Humoral Immune Responses following COVID-19 Vaccinations among Adults in Tanzania.

Humoral Immune Responses following COVID-19 Vaccinations among Adults in Tanzania.

Publication date: Dec 23, 2023

COVID-19 vaccination remains to be the most important intervention in the fight against the pandemic. The immunity among the vaccinated population and its durability can significantly vary due to various factors. This study investigated the humoral immune responses among individuals who received any of the COVID-19 vaccines approved for use in Tanzania. A total of 1048 randomly selected adults who received COVID-19 vaccines at different time points were enrolled and humoral immune responses (IR) were tested at baseline and three months later (960, 91. 6%). The level of SARS-CoV-2 anti-spike/receptor binding domain (RBD) IgG, anti-nucleocapsid IgG, and IgM antibodies were determined using a commercially available chemiluminescent microparticle immunoassay. Descriptive data analysis was performed using STATA version 18 and R. At baseline, serum IgG against anti-spike/RBD was detected in 1010/1048 (96. 4%) participants (95%CI: 94. 9-97. 5) and 98. 3% (95%CI: 97. 3-99) three months later. The IgG against the SARS-CoV-2 nucleocapsid proteins were detected in 40. 8% and 45. 3% of participants at baseline and follow-up, respectively. The proportion of seroconverters following vaccination and mean titers of anti-spike/RBD antibodies were significantly more among those who had past SARS-CoV-2 infection than in those with no evidence of past infection, (p < 0. 001). Only 0. 5% of those who had detectable anti-spike/RBD antibodies at baseline were negative after three months of follow-up and 1. 5% had breakthrough infections. The majority of participants (99. 5%) had detectable anti-spike/RBD antibodies beyond 6 months post-vaccination. The proportion of Tanzanians who mounted humoral IR following COVID-19 vaccination was very high. Seroconversions, as well as the mean titers and durability of humoral IR, were significantly enhanced by exposure to natural SARS-CoV-2 infection. In view of the limited availability of COVID-19 vaccines as well as challenges to completing subsequent doses, booster doses could only be suggested to high-risk groups.

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Concepts Keywords
Basel adults
Pandemic COVID-19 vaccines
Tanzania humoral immune response
Vaccinated Tanzania


Type Source Name
disease MESH COVID-19
disease VO vaccination
disease IDO intervention
disease VO vaccinated
disease VO population
disease VO time
pathway REACTOME SARS-CoV-2 Infection
disease MESH infection
disease MESH breakthrough infections
disease MESH Seroconversions
drug DRUGBANK Coenzyme M
drug DRUGBANK Ranitidine
disease IDO humoral immune response
disease MESH emergency
disease VO organization
disease IDO country
disease VO effective
disease VO vaccine
disease MESH hypertension
disease MESH diabetes mellitus
disease MESH obesity
disease VO dose
disease VO Ad26.COV2.S
disease VO USA
disease IDO blood
disease IDO history
disease MESH comorbidity
disease IDO algorithm
disease IDO assay
drug DRUGBANK Immune Globulin Human
disease MESH Education level
disease IDO acute infection
disease VO immunization

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