AUTHOR=Serwanga Jennifer , Baine Claire , Mugaba Susan , Ankunda Violet , Auma Betty Oliver , Oluka Gerald Kevin , Kato Laban , Kitabye Isaac , Sembera Jackson , Odoch Geoffrey , Ejou Peter , Nalumansi Amina , Gombe Ben , Musenero Monica , Kaleebu Pontiano , the COVID-19 Immunoprofiling Team , Akoli Christine Hermilia , Mwesigwa Deus , Ssali Ivan , Nantambi Hellen , Namuyanja Angela , Opio Solomon , Kalyebi Arthur Watelo , Katende Joseph Ssebwana TITLE=Seroprevalence and durability of antibody responses to AstraZeneca vaccination in Ugandans with prior mild or asymptomatic COVID-19: implications for vaccine policy JOURNAL=Frontiers in Immunology VOLUME=14 YEAR=2023 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2023.1183983 DOI=10.3389/fimmu.2023.1183983 ISSN=1664-3224 ABSTRACT=Introduction

The duration and timing of immunity conferred by COVID-19 vaccination in sub-Saharan Africa are crucial for guiding pandemic policy interventions, but systematic data for this region is scarce. This study investigated the antibody response after AstraZeneca vaccination in COVID-19 convalescent Ugandans.

Methods

We recruited 86 participants with a previous rt-PCR-confirmed mild or asymptomatic COVID-19 infection and measured the prevalence and levels of spike-directed IgG, IgM, and IgA antibodies at baseline, 14 and 28 days after the first dose (priming), 14 days after the second dose (boosting), and at six- and nine-months post-priming. We also measured the prevalence and levels of nucleoprotein-directed antibodies to assess breakthrough infections.

Results

Within two weeks of priming, vaccination substantially increased the prevalence and concentrations of spike-directed antibodies (p < 0.0001, Wilcoxon signed rank test), with 97.0% and 66% of vaccinated individuals possessing S-IgG and S-IgA antibodies before administering the booster dose. S-IgM prevalence changed marginally after the initial vaccination and barely after the booster, consistent with an already primed immune system. However, we also observed a rise in nucleoprotein seroprevalence, indicative of breakthroughs six months after the initial vaccination.

Discussion

Our results suggest that vaccination of COVID-19 convalescent individuals with the AstraZeneca vaccine induces a robust and differential spike-directed antibody response. The data highlights the value of vaccination as an effective method for inducing immunity in previously infected individuals and the importance of administering two doses to maintain protective immunity. Monitoring anti-spike IgG and IgA when assessing vaccine-induced antibody responses is suggested for this population; assessing S-IgM will underestimate the response. The AstraZeneca vaccine is a valuable tool in the fight against COVID-19. Further research is needed to determine the durability of vaccine-induced immunity and the potential need for booster doses.