IgG (n = 325) were associated with a lower SARS-CoV-2 incidence. No in vitro serum neutralization activity was found for RBD-IgG levels below 1050 AU/ml. RBD-IgG levels were inversely associated with N-Ag levels, found as a risk factor of severe COVID-19.

Conclusions: Two BNT162b2 doses are associated with a 48% reduction of SARS-CoV-2 incidence and a 91.3% reduction of death risk in residents from NHs facing a VOC-α outbreak. Post-vaccine RBD-IgG levels correlate with BNT162b2 protection against SARS-CoV-2 B.1.1.7.

Keywords: BNT162b2 vaccine; COVID-19; SARS-CoV-2; antibody response; efficacy; neutralizing antibodies; nucleocapsid antigenemia; nursing homes; residents; symptoms.

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Conflict of interest statement

The authors declare no conflicts of interest/competing interests.

Figures

FIGURE 1
FIGURE 1
Flow Diagram of the sample of residents having faced a COVID‐19 outbreak at least 14 days after a BNT162b2 vaccination campaign
FIGURE 2
FIGURE 2
SARS‐CoV‐2‐specific neutralizing antibody levels against SARS‐CoV‐2 wild type (WT) and VOC‐alpha depending on RBD‐IgG levels in 36 residents. Micro‐neutralization titers are expressed as the serial dilution for which 50% neutralization is measured
See this image and copyright information in PMC

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