Anti- SARS-CoV-2 IgG and IgM Levels in Iraqi General Population.

Background: Acquired immunity plays an important role in the prevention of viral infections. SARS-CoV-2 is an infection that leads to a pandemic. The development of specific anti-SARSCoV- 2 antibodies may play a vital role in disease prevention and control. Thus IgG antibody screening in the general population provides information on the immunological status of the community.

Aim: To clarify the SARS-CoV-2 immune status in the general population.

Methods: A cross-sectional study was conducted in Kirkuk province during the period from 15 May 2022 to 11 September 2022. The samples were collected from voluntary subjects and informed consent was taken from each participant before their enrolment in the study. SARS-CoV-2 IgG, SARSCoV- 2 IgM, 25-OH Vitamin D, Vitamin B12, and Folate were determined using the Electrochemiluminescence Immunoassay (eCLIA) technique with the instrument NIPIGON-Robot R1Automated ECL Analyzer (Canada).

Results: The overall IgG mean concentration was 37.75 ± 23.18 COI, with a median of 39.99 COI and a range of 0.25 - 87.23 COI. Additionally, 93% of tested samples were with concentrations of more than 1 COI. The highest frequency (18.2%) was for the IgG concentration of 51 to 60 COI, while the lowest frequency (1.3%) was for the concentration of 81 - 90 COI. The IgG was significantly higher (P = 0.046) in males (39.87 ± 24.04 COI) than that in females (35.12 ± 21.89 COI). The IgM overall concentration was 0.569 ± 0.456 COI, with a median of 0.489 COI and a range of 0.17 - 6.40 COI. The mean serum level of folic acid concentration was 9.03 ± 5.72 ng/ml, with a median of 7.476 ng/ml and a range of 0.60 - 20.00 ng/ml. The mean serum concentration of vitamin B12 was 462.65 ± 349.18 pg/ml, with a median of 353 pg/ml and a range of 13.05 - 2000 pg/ml. The mean serum concentration of vitamin D was 18.29 ± 18.42 ng/ml with a median of 12.44 ng/ml and a range of 3 - 100 ng/ml. IgG and IgM serum levels did not show a significant correlation with serum levels of folic acid, vitamin D, and vitamin B12. However, there was a significant correlation between folic acid and vitamin D (r = 0.197; P = 0.012); vitamin B12 and vitamin D (r = 0.253, P = 0.001). While there was a non-significant correlation between folic acid and vitamin D serum levels (r = 0.129, P = 0.10).

Conclusion: General population IgG antibody concentration reflects a high rate of herd immunity. Folic acid was with a mean value of about half of the upper normal limit and only 17.7% were with low values. Vitamin B12, only 6.3% of the population had values lower than normal. However, the range of vitamin B12 was wide. While vitamin D values were lower than the normal limit at 82.6%. However, a large scale well designed was warranted to evaluate COVID-19 national immune response.