CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

393

Prior COVID-19 Alters Antibody Function in ART-Suppressed PWH Receiving SARS- CoV-2 Vaccination Livio Azzoni 1 , Ian Tietjen 1 , Qin Liu 1 , Shalini Singh 1 , Mansi Purwar 1 , Matthew Fair 1 , Paridhima Sharma 1 , Leila B. Giron 1 , Jianyi Ding 1 , Linden Lalley-Chareczko 2 , Emily Hiserodt 2 , Karam Mounzer 2 , David B. Weiner 1 , Mohamed Abdel-Mohsen 1 , Luis J. Montaner 1 1 Wistar Institute, Philadelphia, PA, USA, 2 Philadelphia FIGHT, Philadelphia, PA, USA Background: People with HIV infection (PWH) receiving suppressive antiretroviral therapy (ART) develop vaccine-driven immune responses (anti RBD antibodies, RBD/ACE binding competition and neutralization) to early SARS-CoV-2 isolates similar to the general population. However, the impact of previous SARS-CoV-2 infection on the humoral and cellular immune response after a two-dose SARS-CoV-2 RNA vaccination in PWH on ART is unknown. Methods: We collected peripheral blood from 44 PWH on ART (n=24 with prior SARS-CoV-2 infection; HIV POS /COVID POS and n=20 who did not report prior SARS-CoV-2 infection; 24: HIV POS /COVID NEG ) at four time points: 1) before the 1st and 2nd dose of RNA-based vaccine, and 3 and 6 months after 2nd dose. We assessed total spike (S), RBD, and nucleocapsid (N) titers and neutralizing antibody titers (ELISA; Spike/ACE2 HTRF against Wuhan, β, δ, λ, and ο variants; pseudo-neutralization of ο BA.1 and BA.2 ), Fc-mediated antibody-dependent cytotoxicity (ADCC), complement deposition (ADCD), and cellular phagocytosis (ADCP), SARS-Cov-2 and HIV-specific T cell responses (IFN-γ ELISPOT), and T cell and monocyte activation (Flow cytometry). Changes from baseline and between visits were assessed using the Wilcoxon signed rank test. Results: Neutralizing antibody titers against spike protein (all variants) were elicited by vaccination in both groups, but were significantly higher and better retained in the HIV POS /COVID POS group, including antibody titers against ο BA.1 and BA.2 pseudotypes, compared to HIV POS /COVID NEG group. Non-neutralizing antibody responses (ADCC and ADCP) were induced in both group; however, ADCD was significantly enhanced in the HIV POS /COVID POS group than the HIV POS / COVID NEG group. Both groups showed persistent increase in T-cell and monocyte activation following vaccination, yet without a parallel increase in T-cell- specific responses to HIV Gag or Nef. Conclusion: Prior SARS-CoV-2 infection is associated with greater non neutralizing antibody innate immune effector functions and a broader anti-SARS-CoV-2 immune response (including greater activity against Omicron variants) in PWH on ART following Wuhan strain RNA vaccination. Further studies are needed to examine the impact of vaccination-induced, Fc-mediated innate immune functions on re-infection and/or disease course. Distinct Absence of Post-Boost S-IgG Surge in Sub-Saharan African COVID-19 Vaccine Responses Jennifer Serwanga , Violet Ankunda, Joseph S. Katende, Jackson Sembera, Gerald K. Oluka, Claire Baine, Pontiano Kaleebu Uganda Virus Research Institute, Entebbe, Uganda Background: This study investigated the longitudinal antibody response profiles and their durability after administering various COVID-19 vaccines to a subset of the Ugandan population within Sub-Saharan Africa (SSA). The hypothesis was that these profiles in SSA may exhibit unique characteristics due to genetic, environmental, or serological variations, thereby addressing significant gaps in global datasets and contributing insights specific to response patterns within this demographic. Methods: Participants were enrolled to assess the temporal evolution and persistence of antibody responses for 12 months post-initial vaccination. These included 48 individuals vaccinated with Pfizer, 67 with AstraZeneca, and 21 with Moderna, all receiving two doses 28-30 days apart. Additionally, 60 participants who received the Sinovac vaccine were included, with their doses administered three months apart. A validated enzyme-linked immunosorbent assay (ELISA) was used to measure concentrations and optical densities (ODs) of SARS-CoV- 2-specific IgG, IgM, and IgA binding antibodies. The OD threshold values for determining antibody positivity in this population were S-directed IgG at 0.432, IgM at 0.459, and IgA at 0.226. Statistical analyses included box plots, diverging bar graphs, and the Wilcoxon test with a Bonferroni correction for multiple analysis. Results: All four vaccines demonstrated a significant increase in Spike-directed IgG antibody concentrations within 14 days of the initial vaccine dose declining by six months, mirroring global observations. A significant observation was the lack of the anticipated surge in S-IgG levels following the booster dose. This trend starkly contrasted findings noted in various other global populations.

The S-IgM response was transient and mostly subsided below the established thresholds, illustrating its initial early emergence and subsequent decline. S-IgA highlighted the temporal dynamics of mucosal immunity, showing an initial increase and then a reduction by six months post-vaccination. Breakthrough infections occurred at similar levels across all vaccines studied; however, they were all asymptomatic. Conclusion: These data emphasise the critical need for inclusion of region specific research to formulate vaccination strategies attuned to regions like SSA's unique environmental, genetic, and serological landscapes, ensuring the development of relevant vaccination policies.

395

Disparities in Anti-SARS-CoV-2 Reactivity According to Vaccines in the Era of Omicron in Cameroon Ezechiel Ngoufack Jagni Semengue 1 , Joseph Fokam 1 , Desire Takou 1 , Collins Ambe Chenwi 1 , Grace Beloumou 1 , Alex Durand NKA 1 , Aurelie Minelle Ngueko Kengni 1 , Sandrine Djupsa 1 , Alexis Ndjolo 1 , Carlo Federico Perno 2 , Vittorio Colizzi 1 1 Centre International de Référence Chantal Biya, Yaoundé, Cameroon, 2 Bambino Gesu Children's Hospital, Rome, Italy Background: Anti-SARS-CoV-2 vaccine remains a global health priority, but evidence on its significance within tropical settings like Cameroon is limited. Our objective was to assess the overall rate of COVID-19 antibodies, its disparity according to vaccine-status and types of vaccines administered in Cameroon during the active phase of Omicron variants. Methods: A cross-sectional sero-survey was conducted from february throughout July-2022 (active phase of Omicron circulation) among individuals tested for COVID-19 in Yaoundé-Cameroon. Socio-demographic and detailed clinical data were collected; SARS-CoV-2 antibodies were tested on plasma using Ninonasal TM and ABBEXA TM COVID-19 IgG/IgM assays. Statistical analyses were performed with p<0.05 statistically significant. Results: A total of 2449 participants were enrolled: median [IQR] age was 40 [31–48], 56.4%(1382/2449) men, 2.2%(54/2449) with flu-like symptoms and 19.6%(481/2449) reporting previous SARS-CoV-2 positivity (confirmed with PCR). Regarding COVID-19 vaccination, 67.5%(1652/2449) had received at least one dose (48.7% Pfizer, 24.8% Johnson&Johnson, 18.2% Moderna; 8.1% AstraZeneca, 4.8% Sinopharm and 0.2% Sputnik-light) ; among these, 55.0%(909/1652) were fully vaccinated and 37.1%(613/1652) received additional boost doses. Median duration from vaccination to phlebotomy was 5 [3–8] months (min: 1; max: 20). Overall, rate of COVID-19 antibodies was 81.13%(1987/2449), with 1.2% IgM, 73.9% IgG and 6.5% IgM/IgG. Following univariate analysis, high prevalence of antibodies was associated to vaccination (OR=1.9; p<0.0001). Among the vaccinated, those who received boost doses had higher odds for COVID-19 antibodies (OR=2.5; p<0.0001) and regarding the vaccines, Pfizer induced the greater immunogenicity (OR=2.4; p<0.0001); and post vaccination time ≤5months (OR=2.3; p=0.001) was also a determinant of high COVID-19 antibodies. Following multivariate analysis, the vaccine-status, Pfizer vaccine, booster doses and post vaccination time remained statistically associated with the high prevalence of COVID-19 antibodies (aOR=3.1, OR=2.5, aOR=2.1, and aOR=3.04 respectively; with all p<0.001). Conclusion: The high-rate of COVID-19 antibodies suggests herd immunity at community-level in Cameroon, during the wide circulation of Omicron. Furthermore, vaccination with Pfizer appears with higher Covid-19 antibody response, supporting the need for vaccine update with novel variants, especially with the rapid antibody weaning (~5months) in this tropical setting.

Poster Abstracts

394

94

CROI 2024