Antibody Titer Kinetics and SARS-CoV-2 Infections Six Months after Administration with the BNT162b2 Vaccine.

Abstract

BACKGROUND:

Studies reporting the long-term humoral response after receiving the BNT162b2 COVID-19 vaccine are important to drive future vaccination strategies. Yet, available literature is scarce. Covidiagnostix is a multicenter study designed 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, T1, T2, and T3, respectively, 21, 42, and 180 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 the vaccine response. Neutralization activity against the D614G, B.1.1.7, and B.1.351 variants were also analyzed.

RESULTS:

Six months post-vaccination HCPs showed an antibody titer decrease of approximately 70%, yet, the titer was still one order of magnitude higher than that of seropositive individuals before vaccination. We identified 12 post-vaccination infected HCPs. None showed severe symptoms. Interestingly, most of them showed titers at T2 above the neutralization thresholds obtained from the neutralization activity experiments.

CONCLUSION:

Vaccination induces a humoral response which is well detectable even six months post-vaccination. Vaccination prevents severe COVID-19 cases, yet post-vaccination infection is possible even in the presence of a high anti-S serum antibody titer.

• Authors: Davide Ferrari, Nicola Clementi, Elena Criscuolo, Alessandro Ambrosi, Francesca Corea, Chiara Di Resta, Rossella Tomaiuolo, Nicasio Mancini, Massimo Locatelli, Mario Plebani, Giuseppe Banfi
• Journal: Vaccines (Vaccines (Basel)) Vol. 9 Issue 11 (Nov 19 2021) ISSN: 2076-393X [Print] Switzerland
• PMID: 34835288 (Publication Type: Journal Article)