AUTHOR=Weigert André , Bergman Marie-Louise , Gonçalves Lígia A. , Godinho Iolanda , Duarte Nádia , Abrantes Rita , Borges Patrícia , Brennand Ana , Malheiro Vanessa , Matoso Paula , Akpogheneta Onome , Kosack Lindsay , Cruz Pedro , Nogueira Estela , Pereira Magda , Ferreira Ana , Marques Marco , Nunes Telmo , Faro-Viana João , Demengeot Jocelyne , Penha-Gonçalves Carlos 

TITLE=Longitudinal Analysis of Antibody Responses to the mRNA BNT162b2 Vaccine in Patients Undergoing Maintenance Hemodialysis: A 6-Month Follow-Up

JOURNAL=Frontiers in Medicine

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2021.796676

DOI=10.3389/fmed.2021.796676

ISSN=2296-858X

ABSTRACT=<p><bold>Background:</bold> Patients on hemodialysis (HD) are at higher risk for COVID-19, overall are poor responders to vaccines, and were prioritized in the Portuguese vaccination campaign.</p><p><bold>Objective:</bold> This work aimed at evaluating in HD patients the immunogenicity of BTN162b2 after the two doses induction phase, the persistence of specific antibodies along time, and factors predicting these outcomes.</p><p><bold>Methods:</bold> We performed a prospective, 6-month long longitudinal cohort analysis of 156 HD patients scheduled to receive BTN162b2. ELISA quantified anti-spike IgG, IgM, and IgA levels in sera were collected every 3 weeks during the induction phase (t0 before vaccine; t1, d21 post first dose; and t2 d21 post second dose), and every 3–4 months during the waning phase (t3, d140, and t4, d180 post first dose). The age-matched control cohort was similarly analyzed from t0 to t2.</p><p><bold>Results:</bold> Upon exclusion of participants identified as previously exposed to SARS-CoV-2, seroconversion at t1 was lower in patients than controls (29 and 50%, respectively, <italic>p</italic> = 0.0014), while the second vaccine dose served as a boost in both cohorts (91 and 95% positivity, respectively, at t2, <italic>p</italic> = 0.2463). Lower response in patients than controls at t1 was a singularity of the participants ≤ 70 years (<italic>p</italic> = 2.01 × 10<sup>−05</sup>), associated with immunosuppressive therapies (<italic>p</italic> = 0.013), but not with lack of responsiveness to hepatitis B. Anti-spike IgG, IgM, and IgA levels decreased at t3, with IgG levels further waning at t4 and resulting in &gt;30% seronegativity. Anti-spike IgG levels at t1 and t4 were correlated (ρ = 0.65, <italic>p</italic> &lt; 2.2 × 10<sup>−16</sup>).</p><p><bold>Conclusions:</bold> While most HD patients seroconvert upon 2 doses of BNT162b2 vaccination, anti-spike antibodies levels wane over the following 4 months, leading to early seroreversion in a sizeable fraction of the patients. These findings warrant close monitoring of COVID-19 infection in vaccinated HD patients, and advocate for further studies following reinforced vaccination schedules.</p>