Seroprevalence of IgG Antibodies Against SARS-CoV-2 N Protein Among Vaccinated and Unvaccinated Subjects in Lahore, Pakistan

The spread of SARS-CoV-2 represented a global health crisis. On May 5, 2023, the chief of the World Health Organization (WHO) officially announced the end of COVID-19 as a global health emergency. Serological assays can identify previously infected SARS-CoV-2 individuals, even if they did not go for testing while acutely ill. The current study sought to detect antibodies directed against the nucleocapsid of SARS-CoV-2 (IgG against the SARS-CoV-2 N protein) in both vaccinated and unvaccinated COVID-19 individuals. Of the 100 participants, 53 and 47 were vaccinated and unvaccinated, respectively. The vaccination status of the cohort based on gender data indicates that 41 (41%) of all participants were vaccinated males, whereas 12 (12%) were vaccinated females. We found that 42 (42%) were unvaccinated males and 5 (5%) were unvaccinated females. Of 53 vaccinated subjects, 42 and 11 participants were positive and negative for IgG against the SARS-CoV-2 N protein, respectively. Of 47 unvaccinated participants, 28 and 19 were positive and negative for IgG against the SARS-CoV-2 N protein, respectively. The average of S/P “Sample/Positive control” percentages, which correlate to levels of IgG against SARS-CoV-2 N protein, were significantly higher among the vaccinated patients (73.8%) as compared to non-vaccinated patients (57.1%), with p = 0.02. There was a downward trend in levels of IgG against the SARS-CoV-2 N protein with increasing age, except for the 60–69 age group.