Maki FM, Al-Thwani AN, Jiad KS, Musafer KNJ. Immunoglobulin G follow-up and immune response longevity analysis in SARS-CoV-2 convalescent patients and vaccinated individuals: A longitudinal analysis.
Hum Antibodies 2023:HAB230004. [PMID:
37334588 DOI:
10.3233/hab-230004]
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Abstract
BACKGROUND
Although the detection of immunoglobulin G (IgG) molecules has long been considered to be crucial for successful humoral immune defence against infections and harmful metabolites, it has become increasingly important in relation to SARS-CoV-2 research.
OBJECTIVE
To compare longitudinal changes in IgG titres in post-infection and post-vaccination Iraqi participants, and to estimate the protective benefits of the two principal vaccines used in Iraq.
METHODS
This quantitative study used samples from SARS-CoV-2 recovered patients (n= 75), those vaccinated with two doses of Pfizer or Sinopharm vaccine (n= 75), and healthy unvaccinated individuals (n= 50) who formed a control group. Participant ages (range 20-80 years) and sex (52.7% men, 47.3% females). An enzyme-linked immunosorbent assay was used to measure IgG.
RESULTS
IgG antibody levels peaked in the first month and tapered off in the following three months in both convalescent and vaccinated groups. The latter showed a significant decrease in IgG titres than in the convalescent group. Samples from the group given the mRNA vaccination that targeted spike (S) proteins might have a cross-reactivity between nucleocapsid (N) and spike (S) proteins.
CONCLUSIONS
Participants who had recovered from or who were vaccinated against SARS-CoV-2 exhibited a protective, persistent and durable humoral immune response for at least a month. This was more potent in the SARS-CoV-2 convalescent group compared to the vaccinated cohort. The IgG titres decayed faster after vaccination with Sinopharm than following the Pfizer-BioNTech vaccine.
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