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Evaluation of antibody titer kinetics and SARS-CoV-2 infections in a large cohort of healthcare professionals ten months after administration of the BNT162b2 vaccine.
Ferrari, Davide; Ambrosi, Alessandro; Di Resta, Chiara; Tomaiuolo, Rossella; Locatelli, Massimo; Banfi, Giuseppe.
  • Ferrari D; SCVSA Department, University of Parma, 43121 Parma, Italy. Electronic address: davide.ferrari@unipr.it.
  • Ambrosi A; University Vita-Salute San Raffaele, 20158 Milan, Italy.
  • Di Resta C; IRCCS Ospedale San Raffaele, 20158 Milan, Italy.
  • Tomaiuolo R; University Vita-Salute San Raffaele, 20158 Milan, Italy.
  • Locatelli M; IRCCS Ospedale San Raffaele, 20158 Milan, Italy.
  • Banfi G; University Vita-Salute San Raffaele, 20158 Milan, Italy; IRCCS Orthopedic Institute Galeazzi, Laboratory of Clinical Chemistry and Microbiology, 20161 Milan, Italy.
J Immunol Methods ; 506: 113293, 2022 07.
Article in English | MEDLINE | ID: covidwho-2000542
ABSTRACT

BACKGROUND:

Real-world population studies have shown waning immunity, over time, after receiving the two doses of the BNT162b2 COVID-19 vaccine. Studies reporting the long-term humoral response are important to drive future vaccination strategies like the introduction of the booster dose. Yet, available literature on long follow-up periods is scarce. Covidiagnostix is a multicenter study aiming to assess the antibody response in >1000 healthcare professionals (HCPs) who received the BNT162b2 vaccine.

METHODS:

Serum was tested at time-0 (T0), before the first dose and then at T1, T2, T3 and T4, respectively, 21, 42, 177 and 302 days after T0. Antibodies against the SARS-CoV-2 nucleocapsid-protein were measured to assess SARS-CoV-2 infections, whereas antibodies against the receptor-binding domain of the spike protein were measured to assess vaccine response.

RESULTS:

The antibody titer observed 10 months post-vaccination showed a decrease of approximately 80% from the peak measured at T2, yet the median titer of the seronegatives HCPs was still higher than seropositives before vaccination. We identified 12 post-vaccination infected HCPs within 6 months after receiving the first dose and another 12 post-vaccination infected HCPs between 6 and 10 months post-vaccination.

CONCLUSION:

Vaccination induced a humoral response which is well detectable even 10 months post-vaccination. Yet a high anti-spike serum antibody titer does not guarantee protection from infection. Differences in symptomatology between SARS-CoV-2 infections occurred within the first 6 months post-vaccination and the following 4 months, and differences in COVID-19 prevalence and vaccination coverage observed in these two time intervals were consistent with a decrease in vaccine efficacy 6 months after receiving the first dose.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Viral Vaccines / COVID-19 Type of study: Cohort study / Experimental Studies / Observational study / Prognostic study Topics: Long Covid / Vaccines Limits: Humans Language: English Journal: J Immunol Methods Year: 2022 Document Type: Article

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Viral Vaccines / COVID-19 Type of study: Cohort study / Experimental Studies / Observational study / Prognostic study Topics: Long Covid / Vaccines Limits: Humans Language: English Journal: J Immunol Methods Year: 2022 Document Type: Article