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Neutralizing antibody titers six months after Comirnaty vaccination: kinetics and comparison with SARS-CoV-2 immunoassays.
Padoan, Andrea; Cosma, Chiara; Bonfante, Francesco; Della Rocca, Foscarina; Barbaro, Francesco; Santarossa, Claudia; Dall'Olmo, Luigi; Pagliari, Matteo; Bortolami, Alessio; Cattelan, Annamaria; Cianci, Vito; Basso, Daniela; Plebani, Mario.
  • Padoan A; Department of Medicine-DIMED, University of Padova, Padova, Italy.
  • Cosma C; Department of Laboratory Medicine, University-Hospital of Padova, Padova, Italy.
  • Bonfante F; Department of Laboratory Medicine, University-Hospital of Padova, Padova, Italy.
  • Della Rocca F; Laboratory of Experimental Animal Models, Division of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy.
  • Barbaro F; Emergency Department, Padua University Hospital, Padova, Italy.
  • Santarossa C; Infective and Tropical Disease Unit, Padua University Hospital, Padova, Italy.
  • Dall'Olmo L; Emergency Department, Padua University Hospital, Padova, Italy.
  • Pagliari M; Department of Surgical Oncological and Gastroenterological Sciences - DISCOG, University of Padova, Padova, Italy.
  • Bortolami A; Veneto Institute of Oncology, IOV-IRCCS, Padova, Italy.
  • Cattelan A; Laboratory of Experimental Animal Models, Division of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy.
  • Cianci V; Laboratory of Experimental Animal Models, Division of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy.
  • Basso D; Infective and Tropical Disease Unit, Padua University Hospital, Padova, Italy.
  • Plebani M; Emergency Department, Padua University Hospital, Padova, Italy.
Clin Chem Lab Med ; 60(3): 456-463, 2022 02 23.
Article in English | MEDLINE | ID: covidwho-1575220
ABSTRACT

OBJECTIVES:

mRNA vaccines, including Comirnaty (BNT162b2 mRNA, BioNTech-Pfizer), elicit high IgG and neutralizing antibody (NAb) responses after the second dose, but the progressive decrease in serum antibodies against SARS-CoV-2 following vaccination have raised questions concerning long-term immunity, decreased antibody levels being associated with breakthrough infections after vaccination, prompting the consideration of booster doses.

METHODS:

A total number of 189 Padua University-Hospital healthcare workers (HCW) who had received a second vaccine dose were asked to collect serum samples for determining Ab at 12 (t12) and 28 (t28) days, and 6 months (t6m) after their first Comirnaty/BNT162b2 inoculation. Ab titers were measured with plaque reduction neutralization test (PRNT), and three chemiluminescent immunoassays, targeting the receptor binding domain (RBD), the trimeric Spike protein (trimeric-S), and surrogate viral neutralization tests (sVNT).

RESULTS:

The median percentages (interquartile range) for decrease in antibodies values 6 months after the first dose were 86.8% (67.1-92.8%) for S-RBD IgG, 82% (58.6-89.3%) for trimeric-S, 70.4% (34.5-86.4%) for VNT-Nab, 75% (50-87.5%) for PRNT50 and 75% (50-93.7%) for PRNT90. At 6 months, neither PRNT titers nor VNT-Nab and S-RBD IgG bAb levels correlated with age (p=0.078) or gender (p=0.938), while they were correlated with previous infection (p<0.001).

CONCLUSIONS:

After 6 months, a method-independent reduction of around 90% in anti-SARS-CoV-2 antibodies was detected, while no significant differences were found between values of males and females aged between 24 and 65 years without compromised health status. Further efforts to improve analytical harmonization and standardization are needed.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Antibodies, Neutralizing / COVID-19 Vaccines / SARS-CoV-2 / COVID-19 / Antibodies, Viral Topics: Vaccines Limits: Adult / Aged / Female / Humans / Male / Middle aged / Young adult Language: English Journal: Clin Chem Lab Med Journal subject: Chemistry, Clinical / Laboratory Techniques and procedures Year: 2022 Document Type: Article Affiliation country: Cclm-2021-1247

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Antibodies, Neutralizing / COVID-19 Vaccines / SARS-CoV-2 / COVID-19 / Antibodies, Viral Topics: Vaccines Limits: Adult / Aged / Female / Humans / Male / Middle aged / Young adult Language: English Journal: Clin Chem Lab Med Journal subject: Chemistry, Clinical / Laboratory Techniques and procedures Year: 2022 Document Type: Article Affiliation country: Cclm-2021-1247