Severe Acute Respiratory Syndrome Coronavirus 2 Adaptive Immunity in Nursing Home Residents Following a Third Dose of the Comirnaty Coronavirus Disease 2019 Vaccine

Giménez

et al. 2022

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Studies investigating the cumulative incidence of and immune status against SARS‐CoV‐2 infection provide valuable information for shaping public health decision‐making. A cross‐sectional study on 935 participants, conducted in the Valencian Community (VC), measuring anti‐SARS‐CoV‐2‐receptor binding domain‐RBD‐total antibodies and anti‐Nucleocapsid (N)‐IgGs via electrochemiluminescence assays. Quantitation of neutralizing antibodies (NtAb) against ancestral and Omicron BA.1 and BA.2 variants and enumeration of SARS‐CoV‐2‐S specific‐IFNγ‐producing CD4+ and CD8+ T cells was performed in 100 and 137 participants, respectively. The weighted cumulative incidence was 51.9% (95% confidence interval [CI]: 48.7–55.1) and was inversely related to age. Anti‐RBD total antibodies were detected in 97% of participants; vaccinated and SARS‐CoV‐2‐experienced (VAC‐ex; n = 442) presented higher levels (p < 0.001) than vaccinated/naïve (VAC‐n; n = 472) and nonvaccinated/experienced (UNVAC‐ex; n = 63) subjects. Antibody levels correlated inversely with time elapsed since last vaccine dose in VAC‐n (Rho, −0.52; p < 0.001) but not in VAC‐ex (rho −0.02; p = 0.57). Heterologous booster shots resulted in increased anti‐RBD antibody levels compared with homologous schedules in VAC‐n, but not in VAC‐ex. NtAbs against Omicron BA.1 were detected in 94%, 75%, and 50% of VAC‐ex, VAC‐n and UNVAC‐ex groups, respectively. For Omicron BA.2, the figures were 97%, 84%, and 40%, respectively. SARS‐CoV‐2‐S‐reactive IFN‐γ T cells were detected in 73%, 75%, and 64% of VAC‐ex, VAC‐n and UNVAC‐ex, respectively. Median frequencies for both T‐cell subsets were comparable across groups. In summary, by April 2022, around half of the VC population had been infected with SARS‐CoV‐2 and, due to extensive vaccination, displayed hybrid immunity.

Section: Methodsmentioning

confidence: 99%

Cumulative incidence of SARS‐CoV‐2 infection in the general population of the Valencian Community (Spain) after the surge of the Omicron BA.1 variant

Giménez

et al. 2022

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“…NtAb targeting the S protein were measured using a Green Fluorescent protein‐expressing vesicular stomatitis virus pseudotyped with the Wuhan‐Hu‐1 variant, and Omicron BA.1 and BA.2 sublineages, following a previously published protocol, 23 , 24 with several modifications (Supporting Information material). Sera resulting in less than 50% neutralization at the lowest dilution tested were arbitrarily ascribed a reciprocal antibody titer of 10 (the limit of detection of the assay).…”

Section: Methodsmentioning

confidence: 99%

A performance comparison of two (electro) chemiluminescence immunoassays for detection and quantitation of serum anti‐spike antibodies according to SARS‐CoV‐2 vaccination and infections status

Zulaica

et al. 2022

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The information provided by SARS‐CoV‐2 spike (S)‐targeting immunoassays can be instrumental in clinical‐decision making. We compared the performance of the Elecsys® Anti‐SARS‐CoV‐2 S assay (Roche Diagnostics) and the LIAISON® SARS‐CoV‐2 TrimericS IgG assay (DiaSorin) using a total of 1176 sera from 797 individuals, of which 286 were from vaccinated‐SARS‐CoV‐2/experienced (Vac‐Ex), 581 from vaccinated/naïve (Vac‐N), 147 from unvaccinated/experienced (Unvac‐Ex), and 162 from unvaccinated/naïve (Unvac‐N) individuals. The Roche assay returned a higher number of positive results (907 vs. 790; p = 0.45; overall sensitivity: 89.3% vs. 77.6%). The concordance between results provided by the two immunoassays was higher for sera from Vac‐N (ϰ: 0.58; interquartile ranges [IQR]: 0.50−0.65) than for sera from Vac‐Ex (ϰ: 0.19; IQR: −0.14 to 0.52) or Unvac‐Ex (ϰ: 0.18; IQR: 0.06−0.30). Discordant results occurred more frequently among sera from Unvac‐Ex (34.7%) followed by Vac‐N (14.6%) and Vac‐Ex (2.7%). Antibody levels quantified by both immunoassays were not significantly different when <250 (p = 0.87) or <1000 BAU/ml (p = 0.13); in contrast, for sera ≥1000 BAU/ml, the Roche assay returned significantly higher values than the DiaSorin assay (p < 0.008). Neutralizing antibody titers (NtAb) were measured in 127 sera from Vac‐Ex or Vac‐N using a S‐pseudotyped virus neutralization assay of Wuhan‐Hu‐1, Omicron BA.1, and Omicron BA.2. The correlation between antibody levels and NtAb titers was higher for sera from Vac‐N than those from Vac‐Ex, irrespective of the (sub)variant considered. In conclusion, neither qualitative nor quantitative results returned by both immunoassays are interchangeable. The performance of both assays was found to be greatly influenced by the vaccination and SARS‐CoV‐2 infection status of individuals.

“…17 NtAbs against Omicron BA.2 and BA4/5 were measured using a GFP-expressing vesicular stomatitis virus pseudotyped with the Omicron BA.2 and BA.4/5 S protein, as described elsewhere. [18][19][20]…”

Section: Antibody Assaysmentioning

confidence: 99%

A machine learning model for predicting serum neutralizing activity against Omicron SARS‐CoV‐2 BA.2 and BA.4/5 sublineages in the general population

Álvarez‐Rodríguez

et al. 2023

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Supervised machine learning (ML) methods have been used to predict antibody responses elicited by COVID-19 vaccines in a variety of clinical settings. Here, we explored the reliability of a ML approach to predict the presence of detectable neutralizing antibody responses (NtAb) against Omicron BA.2 and BA.4/5 sublineages in the general population. Anti-SARS-CoV-2 receptor-binding domain (RBD) total antibodies were measured by the Elecsys ® Anti-SARS-CoV-2 S assay (Roche Diagnostics) in all participants. NtAbs against Omicron BA.2 and BA4/5 were measured using a SARS-CoV-2 S pseudotyped neutralization assay in 100 randomly selected sera. A ML model was built using the variables of age, vaccination (number of doses) and SARS-CoV-2 infection status. The model was trained in a cohort (TC) comprising 931 participants and validated in an external cohort (VC) including 787 individuals. Receiver operating characteristics analysis indicated that an anti-SARS-CoV-2 RBD total antibody threshold of 2300 BAU/mL best discriminated between participants either exhibiting or not detectable Omicron BA.2 and Omicron BA.4/5-Spike targeted NtAb responses (87% and 84% precision, respectively). The ML model correctly classified 88% (793/901) of participants in the TC: 717/749 (95.7%) of those displaying ≥2300 BAU/mL and 76/152 (50%) of those exhibiting antibody levels <2300 BAU/mL. The model performed better in vaccinated participants, either with or without prior SARS-CoV-2 infection. The overall accuracy of the ML model in the VC was comparable. Our ML model, based upon a few easily collected parameters for predicting neutralizing activity against Omicron BA.2 and BA.4/5 (sub)variants circumvents the need to perform not only neutralization assays, but also anti-S serological tests, thus potentially saving costs in the setting of large seroprevalence studies.