A Single Dose of COVID-19 mRNA Vaccine Induces Airway Immunity in COVID-19 Convalescent Patients (preprint)

BackgroundMucosal antibodies can prevent virus entry and replication in mucosal epithelial cells and hence virus shedding. Preclinical and clinical studies have shown that a parenteral booster injection of a vaccine against a mucosal pathogen promotes stronger mucosal immune responses following prior infection compared to two injections of a parenteral vaccine. We investigated whether this was also the case for a COVID-19 mRNA vaccine. MethodsTwenty-three COVID-19 convalescent patients and 20 SARS-CoV-2-naive subjects were vaccinated with respectively one and two doses of the Pfizer-BioNTech COVID-19 RNA vaccine. Nasal Epithelial Lining Fluid (NELF) and plasma were collected before and after vaccination and assessed for Immunoglobulin (Ig)G and IgA to Spike and for their ability to inhibit the binding of Spike to its ACE-2 receptor. Blood was analyzed one week after vaccination for the number of Spike-specific Antibody Secreting Cells (ASCs) with a mucosal tropism. ResultsIn COVID-19 convalescent patients, a single dose of vaccine amplified pre-existing Spike-specific IgG and IgA antibody responses in both NELF and blood against both vaccine homologous and variant strains, including delta. These responses were associated with Spike-specific IgG and IgA ASCs with a mucosal tropism in blood. Nasal IgA and IgG antibody responses were lower in magnitude in SARS-CoV-2-naive subjects after two vaccine doses ConclusionThis study showed that a parenteral booster injection of a COVID-19 RNA vaccine promoted stronger mucosal immune responses in COVID-19 convalescent patients compared to SARS-CoV-2 naive subjects who had received a first vaccine dose.

Changing of therapeutic trends between the 1st and 2nd wave did not reduce COVID-19 related mortality of renal transplant recipients: a national registry study. (preprint)

SARS-CoV-2 pandemic evolved in two consecutive waves over 2020 (for France: 1st wave from March 1 to July 31; and 2nd wave from August 1 to December 31). Improvements in the management of COVID-19 led to a reduction of mortality rates in hospitalized patients during the second wave. Whether this progress also benefited to kidney transplant recipients (KTR), a population particularly vulnerable to severe COVID-19, remained unclear. In France, 957 KTR were hospitalized for COVID-19 in 2020 and their data were prospectively collected in the French SOT COVID registry. The presentation, management, and outcomes of the 359 KTR diagnosed during the 1st wave were compared to those of the 598 of the 2nd wave. Baseline comorbidities were largely similar between KTR of the 2 waves. Maintenance immunosuppression was reduced in most patients but withdrawal of antimetabolite (73.7% vs 58.4%, p<0.001) or CNI (32.1% vs 16.6%, p<0.001) was less frequent during the 2nd wave. Hydroxychloroquine and azithromycin that were commonly used during the 1st wave (21.7% and 30.9%, respectively) were almost abandoned during the 2nd. In contrast, the use of high dose corticosteroids doubled (19.5% vs. 41.6%, p<0.001). Despite these changing trends in COVID-19 management, 60-day mortality was not statistically different between the 2 waves (25.3% vs. 23.9%; Log Rank, p=0.48). We conclude that changing of therapeutic trends during 2020 did not reduce COVID-19 related mortality in KTR. Our data indirectly support the importance of vaccination and monoclonal neutralizing anti-SARS-CoV-2 antibodies to protect KTR from severe COVID-19.

Safety and Cross-Variant Immunogenicity of a Three-Dose COVID-19 mRNA Vaccine Regimen in Kidney Transplant Recipients (preprint)

Background: The immunogenicity of a two-dose mRNA COVID-19 vaccine regimen is low in kidney transplant (KT) recipients. We report the first complete assessment of safety and cross-variant immunogenicity of a three-dose vaccine regimen in KT recipients.Methods: We performed a prospective longitudinal study in sixty-one KT recipients given three doses of the BNT162b2 COVID-19 vaccine. We performed semi-structured pharmacovigilance interviews and monitored donor-specific antibodies and kidney function. We compared geometric mean titers (GMT) of anti-spike IgG, pseudo-neutralization activity against vaccine homologous and heterologous variants, frequency of spike-specific interferon (IFN)-γ-secreting cells, and antigen-induced cytokine production 28 days after the second and third doses. The immunoassays were also performed in non-transplanted individuals 28 days after the second dose to obtain reference values.Findings: Reactions to vaccine were mild. One patient developed donor-specific anti-HLA antibodies after the second dose which could be explained by non-adherence to immunosuppressive therapy. Spike-specific IgG seroconversion raised from 44·3% (n=27) after the second dose to 62·3% (n=38) after the third dose (p<0·05). GMT increased from 528·3 (95% CI 300·0-930·1) to 2395 AU/ml (95% CI 1214-4724, p<0·0001). Serum neutralizing activity increased from 4·7% to 17·2% (Wuhan strain), 4·0% to 17·4% (alpha variant), 2·3% to 7·3% (beta variant), and 1·3% to 9·1% (gamma variant) after the third dose (p<0·0001), which remained lower than reference values. The mean frequency of IFN-γ-secreting cells increased from 19·9 (SD 56·0) to 64·0 (SD 76·8) cells/million PBMCs after the third dose (p<0·0001). A significant increase in IFN-γ responses was also observed in patients who remained seronegative after three doses (p<0·0001).Interpretation: A third dose of the BNT162b2 vaccine increases both SARS-CoV-2-specific humoral and cellular responses in KT recipients with an acceptable tolerability profile. However, neutralizing antibody titres remain low after three doses, especially against variants of concern, and barrier measures and vaccination of the relatives remain essential.Funding Information: This work was supported by grants from the Nice University Hospital (AOI) and the University of Cote d’Azur (IDEX).Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: The study protocol complies with the principles of the Declaration of Helsinki and was approved by our institutional committee. Written informed consent was obtained from all participants and all collected data and samples were anonymized and securely stored.