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Cellular and Humoral Immune Responses and Breakthrough Infections After Two Doses of BNT162b Vaccine in Healthcare Workers (HW) 180 Days After the Second Vaccine Dose.
Mangia, Alessandra; Serra, Nicola; Cocomazzi, Giovanna; Giambra, Vincenzo; Antinucci, Stefano; Maiorana, Alberto; Giuliani, Francesco; Montomoli, Emanuele; Cantaloni, Paolo; Manenti, Alessandro; Piazzolla, Valeria.
  • Mangia A; Liver Unit, Fondazione IRCCS "Casa Sollievo della Sofferenza", San Giovanni Rotondo, Italy.
  • Serra N; Department of Public Health, University "Federico II", Naples, Italy.
  • Cocomazzi G; Liver Unit, Fondazione IRCCS "Casa Sollievo della Sofferenza", San Giovanni Rotondo, Italy.
  • Giambra V; Institute for Stem Cell Biology, Regenerative Medicine and Innovative Therapies (ISBReMIT), San Giovanni Rotondo, Italy.
  • Antinucci S; Allergy Diagnostic Section Euroimmun, Italy Fondazione "Casa Sollievo della Sofferenza", San Giovanni Rotondo, Italy.
  • Maiorana A; GSSL Unit, Fondazione "Casa Sollievo della Sofferenza", San Giovanni Rotondo, Italy.
  • Giuliani F; ICT Innovation and Research Unit, Fondazione IRCCS "Casa Sollievo della Sofferenza", San Giovanni Rotondo, Italy.
  • Montomoli E; Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.
  • Cantaloni P; VisMederi Srl, Siena, Italy.
  • Manenti A; VisMederi Srl, Siena, Italy.
  • Piazzolla V; VisMederi Srl, Siena, Italy.
Front Public Health ; 10: 847384, 2022.
Article in English | MEDLINE | ID: covidwho-1792872
ABSTRACT

Background:

Immunity and clinical protection induced by mRNA vaccines against SARS-CoV-2 have been shown to decline overtime. To gather information on the immunity profile deemed sufficient in protecting against hospitalization, we tested IgG levels, interferon-gamma (IFN-γ) secretion, and neutralizing antibodies 180 days (d180) after the second shot of BNT162b vaccine, in HW.

Methods:

A total of 392 subjects were enrolled. All received BioNTech/Pfizer from February 2020 to April 2021. The vaccine-specific humoral response was quantitatively determined by testing for IgG anti-S1 domain of SARS-CoV-spike protein. Live virus microneutralization (MN) was evaluated by an assay performing incubation of serial 2-fold dilution of human serum samples, starting from 110 to 15120, with an equal volume of Wuhan strain and Delta VOC viral solution and assessing the presence/absence of a cytopathic effect. SARS-CoV-2-spike protein-specific T-cell response was determined by a commercial IFN-γ release assay.

Results:

In 352 individuals, at d180, IgG levels decreased substantially but no results below the assay's positivity threshold were observed. Overall, 22 naive (8.1%) had values above the highest threshold. Among COVID-naive, the impact of age, which was observed at earlier stages, disappeared at d180, while it remained significant for 81 who had experienced a previous infection. Following the predictive model of protection by Khoury, we transformed the neutralizing titers in IU/ml and used a 54 IU/ml threshold to identify subjects with 50% protective immunity. Overall, live virus MN showed almost all subjects with previous exposure to SARS-CoV-2 neutralized the virus as compared to 33% of naive double-dosed subjects (p < 0.0001). All previously exposed subjects had strong IFN-γ secretion (>200 mIU/ml); among 271 naive, 7 (2.58%) and 17 (6.27%) subjects did not show borderline or strong secretion, respectively.

Conclusions:

In naive subjects, low IgG titers are relatively long-lasting. Only a third of naive subjects maintain neutralizing responses. After specific stimulation, a very limited number of naive were unable to produce IFN-γ. The results attained in the small group of subjects with breakthrough infection suggest that simultaneous neutralizing antibody titers <20, binding antibody levels/ml <200, and IFN-γ <1,000 mIU/ml in subjects older than 58 may identify at-risk groups.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: COVID-19 Vaccines / COVID-19 Type of study: Experimental Studies / Prognostic study / Randomized controlled trials Topics: Vaccines / Variants Limits: Humans Language: English Journal: Front Public Health Year: 2022 Document Type: Article Affiliation country: Fpubh.2022.847384

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Full text: Available Collection: International databases Database: MEDLINE Main subject: COVID-19 Vaccines / COVID-19 Type of study: Experimental Studies / Prognostic study / Randomized controlled trials Topics: Vaccines / Variants Limits: Humans Language: English Journal: Front Public Health Year: 2022 Document Type: Article Affiliation country: Fpubh.2022.847384